Awesome

vi2c

vi2c is a tiny I2C communication library written in V.

Documentation

struct I2CDevice

Represents an I2C device. Fields:

• m_fd (int): File descriptor (-1 if not open).
• m_name (string): Name of the device.
• m_device_address (u8): I2C device address.
• m_device_filename (string): File path of the I2C device.
• m_is_connected (bool): Indicates if the device is connected.
• m_is_forced (bool): Indicates if the connection was forced.
• m_is_10bit (bool): true if 10 bit address, otherwise 7 bit address.

Functions

Function new(filename string, address u8, name string, is_10bit bool) I2CDevice

Creates a new I2CDevice instance.

• filename (string): File path of the I2C device.
• address (u8): I2C device address.
• name (string): Name of the device.
• is_10bit (bool): true if 10 bit address, otherwise 7 bit address.

Function connect(force_connection bool) bool

Connects to the I2C device.

• force_connection (bool): Indicates if the connection should be forced. Force (or not) using this slave address, even if it is already in use by a driver.

Returns true if the connection is successful, otherwise false.

Function read_data(max_length int) (int, []u8)

Reads data from the I2C device.

• max_length (int): Maximum length of data to read.

Returns the number of bytes read and the data as a byte slice.

Function write_data(data []u8) u32

Writes data to the I2C device.

• data ([]u8): Data to write.

Returns the number of bytes written.

Function read_data_from_reg(reg u8, max_length int) (int, []u8)

Reads data from a register of the I2C device.

• reg (u8): Register address to read from.
• max_length (int): Maximum length of data to read.

Returns the number of bytes read and the data as a byte slice.

Function read_reg(reg u8) (int, []u8)

Reads a register from the I2C device.

• reg (u8): Register address to read.

Returns the value read from the register as a byte slice.

Function write_reg_data(reg u8, data []u8) u32

Writes data to a register of the I2C device.

• reg (u8): Register address to write to.
• data ([]u8): Data to write.

Returns the number of bytes written.

Function write_reg(reg u8, value u8) u32

Writes a value to a register of the I2C device.

• reg (u8): Register address to write to.
• value (u8): Value to write.

Returns the number of bytes written.

Function disconnect()

Disconnects from the I2C device.

Function is_forced() bool

Checks if the connection to the I2C device was forced. Returns true if the connection was forced, otherwise false.

Functon is_connected() bool

Checks if the connection to the I2C device is established. Returns true if connected, otherwise false.

Function name() string

Gets the name of the I2C device. Returns the name of the device.

Function filename() string

Gets the file path of the I2C device. Returns the file path of the device.

Function address() u8

Gets the address of the I2C device. Returns the address of the device.

Function fd() int

Gets the file descriptor of the I2C device. Returns the file descriptor.

Function set_retries(retries int) bool

Sets the number of retries for I2C communication.

• retries (int): The number of retries to set.

Returns (bool): true if the retries were successfully set, otherwise false.

Function set_timeout(timeout_ms int) bool

Sets the timeout for I2C communication.

• timeout_ms (int): Timeout value in milliseconds.

Returns (bool): true if the timeout was successfully set, otherwise false.

Function is_10bit() bool

Checks if the I2C device address is 10-bit. Returns (bool): true if the I2C device address is 10-bit, otherwise false.

Function str() string

Returns a formatted string representing the I2C device.

Example

module main

import time
import vi2c

fn main() {
	mut ic2_dev := vi2c.new('/dev/i2c-9', 0x48, 'Temp sensor')

	println(ic2_dev)

	if !ic2_dev.connect(true) {
		println('Failed to connect')
		return
	}

	println(ic2_dev)

	for _ in 1 .. 100 {
		len, data := ic2_dev.read_data_from_reg(~0, 2)

		if len == 2 {
			val := 0.00390625 * f32(u32(data[0]) << 8 | u32(data[1]))
			println('data: <${data.hex()}> temp: ${val} *C')
		}
		time.sleep(1000000000)
	}

	ic2_dev.disconnect()
}

Compile

cd ~/.vmodules
cd vi2c/playground/

To compile it for Linux host machine (x64/x86-64), make sure to specify the include path:

v -cflags '-I /usr/include/' . -o test_i2c_comm_x64

To cross-compile it for Aarch64, make sure that aarch64-linux-gnu-gcc and corresponding libraries are installed. Set aarch64-linux-gnu-gcc as -cc compiler, disable and add the include of Aarch64 - in this case /usr/aarch64-linux-gnu/include/.

v -cc aarch64-linux-gnu-gcc -gc none -cflags '--static -I /usr/aarch64-linux-gnu/include/' test_i2c_comm.v -o test_i2c_comm_aa64

NOTE: Please note that the library and the example code are tested in my Ubuntu 20.4 and an Aarch64 machine.