I bought a module from ebay, it has 8 LED digits and 16 buttons. The display is common anode so the standard TM1638 library wouldn’t work properly without some extra coding. Basically the digit are driven by what is normally the segment outputs and the segments are driven by what is normally the digit outputs. Also the buttons require more bits because there are 16 of them.
Link to ebay for similar item:
To get the buttons to work I needed to add a function to the library (need to add a line to the header file also), the library should be under the Arduino folder in a library folder in the file system.
Here is what I came up with to test the module:
The library I used:
Add the following code to the TM1638.cpp library file (needed to read buttons)
uint16_t TM1638::getButtons16()
{
byte keys[4] = {0,0,0,0};
uint16_t valueButtons;
digitalWrite(strobePin, LOW);
send(0x42);
for (int i = 0; i < 4; i++) {
keys[i] = receive();
keys[i] = keys[i] >> 1; // pack key value into lower nibble
if (keys[i] > 2) {
keys[i] = keys[i] >> 2;
}
}
digitalWrite(strobePin, HIGH);
valueButtons = (keys[3] << 12) | (keys[2] << 8) | (keys[1] << 4) | keys[0]; // Pack nibbles into return integer
return valueButtons;
}
Add the following line to TM1638.h under the public section (needed to read buttons)
virtual uint16_t getButtons16();
// Arduino code to test the 8 LED common anode module with 16 keys
/*
Example for TM1638 with an 8 digit common anode display.
The module also contains 16 buttons
The button value is returned in an unsigned integer with each bit representing a button
The keys are in a 4x4 grid (returned value):
2 8 32 128
512 2048 8192 32768
1 4 16 64
256 1024 4096 16384
*/
#include <TM1638.h>
// define a module on data pin 8, clock pin 9 and strobe pin 7
TM1638 module(8, 9, 7);
// declare variables / constants
const byte segmentEncode[10] = {63, 6, 91, 79, 102, 109, 125, 7, 127, 111}; // for digits from 0 to 9
uint16_t keys; // to hold key value - each key is 1 bit in this unsigned int
void setup() {
// set up serial monitor
Serial.begin(9600);
}
// Function to format and send digits to the display module, fixed to send to 8 digit display currently
void outputDisplay(byte dDigits[8], byte dDecimal) {
byte values[8];
byte vout[8];
// set values array to the segments required for each displayed digit into values array, only for decimal 0-9 (could extend for HEX)
for (int i=0; i < 8; i++) {
values[i] = segmentEncode[dDigits[i]];
}
// fill output array - need to pack for common anode display - brute force method, this is for 8 digits
// digit order on display from left to right is 4,3,2,1,8,7,6,5
vout[0] = (values[3] & 1) | ((values[2] & 1) << 1) | ((values[1] & 1) << 2) | ((values[0] & 1) << 3) | ((values[7] & 1) << 4) | ((values[6] & 1) << 5) | ((values[5] & 1) << 6) | ((values[4] & 1) << 7);
vout[1] = ((values[3] & 2) >> 1) | ((values[2] & 2)) | ((values[1] & 2) << 1) | ((values[0] & 2) << 2) | ((values[7] & 2) << 3) | ((values[6] & 2) << 4) | ((values[5] & 2) << 5) | ((values[4] & 2) << 6);
vout[2] = ((values[3] & 4) >> 2) | ((values[2] & 4) >> 1) | ((values[1] & 4)) | ((values[0] & 4) << 1) | ((values[7] & 4) << 2) | ((values[6] & 4) << 3) | ((values[5] & 4) << 4) | ((values[4] & 4) << 5);
vout[3] = ((values[3] & 8) >> 3) | ((values[2] & 8) >> 2) | ((values[1] & 8) >> 1) | ((values[0] & 8)) | ((values[7] & 8) << 1) | ((values[6] & 8) << 2) | ((values[5] & 8) << 3) | ((values[4] & 8) << 4);
vout[4] = ((values[3] & 16) >> 4) | ((values[2] & 16) >> 3) | ((values[1] & 16) >> 2) | ((values[0] & 16) >> 1) | ((values[7] & 16)) | ((values[6] & 16) << 1) | ((values[5] & 16) << 2) | ((values[4] & 16) << 3);
vout[5] = ((values[3] & 32) >> 5) | ((values[2] & 32) >> 4) | ((values[1] & 32) >> 3) | ((values[0] & 32) >> 2) | ((values[7] & 32) >> 1) | ((values[6] & 32)) | ((values[5] & 32) << 1) | ((values[4] & 32) << 2);
vout[6] = ((values[3] & 64) >> 6) | ((values[2] & 64) >> 5) | ((values[1] & 64) >> 4) | ((values[0] & 64) >> 3) | ((values[7] & 64) >> 2) | ((values[6] & 64) >> 1) | ((values[5] & 64)) | ((values[4] & 64) << 1);
// To display a decimal point to the right of a digit set the value of vout[7] to
// 8, 4, 2, 1, 128, 64, 32, 16 (for digits from left to right), can set more than 1 decimal by adding the numbers
vout[7] = dDecimal;
module.setDisplay(vout); // send to display module
} // end outputDisplay
void loop() {
keys = module.getButtons16(); // get a key (button)
// output key value to serial monitor
if (keys) {
Serial.println(keys);
}
// Digits to output on 8 display digits
byte displayDigits[8] = {0, 1, 2, 3, 4, 5, 6, 7};
// The second parameter is the decimal point - set 1 bit for each decimal displayed
outputDisplay(displayDigits, 8);
delay(200); // delay .2 seconds then loop
}
