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keypad_4x4_i2c_nano_backpack.ino
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keypad_4x4_i2c_nano_backpack.ino
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#include <Wire.h>
/**
*
* This is a derivative of the Keypad 3x4 I2C Nano Backpack.
* Much of the code is the same, however due to an additional 8th pin, some of
* the code has to be modified to suit 16 buttons instead of 12.
*
*/
#define DEBUG_MODE 0
// Address Pins
#define AD0 11
#define AD1 12
// I2C Defaults
#define I2C_DEFAULT_ADDRESS 0x0A
#define I2C_BUFFER_SIZE 2
byte buffer[I2C_BUFFER_SIZE];
int addressPins[] = { AD0, AD1 };
int address = I2C_DEFAULT_ADDRESS;
int pins[8] = {8, 7, 6, 5, 4, 3, 2, 9};
void resetPins() {
for (int i = 0; i < 8; i++) {
pinMode(pins[i], INPUT);
digitalWrite(pins[i], HIGH);
}
}
void setup() {
int offset = 0;
for (int i = 0; i < 2; i++) {
pinMode(addressPins[i], INPUT);
if (digitalRead(addressPins[i])) {
offset |= 1 << i;
}
}
address += offset;
#if DEBUG_MODE
Serial.begin(9600);
#endif
resetPins();
Wire.begin(address);
Wire.onRequest(onRequest);
}
void loop() {
int state = read();
// int index = toIndex(state);
// if (state == 0) {
// index = 0xFF;
// }
// #if DEBUG_MODE
// if (index != 0xff) {
// Serial.println(index);
// }
// #endif
// buffer[0] = index >> 8;
// buffer[1] = index & 0xFF;
buffer[0] = state >> 8;
buffer[1] = state & 0xFF;
delay(10);
}
int toIndex(int bits) {
for (int i = 0; i < 16; i++) {
if (bits & (1 << i)) {
return i;
}
}
}
int read() {
// 2, 7, 6, 4
// 3, 1, 5, 9
int rowPins[4] = {7, 2, 3, 5};
int colPins[4] = {6, 8, 4, 9};
int state = 0;
resetPins();
for (int row = 0; row < 4; row++) {
// "Open" the row for reading...
// Set the row to OUTPUT and put all pins LOW
pinMode(rowPins[row], OUTPUT);
digitalWrite(rowPins[row], LOW);
// Iterate across the columns in this row
for (int col = 0; col < 4; col++) {
// Read and update the state byte
if (!digitalRead(colPins[col])) {
state |= 1 << ((row + 1) * 4 + (col + 1) - 5);
}
}
// "Close" the row...
// Set the row to INPUT and put all pins HIGH
pinMode(rowPins[row], INPUT);
digitalWrite(rowPins[row], HIGH);
}
return state;
}
void onRequest() {
Wire.write(buffer, 2);
}