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<br>STM32F4 LoRa UART Driver
PRE-RELEASE
An STM32F4, RYLR998 LoRa UART driver written entirely in Assembler.
<br>Code
/**
* FILE: main.s
*
* DESCRIPTION:
* This file contains the assembly code for a STM32F401 LoRa UART driver utilizing the STM32F401CC6
* microcontroller.
*
* AUTHOR: Kevin Thomas
* CREATION DATE: March 15, 2024
* UPDATE DATE: March 31, 2024
*
* ASSEMBLE AND LINK w/ SYMBOLS:
* 1. arm-none-eabi-as -g main.s -o main.o
* 2. arm-none-eabi-ld main.o -o main.elf -T STM32F401CCUX_FLASH.ld
* 3. openocd -f interface/stlink.cfg -f target/stm32f4x.cfg -c "program main.elf verify reset exit"
* ASSEMBLE AND LINK w/o SYMBOLS:
* 1. arm-none-eabi-as -g main.s -o main.o
* 2. arm-none-eabi-ld main.o -o main.elf -T STM32F401CCUX_FLASH.ld
* 3. arm-none-eabi-objcopy -O binary --strip-all main.elf main.bin
* 3. openocd -f interface/stlink.cfg -f target/stm32f4x.cfg -c "program main.bin 0x08000000 verify reset exit"
* DEBUG w/ SYMBOLS:
* 1. openocd -f interface/stlink.cfg -f target/stm32f4x.cfg
* 2. arm-none-eabi-gdb main.elf
* 3. target remote :3333
* 4. monitor reset halt
* 5. l
* DEBUG w/o SYMBOLS:
* 1. openocd -f interface/stlink.cfg -f target/stm32f4x.cfg
* 2. arm-none-eabi-gdb main.bin
* 3. target remote :3333
* 4. monitor reset halt
* 5. x/8i $pc
*/
.syntax unified
.cpu cortex-m4
.fpu softvfp
.thumb
/**
* The start address for the .data section defined in linker script.
*/
.word _sdata
/**
* The end address for the .data section defined in linker script.
*/
.word _edata
/**
* The start address for the initialization values of the .data section defined in linker script.
*/
.word _sidata
/**
* The start address for the .bss section defined in linker script.
*/
.word _sbss
/**
* The end address for the .bss section defined in linker script.
*/
.word _ebss
/**
* Provide weak aliases for each Exception handler to the Default_Handler. As they are weak aliases, any function
* with the same name will override this definition.
*/
.macro weak name
.global \name
.weak \name
.thumb_set \name, Default_Handler
.word \name
.endm
/**
* Initialize the .isr_vector section. The .isr_vector section contains vector table.
*/
.section .isr_vector, "a"
/**
* The STM32F401CCUx vector table. Note that the proper constructs must be placed on this to ensure that it ends up
* at physical address 0x00000000.
*/
.global isr_vector
.type isr_vector, %object
isr_vector:
.word _estack
.word Reset_Handler
weak NMI_Handler
weak HardFault_Handler
weak MemManage_Handler
weak BusFault_Handler
weak UsageFault_Handler
.word 0
.word 0
.word 0
.word 0
weak SVC_Handler
weak DebugMon_Handler
.word 0
weak PendSV_Handler
weak SysTick_Handler
.word 0
weak EXTI16_PVD_IRQHandler // EXTI Line 16 interrupt PVD through EXTI line detection
weak TAMP_STAMP_IRQHandler // Tamper and TimeStamp interrupts through the EXTI line
weak EXTI22_RTC_WKUP_IRQHandler // EXTI Line 22 interrupt RTC Wakeup interrupt, EXTI line
weak FLASH_IRQHandler // FLASH global interrupt
weak RCC_IRQHandler // RCC global interrupt
weak EXTI0_IRQHandler // EXTI Line0 interrupt
weak EXTI1_IRQHandler // EXTI Line1 interrupt
weak EXTI2_IRQHandler // EXTI Line2 interrupt
weak EXTI3_IRQHandler // EXTI Line3 interrupt
weak EXTI4_IRQHandler // EXTI Line4 interrupt
weak DMA1_Stream0_IRQHandler // DMA1 Stream0 global interrupt
weak DMA1_Stream1_IRQHandler // DMA1 Stream1 global interrupt
weak DMA1_Stream2_IRQHandler // DMA1 Stream2 global interrupt
weak DMA1_Stream3_IRQHandler // DMA1 Stream3 global interrupt
weak DMA1_Stream4_IRQHandler // DMA1 Stream4 global interrupt
weak DMA1_Stream5_IRQHandler // DMA1 Stream5 global interrupt
weak DMA1_Stream6_IRQHandler // DMA1 Stream6 global interrupt
weak ADC_IRQHandler // ADC1 global interrupt
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
weak EXTI9_5_IRQHandler // EXTI Line[9:5] interrupts
weak TIM1_BRK_TIM9_IRQHandle // TIM1 Break interrupt and TIM9 global interrupt
weak TIM1_UP_TIM10_IRQHandler // TIM1 Update interrupt and TIM10 global interrupt
weak TIM1_TRG_COM_TIM11_IRQHandler // TIM1 T/C interrupts, TIM11 global interrupt
weak TIM1_CC_IRQHandler // TIM1 Capture Compare interrupt
weak TIM2_IRQHandler // TIM2 global interrupt
weak TIM3_IRQHandler // TIM3 global interrupt
weak TIM4_IRQHandler // TIM4 global interrupt
weak I2C1_EV_IRQHandler // I2C1 event interrupt
weak I2C1_ER_IRQHandler // I2C1 error interrupt
weak I2C2_EV_IRQHandler // I2C2 event interrupt
weak I2C2_ER_IRQHandler // I2C2 error interrupt
weak SPI1_IRQHandler // SPI1 global interrupt
weak SPI2_IRQHandler // SPI2 global interrupt
weak USART1_IRQHandler // USART1 global interrupt
weak USART2_IRQHandler // USART2 global interrupt
.word 0 // reserved
weak EXTI15_10_IRQHandler // EXTI Line[15:10] interrupts
weak EXTI17_RTC_Alarm_IRQHandler // EXTI Line 17 interrupt / RTC Alarms (A and B) EXTI
weak EXTI18_OTG_FS_WKUP_IRQHandler // EXTI Line 18 interrupt / USBUSB OTG FS Wakeup EXTI
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
weak DMA1_Stream7_IRQHandler // DMA1 Stream7 global interrupt
.word 0 // reserved
weak SDIO_IRQHandler // SDIO global interrupt
weak TIM5_IRQHandler // TIM5 global interrupt
weak SPI3_IRQHandler // SPI3 global interrupt
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
weak DMA2_Stream0_IRQHandler // DMA2 Stream0 global interrupt
weak DMA2_Stream1_IRQHandler // DMA2 Stream1 global interrupt
weak DMA2_Stream2_IRQHandler // DMA2 Stream2 global interrupt
weak DMA2_Stream3_IRQHandler // DMA2 Stream3 global interrupt
weak DMA2_Stream4_IRQHandler // DMA2 Stream4 global interrupt
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
weak OTG_FS_IRQHandler // USB On The Go FS global interrupt
weak DMA2_Stream5_IRQHandler // DMA2 Stream5 global interrupt
weak DMA2_Stream6_IRQHandler // DMA2 Stream6 global interrupt
weak DMA2_Stream7_IRQHandler // DMA2 Stream7 global interrupt
weak USART6_IRQHandler // USART6 global interrupt
weak I2C3_EV_IRQHandler // I2C3 event interrupt
weak I2C3_ER_IRQHandler // I2C3 error interrupt
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
.word 0 // reserved
weak SPI4_IRQHandler // SPI4 global interrupt
/**
* @brief This code is called when processor starts execution.
*
* This is the code that gets called when the processor first starts execution following a reset event. We
* first define and init the bss section and then define and init the data section, after which the
* application supplied main routine is called.
*
* @param None
* @retval None
*/
.type Reset_Handler, %function
.global Reset_Handler
Reset_Handler:
LDR R4, =_estack // load address at end of the stack into R0
MOV SP, R4 // move address at end of stack into SP
LDR R4, =_sdata // copy the data segment initializers from flash to SRAM
LDR R5, =_edata // copy the data segment initializers from flash to SRAM
LDR R6, =_sidata // copy the data segment initializers from flash to SRAM
MOVS R7, #0 // copy the data segment initializers from flash to SRAM
B .Reset_Handler_Loop_Copy_Data_Init // branch
.Reset_Handler_Copy_Data_Init:
LDR R8, [R6, R7] // copy the data segment initializers into registers
STR R8, [R4, R7] // copy the data segment initializers into registers
ADDS R7, R7, #4 // copy the data segment initializers into registers
.Reset_Handler_Loop_Copy_Data_Init:
ADDS R8, R4, R7 // initialize the data segment
CMP R8, R5 // initialize the data segment
BCC .Reset_Handler_Copy_Data_Init // branch if carry is clear
LDR R6, =_sbss // copy the bss segment initializers from flash to SRAM
LDR R8, =_ebss // copy the bss segment initializers from flash to SRAM
MOVS R7, #0 // copy the bss segment initializers from flash to SRAM
B .Reset_Handler_Loop_Fill_Zero_BSS // branch
.Reset_Handler_Fill_Zero_BSS:
STR R7, [R6] // zero fill the bss segment
ADDS R6, R6, #4 // zero fill the bss segment
.Reset_Handler_Loop_Fill_Zero_BSS:
CMP R6, R8 // zero fill the bss segment
BCC .Reset_Handler_Fill_Zero_BSS // branch if carry is clear
BL main // call function
/**
* @brief This code is called when the processor receives and unexpected interrupt.
*
* This is the code that gets called when the processor receives an unexpected interrupt. This simply enters
* an infinite loop, preserving the system state for examination by a debugger.
*
* @param None
* @retval None
*/
.type Default_Handler, %function
.global Default_Handler
Default_Handler:
BKPT // set processor into debug state
B.N Default_Handler // call function, force thumb state
/**
* Initialize the .text section. The .text section contains executable code.
*/
.section .text
/**
* @brief Entry point for initialization and setup of specific functions and main routine.
*
* This function is the entry point for initializing and setting up specific functions. It calls other
* functions to enable certain features and then enters a loop for further execution.
*
* @param None
* @retval None
*/
.type main, %function
.global main
main:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
BL GPIOA_Enable // call function
BL GPIOB_Enable // call function
BL GPIOC_Enable // call function
BL I2C1_Enable // call function
BL GPIOA_PA2_Alt_Function_Mode_Enable // call function
BL GPIOA_PA3_Alt_Function_Mode_Enable // call function
BL GPIOB_PB8_Alt_Function_Mode_Enable // call function
BL GPIOB_PB8_Open_Drain_Enable // call function
BL GPIOB_PB9_Alt_Function_Mode_Enable // call function
BL GPIOB_PB9_Open_Drain_Enable // call function
BL GPIOB_PB0_Input_Enable // call function
BL GPIOB_PB1_Input_Enable // call function
BL GPIOB_PB2_Input_Enable // call function
BL GPIOB_PB3_Input_Enable // call function
BL GPIOB_PB4_Input_Enable // call function
BL GPIOB_PB5_Input_Enable // call function
BL I2C1_Init // call function
BL SSD1306_Init // call function
BL SSD1306_Turn_On_Display // call function
BL USART2_Enable // call function
BL USART2_Transmit_Enable // call function
BL USART2_Receive_Enable // call function
//BL LoRa_Setup // call function
BL Loop // call function
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables the GPIOA peripheral by setting the corresponding RCC_AHB1ENR bit.
*
* @details This function enables the GPIOA peripheral by setting the corresponding RCC_AHB1ENR bit. It loads the
* address of the RCC_AHB1ENR register, retrieves the current value of the register, sets the GPIOAEN bit,
* and stores the updated value back into the register.
*
* @param None
* @retval None
*/
GPIOA_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40023830 // load address of RCC_AHB1ENR register
LDR R5, [R4] // load value inside RCC_AHB1ENR register
ORR R5, #(1<<0) // set the GPIOAEN bit
STR R5, [R4] // store value into RCC_AHB1ENR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables the GPIOB peripheral by setting the corresponding RCC_AHB1ENR bit.
*
* @details This function enables the GPIOB peripheral by setting the corresponding RCC_AHB1ENR bit. It loads the
* address of the RCC_AHB1ENR register, retrieves the current value of the register, sets the GPIOBEN bit,
* and stores the updated value back into the register.
*
* @param None
* @retval None
*/
GPIOB_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40023830 // load address of RCC_AHB1ENR register
LDR R5, [R4] // load value inside RCC_AHB1ENR register
ORR R5, #(1<<1) // set the GPIOBEN bit
STR R5, [R4] // store value into RCC_AHB1ENR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables the GPIOC peripheral by setting the corresponding RCC_AHB1ENR bit.
*
* @details This function enables the GPIOC peripheral by setting the corresponding RCC_AHB1ENR bit. It loads the
* address of the RCC_AHB1ENR register, retrieves the current value of the register, sets the GPIOCEN bit,
* and stores the updated value back into the register.
*
* @param None
* @retval None
*/
GPIOC_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40023830 // load address of RCC_AHB1ENR register
LDR R5, [R4] // load value inside RCC_AHB1ENR register
ORR R5, #(1<<2) // set the GPIOCEN bit
STR R5, [R4] // store value into RCC_AHB1ENR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Configures GPIOA pin 2 to operate in alternate function mode.
*
* @details This function configures GPIOA pin 2 to operate in alternate function mode. It modifies the GPIOA_MODER
* and GPIOA_AFRL registers to set the necessary bits for alternate function mode on pin 2. The MODER2 bit
* is set to select alternate function mode, and the AFRL2 bits are set to specify the desired alternate
* function.
*
* @param None
* @retval None
*/
GPIOA_PA2_Alt_Function_Mode_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020000 // load address of GPIOA_MODER register
LDR R5, [R4] // load value inside GPIOA_MODER register
ORR R5, #(1<<5) // set the MODER2 bit
BIC R5, #(1<<4) // clear the MODER2 bit
STR R5, [R4] // store value into GPIOA_MODER register
LDR R4, =0x40020020 // load address of GPIOA_AFRL register
LDR R5, [R4] // load value inside GPIOA_AFRL register
BIC R5, #(1<<11) // clear the AFRL2 bit
ORR R5, #(1<<10) // set the AFRL2 bit
ORR R5, #(1<<9) // set the AFRL2 bit
ORR R5, #(1<<8) // set the AFRL2 bit
STR R5, [R4] // store value into GPIOA_AFRL register
POP {R4-R12, LR} // pop registers R4-R12 , LR from the stack
BX LR // return to caller
/**
* @brief Configures GPIOA pin 3 to operate in alternate function mode.
*
* @details This function configures GPIOA pin 3 to operate in alternate function mode. It modifies the GPIOA_MODER
* and GPIOA_AFRL registers to set the necessary bits for alternate function mode on pin 3. The MODER3 bit
* is set to select alternate function mode, and the AFRL3 bits are set to specify the desired alternate
* function.
*
* @param None
* @retval None
*/
GPIOA_PA3_Alt_Function_Mode_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020000 // load address of GPIOA_MODER register
LDR R5, [R4] // load value inside GPIOA_MODER register
ORR R5, #(1<<7) // set the MODER3 bit
BIC R5, #(1<<6) // clear the MODER3 bit
STR R5, [R4] // store value into GPIOA_MODER register
LDR R4, =0x40020020 // load address of GPIOA_AFRL register
LDR R5, [R4] // load value inside GPIOA_AFRL register
BIC R5, #(1<<15) // clear the AFRL3 bit
ORR R5, #(1<<14) // set the AFRL3 bit
ORR R5, #(1<<13) // set the AFRL3 bit
ORR R5, #(1<<12) // set the AFRL3 bit
STR R5, [R4] // store value into GPIOA_AFRL register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables Alternative Function Mode on GPIOB Pin 8.
*
* @details This assembly function enables the Alternative Function Mode on GPIOB Pin 8 by configuring the
* corresponding bits in the GPIOB_MODER and GPIOB_AFRH registers. It sets the pin to Alternative Function
* Mode and configures the specific alternative function for Pin 8.
*
* @param None
* @retval None
*/
GPIOB_PB8_Alt_Function_Mode_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020400 // load address of GPIOB_MODER register
LDR R5, [R4] // load value inside GPIOB_MODER register
ORR R5, #(1<<17) // set the MODER8 bit
BIC R5, #(1<<16) // clear the MODER8 bit
STR R5, [R4] // store value into GPIOB_MODER register
LDR R4, =0x40020424 // load address of GPIOB_AFRH register
LDR R5, [R4] // load value inside GPIOB_AFRH register
BIC R5, #(1<<3) // clear the AFRH8 bit
ORR R5, #(1<<2) // set the AFRH8 bit
BIC R5, #(1<<1) // clear the AFRH8 bit
BIC R5, #(1<<0) // clear the AFRH8 bit
STR R5, [R4] // store value into GPIOB_AFRH register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables Open Drain Mode on GPIOB Pin 8.
*
* @details This assembly function enables Open Drain Mode on GPIOB Pin 8 by setting the corresponding bit in the
* GPIOB_OTYPER register.
*
* @param None
* @retval None
*/
GPIOB_PB8_Open_Drain_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020404 // load address of GPIOB_OTYPER register
LDR R5, [R4] // load value inside GPIOB_OTYPER register
ORR R5, #(1<<8) // set the OT8 bit
STR R5, [R4] // store value into GPIOB_OTYPER register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables Alternative Function Mode on GPIOB Pin 9.
*
* @details This assembly function enables the Alternative Function Mode on GPIOB Pin 9 by configuring the
* corresponding bits in the GPIOB_MODER and GPIOB_AFRH registers. It sets the pin to Alternative Function
* Mode and configures the specific alternative function for Pin 9.
*
* @param None
* @retval None
*/
GPIOB_PB9_Alt_Function_Mode_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020400 // load address of GPIOB_MODER register
LDR R5, [R4] // load value inside GPIOB_MODER register
ORR R5, #(1<<19) // set the MODER9 bit
BIC R5, #(1<<18) // clear the MODER9 bit
STR R5, [R4] // store value into GPIOB_MODER register
LDR R4, =0x40020424 // load address of GPIOB_AFRH register
LDR R5, [R4] // load value inside GPIOB_AFRH register
BIC R5, #(1<<7) // clear the AFRH9 bit
ORR R5, #(1<<6) // set the AFRH9 bit
BIC R5, #(1<<5) // clear the AFRH9 bit
BIC R5, #(1<<4) // clear the AFRH9 bit
STR R5, [R4] // store value into GPIOB_AFRH register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables Open Drain Mode on GPIOB Pin 9.
*
* @details This assembly function enables Open Drain Mode on GPIOB Pin 9 by setting the corresponding bit in the
* GPIOB_OTYPER register.
*
* @param None
* @retval None
*/
GPIOB_PB9_Open_Drain_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020404 // load address of GPIOB_OTYPER register
LDR R5, [R4] // load value inside GPIOB_OTYPER register
ORR R5, #(1<<9) // set the OT9 bit
STR R5, [R4] // store value into GPIOB_OTYPER register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Configures GPIOB pin 0 to operate in input mode.
*
* @details This function configures GPIOB pin 0 to operate in input mode. It modifies the GPIOB_MODER register to
* set the necessary bits for input mode on pin 0. The MODER0 bit is set to input mode.
*
* @param None
* @retval None
*/
GPIOB_PB0_Input_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020400 // load address of GPIOB_MODER register
LDR R5, [R4] // load value inside GPIOB_MODER register
BIC R5, #(1<<1) // clear the MODER0 bit
BIC R5, #(1<<0) // clear the MODER0 bit
STR R5, [R4] // store value into GPIOB_MODER register
LDR R4, =0x4002040C // load address of GPIOB_PUPDR register
LDR R5, [R4] // load value inside GPIOB_PUPDR register
BIC R5, #(1<<1) // clear the PUPDR0 bit
ORR R5, #(1<<0) // set the PUPDR0 bit
STR R5, [R4] // store value into GPIOB_PUPDR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Configures GPIOB pin 1 to operate in input mode.
*
* @details This function configures GPIOB pin 1 to operate in input mode. It modifies the GPIOB_MODER register to
* set the necessary bits for input mode on pin 1. The MODER1 bit is set to input mode.
*
* @param None
* @retval None
*/
GPIOB_PB1_Input_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020400 // load address of GPIOB_MODER register
LDR R5, [R4] // load value inside GPIOB_MODER register
BIC R5, #(1<<3) // clear the MODER1 bit
BIC R5, #(1<<2) // clear the MODER1 bit
STR R5, [R4] // store value into GPIOB_MODER register
LDR R4, =0x4002040C // load address of GPIOB_PUPDR register
LDR R5, [R4] // load value inside GPIOB_PUPDR register
BIC R5, #(1<<3) // clear the PUPDR1 bit
ORR R5, #(1<<2) // set the PUPDR1 bit
STR R5, [R4] // store value into GPIOB_PUPDR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Configures GPIOB pin 2 to operate in input mode.
*
* @details This function configures GPIOB pin 2 to operate in input mode. It modifies the GPIOB_MODER register to
* set the necessary bits for input mode on pin 2. The MODER2 bit is set to input mode.
*
* @param None
* @retval None
*/
GPIOB_PB2_Input_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020400 // load address of GPIOB_MODER register
LDR R5, [R4] // load value inside GPIOB_MODER register
BIC R5, #(1<<5) // clear the MODER2 bit
BIC R5, #(1<<4) // clear the MODER2 bit
STR R5, [R4] // store value into GPIOB_MODER register
LDR R4, =0x4002040C // load address of GPIOB_PUPDR register
LDR R5, [R4] // load value inside GPIOB_PUPDR register
BIC R5, #(1<<5) // clear the PUPDR2 bit
ORR R5, #(1<<4) // set the PUPDR2 bit
STR R5, [R4] // store value into GPIOB_PUPDR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Configures GPIOB pin 3 to operate in input mode.
*
* @details This function configures GPIOB pin 3 to operate in input mode. It modifies the GPIOB_MODER register to
* set the necessary bits for input mode on pin 3. The MODER3 bit is set to input mode.
*
* @param None
* @retval None
*/
GPIOB_PB3_Input_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020400 // load address of GPIOB_MODER register
LDR R5, [R4] // load value inside GPIOB_MODER register
BIC R5, #(1<<7) // clear the MODER3 bit
BIC R5, #(1<<6) // clear the MODER3 bit
STR R5, [R4] // store value into GPIOB_MODER register
LDR R4, =0x4002040C // load address of GPIOB_PUPDR register
LDR R5, [R4] // load value inside GPIOB_PUPDR register
BIC R5, #(1<<7) // clear the PUPDR3 bit
ORR R5, #(1<<6) // set the PUPDR3 bit
STR R5, [R4] // store value into GPIOB_PUPDR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Configures GPIOB pin 4 to operate in input mode.
*
* @details This function configures GPIOB pin 4 to operate in input mode. It modifies the GPIOB_MODER register to
* set the necessary bits for input mode on pin 4. The MODER4 bit is set to input mode.
*
* @param None
* @retval None
*/
GPIOB_PB4_Input_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020400 // load address of GPIOB_MODER register
LDR R5, [R4] // load value inside GPIOB_MODER register
BIC R5, #(1<<9) // clear the MODER4 bit
BIC R5, #(1<<8) // clear the MODER4 bit
STR R5, [R4] // store value into GPIOB_MODER register
LDR R4, =0x4002040C // load address of GPIOB_PUPDR register
LDR R5, [R4] // load value inside GPIOB_PUPDR register
BIC R5, #(1<<9) // clear the PUPDR4 bit
ORR R5, #(1<<8) // set the PUPDR4 bit
STR R5, [R4] // store value into GPIOB_PUPDR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Configures GPIOB pin 5 to operate in input mode.
*
* @details This function configures GPIOB pin 5 to operate in input mode. It modifies the GPIOB_MODER register to
* set the necessary bits for input mode on pin 5. The MODER5 bit is set to input mode.
*
* @param None
* @retval None
*/
GPIOB_PB5_Input_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020400 // load address of GPIOB_MODER register
LDR R5, [R4] // load value inside GPIOB_MODER register
BIC R5, #(1<<11) // clear the MODER5 bit
BIC R5, #(1<<10) // clear the MODER5 bit
STR R5, [R4] // store value into GPIOB_MODER register
LDR R4, =0x4002040C // load address of GPIOB_PUPDR register
LDR R5, [R4] // load value inside GPIOB_PUPDR register
BIC R5, #(1<<11) // clear the PUPDR5 bit
ORR R5, #(1<<10) // set the PUPDR5 bit
STR R5, [R4] // store value into GPIOB_PUPDR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables USART2 peripheral and configures its settings for communication using an interrupt.
*
* @details This function enables the USART2 peripheral by setting the corresponding RCC_APB1ENR bit. It also
* configures the USART2 settings, including the baud rate and control register settings. The USART2_BRR
* register is set to achieve a baud rate of 9600, and the USART2_CR1 register is modified to enable USART2
* (UE bit) and receive interrupt (RXNEIE bit) and enable transmission (TE bit) and enable receive (RE bit).
*
* @param None
* @retval None
*/
USART2_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40023840 // load address of RCC_APB1ENR register
LDR R5, [R4] // load value inside RCC_APB1ENR register
ORR R5, #(1<<17) // set the USART2EN bit
STR R5, [R4] // store value into RCC_AHB1ENR register
LDR R4, =0x40004408 // load address of USART2_BRR register
LDR R5, [R4] // load value inside USART2_BRR register
MOV R5, #0x683 // set register to 9600 baud
STR R5, [R4] // store value into USART2_BRR register
LDR R4, =0x4000440C // load address of USART2_CR1 register
LDR R5, [R4] // load value inside USART2_CR1 register
ORR R5, #(1<<13) // set the UE bit
STR R5, [R4] // store value into USART2_CR1 register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Sends a single character over USART2.
*
* @details This function sends a single character over USART2 by writing it to the USART2_DR register. It first
* checks if the transmit buffer is empty (TXE bit) in the USART2_SR register. If the buffer is not empty,
* it waits until it becomes empty before writing the character to USART_DR.
*
* @param R0: The character to be sent over USART2.
* @retval None
*/
USART2_Transmit_Character:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R4, R0 // copy first arg into R4
LDR R5, =0x40004400 // load address of USART2_SR register
.USART2_Transmit_Character_Loop:
LDR R6, [R5] // load value inside USART2_SR register
AND R6, #(1<<7) // read TXE bit
CMP R6, #0x00 // test TX FIFO is not full
BEQ .USART2_Transmit_Character_Loop // branch if equal
LDR R5, =0x40004404 // load value inside USART2_DR register
STR R4, [R5] // store value into USART2_DR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Receives a character over USART2.
*
* @details This function receives a character over USART2 by reading the USART2_DR register. The received character
* is then returned.
*
* @param None
* @retval R0: The received character over USART2.
*/
USART2_Receive_Character:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40004400 // load address of USART2_SR register
.USART2_Receive_Character_Loop:
BL GPIOB_PB5_Read_Value // call function
CMP R0, #0x20 // check if button is pressed
BNE .USART2_Receive_Character_Exit // branch if not equal
LDR R5, [R4] // load value inside USART_SR register
AND R5, #(1<<5) // read the RXNE bit, if RXNE is 0, data is not recv
CMP R5, #0 // cmp RXNE bit to 0
BEQ .USART2_Receive_Character_Loop // branch if equal
LDR R4, =0x40004404 // load value inside USART2_DR register
LDRB R0, [R4] // load byte inside USART2_DR register
.USART2_Receive_Character_Exit:
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Clear USART2 buffer.
*
* This function clears the receive buffer of USART2 by reading the data register (USART2_DR)
* and discarding its content.
*
* @param None
* @retval None
*/
USART2_Clear_Buffer:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40004400 // load address of USART2_SR register
LDR R5, [R4] // load value inside USART_SR register
LDR R4, =0x40004404 // load value inside USART2_DR register
LDR R5, [R4] // load byte inside USART2_DR register
MOV R5, #0 // move zero into R5
STR R5, [R4] // store value into USART2_DR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enables I2C1 Peripheral.
*
* @details This assembly function enables the I2C1 peripheral by setting the corresponding bit in the RCC_APB1ENR
* register. It loads the address of the RCC_APB1ENR register, retrieves the current value of the register,
* sets the I2C1EN bit, and stores the updated value back into the register.
*
* @param None
* @retval None
*/
I2C1_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40023840 // load address of RCC_APB1ENR register
LDR R5, [R4] // load value inside RCC_APB1ENR register
ORR R5, #(1<<21) // set the I2C1EN bit
STR R5, [R4] // store value into RCC_APB1ENR register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Initializes and enables the I2C1 peripheral.
*
* @details This assembly function initializes and enables the I2C1 peripheral by configuring the relevant bits in
* the I2C1_CR1, I2C1_CR2, I2C1_CCR, and I2C1_TRISE registers. It performs a software reset, sets the
* frequency and duty cycle, configures the clock control register, sets the rise time, and finally, enables
* the I2C1 peripheral.
*
* @param None
* @retval None
*/
I2C1_Init:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40005400 // load address of I2C1_CR1 register
LDR R5, [R4] // load value inside I2C1_CR1 register
ORR R5, #(1<<15) // set the SWRST bit
STR R5, [R4] // store value into I2C1_CR1 register
BIC R5, #(1<<15) // clear the SWRST bit
STR R5, [R4] // store value into I2C1_CR1 register
LDR R4, =0x40005404 // load address of I2C1_CR2 register
LDR R5, [R4] // load value inside I2C1_CR2 register
ORR R5, #(1<<5) // set the FREQ bit
ORR R5, #(1<<4) // set the FREQ bit
BIC R5, #(1<<3) // clear the FREQ bit
BIC R5, #(1<<2) // clear the FREQ bit
ORR R5, #(1<<1) // set the FREQ bit
BIC R5, #(1<<0) // clear the FREQ bit
STR R5, [R4] // store value into I2C1_CR2 register
LDR R4, =0x4000541C // load address of I2C1_CCR register
LDR R5, [R4] // load value inside I2C1_CCR register
ORR R5, #(1<<15) // set the F/S bit
ORR R5, #(1<<14) // set the DUTY bit
ORR R5, #(1<<1) // set the CCR bit
STR R5, [R4] // store value into I2C1_CCR register
LDR R4, =0x40005420 // load address of I2C1_TRISE register
LDR R5, [R4] // load value inside I2C1_TRISE register
BIC R5, #(1<<5) // clear the TRISE bit
ORR R5, #(1<<4) // set the TRISE bit
BIC R5, #(1<<3) // clear the TRISE bit
ORR R5, #(1<<2) // set the TRISE bit
BIC R5, #(1<<1) // clear the TRISE bit
BIC R5, #(1<<0) // clear the TRISE bit
STR R5, [R4] // store value into I2C1_TRISE register
LDR R4, =0x40005400 // load address of I2C1_CR1 register
LDR R5, [R4] // load value inside I2C1_CR1 register
ORR R5, #(1<<0) // set the PE bit
STR R5, [R4] // store value into I2C1_CR1 register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Initializes the SSD1306 OLED Display.
*
* @details This assembly function initializes the SSD1306 OLED display by configuring the I2C communication
* parameters and sending the necessary commands to set up the display parameters.
*
* @param None
* @retval None
*/
SSD1306_Init:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
BL Thirty_Microsecond_Delay // call function
BL Thirty_Microsecond_Delay // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0x20 // set memory addressing mode, page addressing mode
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0xB0 // set page start address for page addressing mode (0-7 pages)
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0xA1 // set segment re-map, col addr 127 mapped to SEG0
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0xC8 // set COM output scan direction, remapped
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0x00 // set lower col start addr for page addr mode
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0x10 // set higher col start addr for page addr mode
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0xD5 // set display clock
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0xF0 // divide ratio/oscillator freq
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0x12 // set COM pins hardware config
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0xDB // set VCOMH deselect level
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0x20 // 0.77 VCC
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0x8D // charge pump setting
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0x14 // enable charge pump
BL I2C_Write_Byte // call function
BL SSD1306_Clear_Screen // call function
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Turns on the SSD1306 OLED Display.
*
* @details This assembly function turns on the SSD1306 OLED display by sending the necessary command through I2C
* communication to set the display panel to an active state.
*
* @param None
* @retval None
*/
SSD1306_Turn_On_Display:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0xAF // set display on
BL I2C_Write_Byte // call function
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Turns off the SSD1306 OLED Display.
*
* @details This assembly function turns off the SSD1306 OLED display by sending the necessary command through I2C
* communication to set the display panel to an inactive state.
*
* @param None
* @retval None
*/
SSD1306_Turn_Off_Display:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, #0xAE // set display off
BL I2C_Write_Byte // call function
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Sets the cursor position on the SSD1306 OLED Display.
*
* @details This assembly function sets the cursor position on the SSD1306 OLED display by sending the necessary
* commands through I2C communication. It specifies the lower and higher column start addresses along with
* the page start address to define the cursor position.
*
* @param R0: Lower column start address.
* @param R1: Higher column start address.
* @param R2: Page start address.
*
* @retval None
*/
SSD1306_Set_Cursor:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R4, R0 // copy first arg into R4
MOV R5, R1 // copy second arg into R5
MOV R6, R2 // copy third arg into R6
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, R4 // lower col start addr
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // command mode
MOV R2, R5 // higher col start addr
BL I2C_Write_Byte // call function
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x00 // memory addr
MOV R2, R6 // page start addr
BL I2C_Write_Byte // call function
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Clears the screen of the SSD1306 OLED Display.
*
* @details This assembly function clears the entire screen of the SSD1306 OLED display by sending the necessary
* commands and data through I2C communication. It utilizes the SSD1306_Set_Cursor function to position the
* cursor at the beginning of the display and then writes data to fill the screen with zeros.
*
* @param None
* @retval None
*/
SSD1306_Clear_Screen:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R0, #0x00 // lower col start addr
MOV R1, #0x10 // higher col start addr
MOV R2, #0xB0 // page start addr
BL SSD1306_Set_Cursor // call function
MOV R3, #0x00 // set counter
.SSD1306_Clear_Screen_Loop:
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x40 // data mode
MOV R2, #0 // data
BL I2C_Write_Byte // call function
ADD R3, #0x1 // increment counter
CMP R3, #0x480 // cmp if 0x480
BNE .SSD1306_Clear_Screen_Loop // branch not equal
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Displays a letter (character array) on the SSD1306 OLED Display.
*
* @details This assembly function displays a letter (character array) on the SSD1306 OLED display by utilizing the
* SSD1306_Set_Cursor function to position the cursor and then writing the letter data to the display memory
* through I2C communication. The function also calls the SSD1306_Turn_On_Display function to ensure the
* display is active.
*
* @param R0: Lower column start address.
* @param R1: Higher column start address.
* @param R2: Page start address.
* @param R3: Address of the character array to be displayed.
*
* @retval None
*/
SSD1306_Display_Letter:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R4, R0 // copy first arg into R4
MOV R5, R1 // copy second arg into R5
MOV R6, R2 // copy third arg into R6
MOV R7, R3 // copy fourth arg into R7
BL SSD1306_Set_Cursor // call function
MOV R8, #0 // set counter
.SSD1306_Display_Letter_Loop:
MOV R0, #0x3C // SSD1306 I2C addr
MOV R1, #0x40 // data mode
LDRB R2, [R7, R8] // load byte at addr in R7 and inc by counter
BL I2C_Write_Byte // call function
ADDS R8, #1 // increment counter
CMP R8, #6 // compare if end of array
BNE .SSD1306_Display_Letter_Loop // branch if not equal
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Writes a byte to the I2C device.
*
* @details This assembly function writes a byte to the I2C device. It waits for the device to be ready and sends the
* data byte using I2C communication.
*
* @param R0: I2C device address.
* @param R1: I2C data mode (0x00 for command, 0x40 for data).
* @param R2: Byte of data to be sent.
*
* @retval None
*/
I2C_Write_Byte:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R4, R0 // copy first arg into R4
MOV R5, R1 // copy second arg into R5
MOV R6, R2 // copy third arg into R6
.I2C_Wait_Not_Busy:
LDR R7, =0x40005418 // load address of I2C1_SR2 register
LDR R8, [R7] // load value inside I2C1_SR2 register
TST R8, #(1<<1) // read the BUSY bit, if 0, then BNE
BNE .I2C_Wait_Not_Busy // branch if not equal
LDR R7, =0x40005400 // load address of I2C1_CR1 register
LDR R8, [R7] // load value inside I2C1_CR1 register
ORR R8, #(1<<8) // set the START bit
ORR R8, #(1<<0) // set the PE bit
STR R8, [R7] // store value into I2C1_CR1 register
.I2C_Wait_Start:
LDR R7, =0x40005414 // load address of I2C1_SR1 register
LDR R8, [R7] // load value inside I2C1_SR1 register
TST R8, #(1<<0) // read the SB bit, if 1, then BEQ
BEQ .I2C_Wait_Start // branch if equal
LDR R7, =0x40005410 // load address of I2C1_DR register
LSL R4, #1 // left shift to make room for the rw bit
STR R4, [R7] // store value into I2C1_DR register
.I2C_Wait_Addr_Flag:
LDR R7, =0x40005414 // load address of I2C1_SR1 register
LDR R8, [R7] // load value inside I2C1_SR1 register
LDR R7, =0x40005414 // load address of I2C1_SR1 register
LDR R8, [R7] // load value inside I2C1_SR1 register
TST R8, #(1<<1) // read the ADDR bit, if 1, then BEQ
BEQ .I2C_Wait_Addr_Flag // branch if equal
LDR R7, =0x40005418 // load address of I2C1_SR2 register
LDR R8, [R7] // load value inside I2C1_SR2 register
STR R8, [R7] // store value into I2C1_SR2 register
.I2C_Wait_Data_Empty_Send_Mem_Addr:
LDR R7, =0x40005414 // load address of I2C1_SR1 register
LDR R8, [R7] // load value inside I2C1_SR1 register
TST R8, #(1<<7) // read the TxE bit, if 0, then BEQ
BEQ .I2C_Wait_Data_Empty_Send_Mem_Addr // branch if equal
LDR R7, =0x40005410 // load address of I2C1_DR register
STR R5, [R7] // store value into I2C1_DR register
.I2C_Wait_Data_Empty_Send_Data:
LDR R7, =0x40005414 // load address of I2C1_SR1 register
LDR R8, [R7] // load value inside I2C1_SR1 register
TST R8, #(1<<7) // read the TxE bit, if 1, then BNE
BEQ .I2C_Wait_Data_Empty_Send_Data // branch if equal
.I2C_Send_Data:
LDR R7, =0x40005410 // load address of I2C1_DR register
STR R6, [R7] // store value into I2C1_DR register
.I2C_Wait_Data_Transfer_Finished:
LDR R7, =0x40005414 // load address of I2C1_SR1 register
LDR R8, [R7] // load value inside I2C1_SR1 register
TST R8, #(1<<2) // read the BTF bit, if 0, then BEQ
BEQ .I2C_Wait_Data_Transfer_Finished // branch if equal
LDR R7, =0x40005400 // load address of I2C1_CR1 register
LDR R8, [R7] // load value inside I2C1_CR1 register
ORR R8, #(1<<9) // set the STOP bit
ORR R8, #(1<<0) // set the PE bit
STR R8, [R7] // store value into I2C1_CR1 register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Read the value of pin PB0.
*
* This function reads the value of pin PB0 (GPIO pin 0 of GPIO port B).
*
* @param None
* @retval uint32_t Value of pin PB0 (0 or 1)
*/
GPIOB_PB0_Read_Value:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020410 // load address of GPIOB_IDR register
LDR R0, [R4] // load value inside GPIOB_IDR register
AND R0, #(1<<0) // read the IDR0 bit
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Read the value of pin PB1.
*
* This function reads the value of pin PB1 (GPIO pin 1 of GPIO port B).
*
* @param None
* @retval uint32_t Value of pin PB1 (0 or 1)
*/
GPIOB_PB1_Read_Value:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020410 // load address of GPIOB_IDR register
LDR R0, [R4] // load value inside GPIOB_IDR register
AND R0, #(1<<1) // read the IDR1 bit
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Read the value of pin PB2.
*
* This function reads the value of pin PB2 (GPIO pin 2 of GPIO port B).
*
* @param None
* @retval uint32_t Value of pin PB2 (0 or 1)
*/
GPIOB_PB2_Read_Value:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020410 // load address of GPIOB_IDR register
LDR R0, [R4] // load value inside GPIOB_IDR register
AND R0, #(1<<2) // read the IDR2 bit
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Read the value of pin PB3.
*
* This function reads the value of pin PB3 (GPIO pin 3 of GPIO port B).
*
* @param None
* @retval uint32_t Value of pin PB3 (0 or 1)
*/
GPIOB_PB3_Read_Value:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020410 // load address of GPIOB_IDR register
LDR R0, [R4] // load value inside GPIOB_IDR register
AND R0, #(1<<3) // read the IDR3 bit
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Read the value of pin PB4.
*
* This function reads the value of pin PB4 (GPIO pin 4 of GPIO port B).
*
* @param None
* @retval uint32_t Value of pin PB4 (0 or 1)
*/
GPIOB_PB4_Read_Value:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020410 // load address of GPIOB_IDR register
LDR R0, [R4] // load value inside GPIOB_IDR register
AND R0, #(1<<4) // read the IDR4 bit
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Read the value of pin PB5.
*
* This function reads the value of pin PB5 (GPIO pin 5 of GPIO port B).
*
* @param None
* @retval uint32_t Value of pin PB5 (0 or 1)
*/
GPIOB_PB5_Read_Value:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x40020410 // load address of GPIOB_IDR register
LDR R0, [R4] // load value inside GPIOB_IDR register
AND R0, #(1<<5) // read the IDR5 bit
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enable USART2 transmission.
*
* This function enables transmission on USART2 by setting the TE bit in the USART2_CR1 register
* and clearing the RE bit to disable reception.
*
* @param None
* @retval None
*/
USART2_Transmit_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x4000440C // load address of USART2_CR1 register
LDR R5, [R4] // load value inside USART2_CR1 register
ORR R5, #(1<<3) // set the TE bit
STR R5, [R4] // store value into USART2_CR1 register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Enable USART2 reception.
*
* This function enables reception on USART2 by setting the RE bit in the USART2_CR1 register
* and clearing the TE bit to disable transmission.
*
* @param None
* @retval None
*/
USART2_Receive_Enable:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =0x4000440C // load address of USART2_CR1 register
LDR R5, [R4] // load value inside USART2_CR1 register
ORR R5, #(1<<2) // set the RE bit
STR R5, [R4] // store value into USART2_CR1 register
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Delay for approximately 30 microseconds.
*
* This function creates a delay of approximately 30 microseconds.
*
* @param None
* @retval None
*/
Thirty_Microsecond_Delay:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R4, #7 // number of loops
.Thirty_Microsecond_Delay_Outer_Loop:
MOV R5, #0xFFFF // set initial delay count
.Thirty_Microsecond_Delay_Inner_Loop:
SUB R5, #1 // decrement delay count
CMP R5, #0 // check if delay count reached zero
BNE .Thirty_Microsecond_Delay_Inner_Loop // continue loop if delay count not reached zero
SUB R4, #1 // decrement loop counter
CMP R4, #0 // check if delay count reached zero
BNE .Thirty_Microsecond_Delay_Outer_Loop // continue outer loop if more loops to go
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Menu selection loop.
*
* This function continuously checks for button inputs to perform menu actions.
* If GPIOB_PB0 is pressed, it generates a message.
* If GPIOB_PB1 is pressed, it receives, parses, and displays a message.
* After each action, the function clears the screen and returns to the menu loop.
*
* @param None
* @retval None
*/
Menu:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R0, #0x00 // lower col start addr
MOV R1, #0x11 // higher col start addr
MOV R2, #0xB0 // page start addr
LDR R3, =LETTER_M // load the address of array M
BL SSD1306_Display_Letter // call function
MOV R0, #0x00 // lower col start addr
MOV R1, #0x12 // higher col start addr
MOV R2, #0xB0 // page start addr
LDR R3, =LETTER_E // load the address of array E
BL SSD1306_Display_Letter // call function
MOV R0, #0x00 // lower col start addr
MOV R1, #0x13 // higher col start addr
MOV R2, #0xB0 // page start addr
LDR R3, =LETTER_N // load the address of array N
BL SSD1306_Display_Letter // call function
MOV R0, #0x00 // lower col start addr
MOV R1, #0x14 // higher col start addr
MOV R2, #0xB0 // page start addr
LDR R3, =LETTER_U // load the address of array U
BL SSD1306_Display_Letter // call function
MOV R0, #0x00 // lower col start addr
MOV R1, #0x11 // higher col start addr
MOV R2, #0xB3 // page start addr
LDR R3, =LETTER_T // load the address of array T
BL SSD1306_Display_Letter // call function
MOV R0, #0x00 // lower col start addr
MOV R1, #0x12 // higher col start addr
MOV R2, #0xB3 // page start addr
LDR R3, =LETTER_X // load the address of array X
BL SSD1306_Display_Letter // call function
MOV R0, #0x00 // lower col start addr
MOV R1, #0x11 // higher col start addr
MOV R2, #0xB5 // page start addr
LDR R3, =LETTER_R // load the address of array R
BL SSD1306_Display_Letter // call function
MOV R0, #0x00 // lower col start addr
MOV R1, #0x12 // higher col start addr
MOV R2, #0xB5 // page start addr
LDR R3, =LETTER_X // load the address of array X
BL SSD1306_Display_Letter // call function
.Menu_Select:
BL Thirty_Microsecond_Delay // call function
BL GPIOB_PB0_Read_Value // call function
CMP R0, #0x1 // check if button is pressed
BNE .Menu_Select_GPIOB_PB0_Button_Pressed // branch if not equal
BL GPIOB_PB1_Read_Value // call function
CMP R0, #0x2 // check if button is pressed
BNE .Menu_Select_GPIOB_PB1_Button_Pressed // branch if not equal
B .Menu_Select // call function
.Menu_Select_GPIOB_PB0_Button_Pressed:
BL SSD1306_Clear_Screen // call function
BL Generate_Message // call function
B .Menu_Exit // branch
.Menu_Select_GPIOB_PB1_Button_Pressed:
BL SSD1306_Clear_Screen // call function
BL Receive_Message // call function
BL Parse_Message // call function
BL Display_Message // call function
B .Menu_Exit // branch
.Menu_Exit:
BL SSD1306_Clear_Screen // call function
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Generate a message based on button inputs.
*
* This function generates a message based on button inputs and sends it through USART2.
*
* @param None
* @retval None
*/
Generate_Message:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
BL USART2_Clear_Buffer // call function
BL Thirty_Microsecond_Delay // call function
BL Thirty_Microsecond_Delay // call function
MOV R4, #0 // set array index to zero
MOV R5, #0x11 // higher col start addr
LDR R6, =LETTERS_ARRAY // load the address of array
MOV R7, #0 // set array pointer
LDR R8, =message_transmit_array // load addr of message array
MOV R9, #0 // set current char
MOV R10, #0x11 // set left of screen
MOV R11, #0x15 // set right of screen
MOV R12, #0xB0 // page start addr
.Generate_Message_Loop:
BL Thirty_Microsecond_Delay // call function
BL GPIOB_PB0_Read_Value // call function
CMP R0, #0x1 // check if button is pressed
BNE .Generate_Message_GPIOB_PB0_Button_Pressed // branch if not equal
BL GPIOB_PB1_Read_Value // call function
CMP R0, #0x2 // check if button is pressed
BNE .Generate_Message_GPIOB_PB1_Button_Pressed // branch if not equal
BL GPIOB_PB2_Read_Value // call function
CMP R0, #0x4 // check if button is pressed
BNE .Generate_Message_GPIOB_PB2_Button_Pressed // branch if not equal
BL GPIOB_PB3_Read_Value // call function
CMP R0, #0x8 // check if button is pressed
BNE .Generate_Message_GPIOB_PB3_Button_Pressed // branch if not equal
BL GPIOB_PB4_Read_Value // call function
CMP R0, #0x10 // check if button is pressed
BNE .Generate_Message_GPIOB_PB4_Button_Pressed // branch if not equal
BL GPIOB_PB5_Read_Value // call function
CMP R0, #0x20 // check if button is pressed
BNE .Generate_Message_GPIOB_PB5_Button_Pressed // branch if not equal
B .Generate_Message_Loop // branch
.Generate_Message_GPIOB_PB0_Button_Pressed:
BL Thirty_Microsecond_Delay // call function
CMP R5, R11 // check if we are at right of screen
BEQ .Generate_Message_Exit // branch if equal
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R12 // page start addr
LDR R3, [R6, R4, LSL #2] // load the char based on index in R6
LDRB R9, [R3, #6] // move current char byte at addr into R9
BL SSD1306_Display_Letter // call function
ADD R4, #1 // increment index
CMP R4, #26 // check if end of array is reached
BNE .Generate_Message_Loop // if not, continue loop
MOV R4, #0 // reset index to 0 when end of array is reached
B .Generate_Message_Loop // continue loop
.Generate_Message_GPIOB_PB1_Button_Pressed:
BL Thirty_Microsecond_Delay // call function
CMP R5, R11 // check if we are at right of screen
BEQ .Generate_Message_Exit // branch if equal
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R12 // page start addr
LDR R3, [R6, R4, LSL #2] // load the char based on index in R6
LDRB R9, [R3, #6] // move current char byte at addr into R9
BL SSD1306_Display_Letter // call function
SUB R4, #1 // increment index
CMP R4, #-1 // check if end of array is reached
BNE .Generate_Message_Loop // if not, continue loop
MOV R4, #25 // reset index to array end
B .Generate_Message_Loop // continue loop
.Generate_Message_GPIOB_PB2_Button_Pressed:
BL Thirty_Microsecond_Delay // call function
CMP R5, R11 // check if we are at right of screen
BEQ .Generate_Message_Loop // branch if equal
STR R9, [R8, R7] // store char in the array at index in R4
ADD R5, #1 // increment page addr
ADD R7, #1 // increment array pointer
B .Generate_Message_Loop // continue loop
.Generate_Message_GPIOB_PB3_Button_Pressed:
BL Thirty_Microsecond_Delay // call function
CMP R5, R10 // check if we are at left of screen
BEQ .Generate_Message_Loop // branch if equal
STR R9, [R8, R7] // store char in the array at index in R4
SUB R5, #1 // increment page addr
ADD R7, #1 // increment array pointer
B .Generate_Message_Loop // continue loop
.Generate_Message_GPIOB_PB4_Button_Pressed:
BL Thirty_Microsecond_Delay // call function
MOV R5, #0 // init index for the array
MOV R6, #4 // array length
.Generate_Message_Send_Char_Loop:
CMP R5, R6 // compare current index with array length
BEQ .Generate_Message_Exit // branch if equal
LDRB R7, [R8, R5] // load addr from the array at index R5
MOV R0, #0x41 // 'A'
BL USART2_Transmit_Character // call function
MOV R0, #0x54 // 'T'
BL USART2_Transmit_Character // call function
MOV R0, #0x2B // '+'
BL USART2_Transmit_Character // call function
MOV R0, #0x53 // 'S'
BL USART2_Transmit_Character // call function
MOV R0, #0x45 // 'E'
BL USART2_Transmit_Character // call function
MOV R0, #0x4E // 'N'
BL USART2_Transmit_Character // call function
MOV R0, #0x44 // 'D'
BL USART2_Transmit_Character // call function
MOV R0, #0x3D // '='
BL USART2_Transmit_Character // call function
MOV R0, #0x30 // '0'
BL USART2_Transmit_Character // call function
MOV R0, #0x2C // ','
BL USART2_Transmit_Character // call function
MOV R0, #0x31 // '1'
BL USART2_Transmit_Character // call function
MOV R0, #0x2C // ','
BL USART2_Transmit_Character // call function
MOV R0, R7 // current char at array position in R7
BL USART2_Transmit_Character // call function
MOV R0, #0xD // '\r'
BL USART2_Transmit_Character // call function
MOV R0, #0xA // '\n'
BL USART2_Transmit_Character // call function
ADD R5, #1 // increment index
BL Thirty_Microsecond_Delay // call function
BL Thirty_Microsecond_Delay // call function
BL Thirty_Microsecond_Delay // call function
BL Thirty_Microsecond_Delay // call function
B .Generate_Message_Send_Char_Loop // branch
.Generate_Message_GPIOB_PB5_Button_Pressed:
BL Thirty_Microsecond_Delay // call function
B .Generate_Message_Exit // branch
.Generate_Message_Exit:
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Receive a message.
*
* This function receives a message character by character through USART2 and stores it in the
* message full receive array.
*
* @param None
* @retval None
*/
Receive_Message:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =message_full_receive_array // load addr of message full receive array
MOV R5, #-1 // set counter
.Receive_Message_Loop:
CMP R5, #75 // compare if at end of our recv buffer
BEQ .Receive_Message_Exit // branch if equal
ADD R5, #1 // increment counter
BL USART2_Receive_Character // call function
STRB R0, [R4, R5] // store char into message_full_receive_array, offset R5
B .Receive_Message_Loop // branch
.Receive_Message_Exit:
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Parse a received message.
*
* This function parses a received message stored in the message_full_receive_array
* and extracts specific characters to store in the message parsed receive array.
*
* @param None
* @retval None
*/
Parse_Message:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =message_full_receive_array // load addr of message full receive array
LDR R5, =message_parsed_receive_array // load addr of message parsed receive array
MOV R7, #2 // set counter
.Parse_Message_Check_Third_Byte:
LDRB R6, [R4, R7] // load first byte into R6
CMP R6, #0x43 // check to make sure it is 'C'
BEQ .Parse_Message_Loop // branch if equal
ADD R7, #1 // increment counter
B .Parse_Message_Check_Third_Byte // branch
.Parse_Message_Loop:
ADD R8, R7, #7 // increment counter to get first correct character
LDRB R6, [R4, R8] // load offset of message full receive array
STRB R6, [R5, #0] // store byte message_parsed_receive_array
ADD R8, R7, #26 // increment counter to get second correct character
LDRB R6, [R4, R8] // load offset 28 of message full receive array
STRB R6, [R5, #1] // store byte message_parsed_receive_array
ADD R8, R7, #45 // increment counter to get second correct character
LDRB R6, [R4, R8] // load offset of message full receive array
STRB R6, [R5, #2] // store byte message_parsed_receive_array
ADD R8, R7, #64 // increment counter to get second correct character
LDRB R6, [R4, R8] // load offset of message full receive array
STRB R6, [R5, #3] // store byte message_parsed_receive_array
.Parse_Message_Exit:
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Display a received message.
*
* This function displays a received message on an SSD1306 OLED display. It iterates through the characters
* of the message and calls a function to display each character on the OLED screen.
*
* @param None
* @retval None
*/
Display_Message:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
LDR R4, =message_parsed_receive_array // load addr of message parsed receive array
MOV R5, #0x14 // set counter
MOV R6, #-1 // set counter
MOV R7, #0xB1 // page start addr
MOV R8, #0x19 // set right of screen
.Display_Message_Loop:
CMP R6, #3 // compare if at end of our message parsed recv buffer
BEQ .Display_Message_Until_Exit // branch if equal
ADD R6, #1 // increment counter
LDRB R0, [R4, R6] // load byte in message parsed receive array offset R6
CMP R0, 0x41 // compare 'A'
BEQ .Display_Message_Letter_A // branch if equal
CMP R0, 0x42 // compare 'B'
BEQ .Display_Message_Letter_B // branch if equal
CMP R0, 0x43 // compare 'C'
BEQ .Display_Message_Letter_C // branch if equal
CMP R0, 0x44 // compare 'D'
BEQ .Display_Message_Letter_D // branch if equal
CMP R0, 0x45 // compare 'E'
BEQ .Display_Message_Letter_E // branch if equal
CMP R0, 0x46 // compare 'F'
BEQ .Display_Message_Letter_F // branch if equal
CMP R0, 0x47 // compare 'G'
BEQ .Display_Message_Letter_G // branch if equal
CMP R0, 0x48 // compare 'H'
BEQ .Display_Message_Letter_H // branch if equal
CMP R0, 0x49 // compare 'I'
BEQ .Display_Message_Letter_I // branch if equal
CMP R0, 0x4A // compare 'J'
BEQ .Display_Message_Letter_J // branch if equal
CMP R0, 0x4B // compare 'K'
BEQ .Display_Message_Letter_K // branch if equal
CMP R0, 0x4C // compare 'L'
BEQ .Display_Message_Letter_L // branch if equal
CMP R0, 0x4D // compare 'M'
BEQ .Display_Message_Letter_M // branch if equal
CMP R0, 0x4E // compare 'N'
BEQ .Display_Message_Letter_N // branch if equal
CMP R0, 0x4F // compare 'O'
BEQ .Display_Message_Letter_O // branch if equal
CMP R0, 0x50 // compare 'P'
BEQ .Display_Message_Letter_P // branch if equal
CMP R0, 0x51 // compare 'Q'
BEQ .Display_Message_Letter_Q // branch if equal
CMP R0, 0x52 // compare 'R'
BEQ .Display_Message_Letter_R // branch if equal
CMP R0, 0x53 // compare 'S'
BEQ .Display_Message_Letter_S // branch if equal
CMP R0, 0x54 // compare 'T'
BEQ .Display_Message_Letter_T // branch if equal
CMP R0, 0x55 // compare 'U'
BEQ .Display_Message_Letter_U // branch if equal
CMP R0, 0x56 // compare 'V'
BEQ .Display_Message_Letter_V // branch if equal
CMP R0, 0x57 // compare 'W'
BEQ .Display_Message_Letter_W // branch if equal
CMP R0, 0x58 // compare 'X'
BEQ .Display_Message_Letter_X // branch if equal
CMP R0, 0x59 // compare 'Y'
BEQ .Display_Message_Letter_Y // branch if equal
CMP R0, 0x5A // compare 'Z'
BEQ .Display_Message_Letter_Z // branch if equal
CMP R0, 0x00 // compare null
BEQ .Display_Message_LETTER_NULL // branch if equal
.Display_Message_Letter_A:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_A // load the address of array A
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_B:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_B // load the address of array B
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_C:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_C // load the address of array C
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_D:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_D // load the address of array D
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_E:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_E // load the address of array E
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_F:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_F // load the address of array F
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_G:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_G // load the address of array G
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_H:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_H // load the address of array H
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_I:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_I // load the address of array I
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_J:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_J // load the address of array J
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_K:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_K // load the address of array K
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_L:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_L // load the address of array L
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_M:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_M // load the address of array M
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_N:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_N // load the address of array N
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_O:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_O // load the address of array O
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_P:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_P // load the address of array P
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_Q:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_Q // load the address of array Q
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_R:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_R // load the address of array R
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_S:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_S // load the address of array S
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_T:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_T // load the address of array T
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_U:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_U // load the address of array U
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_V:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_V // load the address of array V
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_W:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_W // load the address of array W
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_X:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_X // load the address of array X
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_Y:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_Y // load the address of array Y
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Letter_Z:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_Z // load the address of array Z
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_LETTER_NULL:
MOV R0, #0x00 // lower col start addr
MOV R1, R5 // higher col start addr
MOV R2, R7 // page start addr
LDR R3, =LETTER_NULL // load the address of array Z
BL SSD1306_Display_Letter // call function
CMP R5, R8 // check if we are at right of screen
BNE .Display_Message_Add_Higher_Col_Value // branch if not equal
B .Display_Message_Loop // branch
.Display_Message_Add_Higher_Col_Value:
ADD R5, #1 // increment higher col addr
B .Display_Message_Loop // branch
.Display_Message_Until_Exit:
BL GPIOB_PB5_Read_Value // call function
CMP R0, #0x20 // check if button is pressed
BNE .Display_Message_Exit // branch if not equal
B .Display_Message_Until_Exit // branch
.Display_Message_Exit:
MOV R5, #0x11 // higher col start addr
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Initialize LoRa module setup.
*
* This function sets up the LoRa module by transmitting specific commands via USART2 for configuration.
*
* @param None
* @retval None
*/
LoRa_Setup:
PUSH {R4-R12, LR} // push registers R4-R12, LR to the stack
MOV R0, #0x41 // 'A'
BL USART2_Transmit_Character // call function
MOV R0, #0x54 // 'T'
BL USART2_Transmit_Character // call function
MOV R0, #0x2B // '+'
BL USART2_Transmit_Character // call function
MOV R0, #0x49 // 'I'
BL USART2_Transmit_Character // call function
MOV R0, #0x50 // 'P'
BL USART2_Transmit_Character // call function
MOV R0, #0x52 // 'R'
BL USART2_Transmit_Character // call function
MOV R0, #0x3D // '='
BL USART2_Transmit_Character // call function
MOV R0, #0x39 // '9'
BL USART2_Transmit_Character // call function
MOV R0, #0x36 // '6'
BL USART2_Transmit_Character // call function
MOV R0, #0x30 // '0'
BL USART2_Transmit_Character // call function
MOV R0, #0x30 // '0'
BL USART2_Transmit_Character // call function
MOV R0, #0xD // '\r'
BL USART2_Transmit_Character // call function
MOV R0, #0xA // '\n'
BL USART2_Transmit_Character // call function
MOV R0, #0x41 // 'A'
BL USART2_Transmit_Character // call function
MOV R0, #0x54 // 'T'
BL USART2_Transmit_Character // call function
MOV R0, #0x2B // '+'
BL USART2_Transmit_Character // call function
MOV R0, #0x41 // 'A'
BL USART2_Transmit_Character // call function
MOV R0, #0x44 // 'D'
BL USART2_Transmit_Character // call function
MOV R0, #0x44 // 'D'
BL USART2_Transmit_Character // call function
MOV R0, #0x52 // 'R'
BL USART2_Transmit_Character // call function
MOV R0, #0x45 // 'E'
BL USART2_Transmit_Character // call function
MOV R0, #0x53 // 'S'
BL USART2_Transmit_Character // call function
MOV R0, #0x53 // 'S'
BL USART2_Transmit_Character // call function
MOV R0, #0x3D // '='
BL USART2_Transmit_Character // call function
MOV R0, #0x30 // '0'
BL USART2_Transmit_Character // call function
MOV R0, #0xA // '\r'
BL USART2_Transmit_Character // call function
MOV R0, #0xD // '\n'
BL USART2_Transmit_Character // call function
POP {R4-R12, LR} // pop registers R4-R12, LR from the stack
BX LR // return to caller
/**
* @brief Infinite loop function.
*
* This function implements an infinite loop using an unconditional branch, B, statement. It is designed to
* keep the program running indefinitely by branching back to itself.
*
* @param None
* @retval None
*/
Loop:
BL Menu // call function
B Loop // infinite loop
/**
* Initialize the .rodata section. The .rodata section is used for constants and static strings.
*/
.section .rodata
LETTERS_ARRAY:
.word LETTER_A
.word LETTER_B
.word LETTER_C
.word LETTER_D
.word LETTER_E
.word LETTER_F
.word LETTER_G
.word LETTER_H
.word LETTER_I
.word LETTER_J
.word LETTER_K
.word LETTER_L
.word LETTER_M
.word LETTER_N
.word LETTER_O
.word LETTER_P
.word LETTER_Q
.word LETTER_R
.word LETTER_S
.word LETTER_T
.word LETTER_U
.word LETTER_V
.word LETTER_W
.word LETTER_X
.word LETTER_Y
.word LETTER_Z
LETTER_A:
.byte 0x00, 0x7C, 0x12, 0x11, 0x12, 0x7C, 0x41
LETTER_B:
.byte 0x00, 0x7F, 0x49, 0x49, 0x49, 0x36, 0x42
LETTER_C:
.byte 0x00, 0x3E, 0x41, 0x41, 0x41, 0x22, 0x43
LETTER_D:
.byte 0x00, 0x7F, 0x41, 0x41, 0x22, 0x1C, 0x44
LETTER_E:
.byte 0x00, 0x7F, 0x49, 0x49, 0x49, 0x41, 0x45
LETTER_F:
.byte 0x00, 0x7F, 0x09, 0x09, 0x09, 0x01, 0x46
LETTER_G:
.byte 0x00, 0x3E, 0x41, 0x49, 0x49, 0x7A, 0x47
LETTER_H:
.byte 0x00, 0x7F, 0x08, 0x08, 0x08, 0x7F, 0x48
LETTER_I:
.byte 0x00, 0x00, 0x41, 0x7F, 0x41, 0x00, 0x49
LETTER_J:
.byte 0x00, 0x20, 0x40, 0x41, 0x3F, 0x01, 0x4A
LETTER_K:
.byte 0x00, 0x7F, 0x08, 0x14, 0x22, 0x41, 0x4B
LETTER_L:
.byte 0x00, 0x7F, 0x40, 0x40, 0x40, 0x40, 0x4C
LETTER_M:
.byte 0x00, 0x7F, 0x02, 0x0C, 0x02, 0x7F, 0x4D
LETTER_N:
.byte 0x00, 0x7F, 0x04, 0x08, 0x10, 0x7F, 0x4E
LETTER_O:
.byte 0x00, 0x3E, 0x41, 0x41, 0x41, 0x3E, 0x4F
LETTER_P:
.byte 0x00, 0x7F, 0x09, 0x09, 0x09, 0x06, 0x50
LETTER_Q:
.byte 0x00, 0x3E, 0x41, 0x51, 0x21, 0x5E, 0x51
LETTER_R:
.byte 0x00, 0x7F, 0x09, 0x19, 0x29, 0x46, 0x52
LETTER_S:
.byte 0x00, 0x46, 0x49, 0x49, 0x49, 0x31, 0x53
LETTER_T:
.byte 0x00, 0x01, 0x01, 0x7F, 0x01, 0x01, 0x54
LETTER_U:
.byte 0x00, 0x3F, 0x40, 0x40, 0x40, 0x3F, 0x55
LETTER_V:
.byte 0x00, 0x1F, 0x20, 0x40, 0x20, 0x1F, 0x56
LETTER_W:
.byte 0x00, 0x3F, 0x40, 0x38, 0x40, 0x3F, 0x57
LETTER_X:
.byte 0x00, 0x63, 0x14, 0x08, 0x14, 0x63, 0x58
LETTER_Y:
.byte 0x00, 0x07, 0x08, 0x70, 0x08, 0x07, 0x59
LETTER_Z:
.byte 0x00, 0x61, 0x51, 0x49, 0x45, 0x43, 0x5A
LETTER_NULL:
.byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
/**
* Initialize the .data section. The .data section is used for initialized global or static variables.
*/
.section .data
message_transmit_array:
.space 4
message_full_receive_array:
.space 76
message_parsed_receive_array:
.space 4
/**
* Initialize the .bss section. The .bss section is typically used for uninitialized global or static variables.
*/
.section .bss