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Optimized TM1637 library for Arduino

This is a 2-pin serial TM1637 chip library for Arduino, optimized for size and speed. It supports a combined LED driver controller and key-scan interface to detect one key press.

TM1637 chip

Chip features

Power CMOS process
Display mode (8 segments × 6 digits), support common anode LED output
Key scan (8 x 2-bit), enhanced anti-jamming button recognition circuit
Brightness adjustment circuit (adjustable duty cycle 8)
Two-wire serial interface (CLK, DIO)
Oscillation mode: Built-in RC oscillator
Built-in power-on reset circuit
Built-in automatic blanking circuit
Package: DIP20 / SOP20

Hardware

Connect power and 2 data pins to an Arduino board DIGITAL pins:

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

The following TM1637 pins should be connected to LED's and buttons in a matrix:

K1~K2 (Key-scan data input to read one key press after each other)
SEG/GRID (Output for LED matrix)

Pins

Pin	TM1637	Arduino UNO / Nano / Micro / Pro Micro / Leonardo / Mega2560	WeMos D1 & R2 / Node MCU	WeMos LOLIN32
1	VCC	5V (or 3.3V)	3V3	3V3
2	GND	GND	GND	GND
3	CLK	2 (DIGITAL pin)	D2	0
4	DIO	3 (DIGITAL pin)	D3	4

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

Two-wire serial interface

The TM1637 communicates with a MCU serial by using two wires:

DIO (bi-directional input/output pin)
SCL (Clock pin)

Note: The serial interface is not compatible with I2C or TWI, because no device address with read/write bit is used.

Example

Arduino IDE | Examples | Erriez TM1637 button and LED driver:

ErriezTM1637

Documentation

Usage

Initialization

// Include TM1637 library
#include <ErriezTM1637.h>
  
// Connect display pins to the Arduino DIGITAL pins
#define TM1637_CLK_PIN   2
#define TM1637_DIO_PIN   3

// Create tm1637 object
TM1637 tm1637(TM1637_CLK_PIN, TM1637_DIO_PIN);

void setup()
{
    // Initialize TM1637
    tm1637.begin();
}

Display on/off

// Turn display off
tm1637.displayOff();
  
// Turn display on
tm1637.displayOn();

Turn all LED's off

// Turn all LED's off
tm1637.clear();

Get keys

// Get 8-bit key-scan
uint8_t keys = tm1637.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:
tm1637.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 TM1637
tm1637.writeData(0x00, buf, sizeof(buf));

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:

Board	CLK	Read keys	Write Byte	Write 16 Bytes buffer	Clear display
Pro Mini 8MHz	84kHz	352us	344us	1080us	1072us
UNO 16MHz	170kHz	156us	152us	496us	480us
WeMos D1 & R2 80MHz	205kHz	261us	137us	396us	396us
WeMos D1 & R2 160MHz	300kHz	233us	96us	275us	271us