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Optimized TM1638 library for Arduino

This is a 3-pin serial TM1638 chip library for Arduino, optimized for size and speed. It supports a combined LED driver controller and key-scan interface to detect multiple key presses at the same time.

Displaying numbers, characters and reading keys depends on the hardware wiring and is not part of this library. A fully operational example for a board with 8 7-segment displays, 8 dual color LED's and 8 buttons which uses this library is available here: JY-LKM1638.

Hardware

Connect power and 3 data pins to an Arduino board DIGITAL pins:

• VDD (Power 3.3V - 5V)
• GND (Ground)
• DIO (Bi-directional data input/output)
• STB (Chip select)
• CLK (Clock)

The following TM1638 pins should be connected to LED's and buttons in a matrix:

• K1~K3 (Key-scan data input to read multiple key presses at the same time)
• SEG/GRID (Output for LED matrix)

Pins

• Check maximum regulator / diode current to prevent a burnout when using lots of LED's. Some boards can provide only 100mA, others 800mA max.

Example

Arduino IDE | Examples | Erriez TM1638 button and LED driver:

• ErriezTM1638

Documentation

• Doxygen online HTML
• Doxygen PDF
• TM1638 Datasheet

Usage

Initialization

// Include TM1638 library
#include <ErriezTM1638.h>

// Connect display pins to the Arduino DIGITAL pins
#define TM1638_CLK_PIN   2
#define TM1638_DIO_PIN   3
#define TM1638_STB_PIN   4

// Create tm1638 object
TM1638 tm1638(TM1638_CLK_PIN, TM1638_DIO_PIN, TM1638_STB_PIN);

void setup()
{
    // Initialize TM1638
    tm1638.begin();
}

Display on/off

// Turn display off
tm1638.displayOff();
  
// Turn display on
tm1638.displayOn();

Turn all LED's off

// Turn all LED's off
tm1638.clear();

Get keys

// Get 32-bit key-scan
uint32_t keys = tm1638.getKeys();

Write Byte to display register

// Write segment LED's to the first display registers 0x00..0x0F with value 0x00..0xff to
// display numbers and characters. Just an example which depends on the hardware:
tm1638.writeData(0x01, 0x01);

Write buffer to display registers

// Creat buffer with LED's
uint8_t buf[] = { 0b10000110, 0b00111111, 0b00111111, 0b00111111, 0b00111111, 0b00111111};

// Write buffer to TM1638
tm1638.writeData(0x00, buf, sizeof(buf));

Small footprint

Measured with Arduino IDE v1.8.5 without any other peripherals, calling all library functions once:

Optimized timing

The library uses optimized pin control for AVR targets. Other targets uses the default digitalRead() and digitalWrite() pin control functions.

Output Benchmark example:

Arduino UNO 16MHz

WeMos D1 & R2 80MHz

WeMos D1 & R2 160MHz

Library dependencies

• The ErriezTM1638Benchmark example uses Erriez Timestamp library.

Library installation

Please refer to the Wiki page.

Other Arduino Libraries and Sketches from Erriez

• Erriez Libraries and Sketches