Hello! 
I really really need some help with interfacing two 4x4 keyboards.
I have stumbled upon this example and code of a 4x4 keyboard being charlieplexed. I really need to use two 4x4 keyboards for my project and this solution fits my needs perfectly since I would like to spare some pins on my arduino. Sadly I have a slight problem that I'm not sure how to solve. I have written in on the topic itself but there is no response (it's an old topic)...
I duplicated the code, renamed all the integers and the code generally works, but only if I use one or the other "half" of the code seperately - meaning I comment one or the other part of the code (one or the other keyboard).
My problem is that when I uncomment the code and join the two pieces together, the code does not read the keyboards at all.
I don't understand what is wrong, so if someone can shed any light on this it would be awesome! ..and probably usefull to others also...
Thanks for any insights!
#define RK1_0 B10000100
#define RK1_1 B00011000
#define RK1_2 B00011100
#define RK1_3 B00010110
#define RK1_4 B00101001
#define RK1_5 B00101100
#define RK1_6 B00100100
#define RK1_7 B01001001
#define RK1_8 B01001000
#define RK1_9 B01000010
#define RK1_NUM B10000110
#define RK1_STAR B10000001
#define RK1_A B00010010
#define RK1_B B00100001
#define RK1_C B01000011
#define RK1_D B10000011
#define RK2_0 B10000100
#define RK2_1 B00011000
#define RK2_2 B00011100
#define RK2_3 B00010110
#define RK2_4 B00101001
#define RK2_5 B00101100
#define RK2_6 B00100100
#define RK2_7 B01001001
#define RK2_8 B01001000
#define RK2_9 B01000010
#define RK2_NUM B10000110
#define RK2_STAR B10000001
#define RK2_A B00010010
#define RK2_B B00100001
#define RK2_C B01000011
#define RK2_D B10000011
const int PinKM1[] = {4, 5, 6, 7}; // four pins to Keyboard Matrix
const int PinKM2[] = {8, 9, 10, 11}; // four pins to Keyboard Matrix
void setup(void){
Serial.begin(9600);
}
void loop(void) {
char c1 = ReadKey1();
Serial.println(c1);
delay (10);
char c2 = ReadKey2();
Serial.println(c2);
delay (10);
}
// ------------------- ReadKey -------------------
// wait for a key to be pressed
char ReadKey1(void) {
char c1;
byte r1;
unsigned long ti = millis() + 2000; // simple autorepeat
while (0 != ReadKeyboardRaw1() && ti > millis()); // wait for previeus key to be unpressed..
do {
while (0 == (r1 = ReadKeyboardRaw1()));
delay(10);
}
while ( r1 != ReadKeyboardRaw1() );
switch (r1) {
case RK1_0: c1 = '0'; break;
case RK1_1: c1 = '1'; break;
case RK1_2: c1 = '2'; break;
case RK1_3: c1 = '3'; break;
case RK1_4: c1 = '4'; break;
case RK1_5: c1 = '5'; break;
case RK1_6: c1 = '6'; break;
case RK1_7: c1 = '7'; break;
case RK1_8: c1 = '8'; break;
case RK1_9: c1 = '9'; break;
case RK1_NUM: c1 = '#'; break;
case RK1_STAR: c1 = '*'; break;
case RK1_A: c1 = 'A'; break;
case RK1_B: c1 = 'B'; break;
case RK1_C: c1 = 'C'; break;
case RK1_D: c1 = 'D'; break;
default: c1 = '?';
}
return c1;
}
// ------------------- ReadKey -------------------
// wait for a key to be pressed
char ReadKey2(void) {
char c2;
byte r2;
unsigned long tm = millis() + 2000; // simple autorepeat
while (0 != ReadKeyboardRaw2() && tm > millis()); // wait for previeus key to be unpressed..
do {
while (0 == (r2 = ReadKeyboardRaw2()));
delay(10);
}
while (r2 != ReadKeyboardRaw2());
switch (r2) {
case RK2_0: c2 = '0'; break;
case RK2_1: c2 = '1'; break;
case RK2_2: c2 = '2'; break;
case RK2_3: c2 = '3'; break;
case RK2_4: c2 = '4'; break;
case RK2_5: c2 = '5'; break;
case RK2_6: c2 = '6'; break;
case RK2_7: c2 = '7'; break;
case RK2_8: c2 = '8'; break;
case RK2_9: c2 = '9'; break;
case RK2_NUM: c2 = '#'; break;
case RK2_STAR: c2 = '*'; break;
case RK2_A: c2 = 'A'; break;
case RK2_B: c2 = 'B'; break;
case RK2_C: c2 = 'C'; break;
case RK2_D: c2 = 'D'; break;
default: c2 = '?';
}
return c2;
}
// ------------------- ReadKeyboardRaw -------------------
byte ReadKeyboardRaw1(void) {
byte RawKey1 = 0;
for (byte i = 0; i < 4; i++) {
// setup ports..
for (byte j = 0; j < 4; j++) {
if (i == j) { // output '0'
pinMode(PinKM1[j], OUTPUT);
digitalWrite( PinKM1[j], LOW);
}
else { // input
pinMode(PinKM1[j], INPUT);
digitalWrite( PinKM1[j], HIGH);
}
}
delay(1);
// read ports..
for (byte j = 0; j < 4; j++) {
if (i != j) {
if (LOW == digitalRead(PinKM1[j])) {
bitSet(RawKey1, j);
}
}
}
if (RawKey1 != 0x0) { // key pressed, return key
bitSet(RawKey1, i + 4);
break; //return RawKey1;
}
}
// Serial.println(RawKey1);
return RawKey1;
}
// ------------------- ReadKeyboardRaw -------------------
byte ReadKeyboardRaw2(void) {
byte RawKey2 = 0;
for (byte k = 0; k < 4; k++) {
// setup ports..
for (byte l = 0; l < 4; l++) {
if (k == l) { // output '0'
pinMode(PinKM2[l], OUTPUT);
digitalWrite( PinKM2[l], LOW);
}
else { // input
pinMode(PinKM2[l], INPUT);
digitalWrite( PinKM2[l], HIGH);
}
}
delay(1);
// read ports..
for (byte l = 0; l < 4; l++) {
if (k != l) {
if (LOW == digitalRead(PinKM2[l])) {
bitSet(RawKey2, l);
}
}
}
if (RawKey2 != 0x0) { // key pressed, return key
bitSet(RawKey2, k + 4);
break; //return RawKey2;
}
}
// Serial.println(RawKey2);
return RawKey2;
}