Huge nested loop in Arduino

Question

I am completely new to programming and I am trying a brute force programming on my garage door opener. I want to use an Arduino for learning purposes. I wrote the following program that finally did what it should and now I am wondering whether there is a shorter code that does the same. Is anyone able to help me in that matter?

I do know that about 2^12 possibilities existed so I ran through all of them. I also knew that some parts of the "pulsetrain" (the set of necessary pulses) start with a particular sequence that is always the same (for all "brute forced" trains) and that the closing sequence is also always identical. I then simply wrote that down in the following, nasty code:

/*
 Transmitter is connected to Arduino Pin #2
*/
void setup() {
 pinMode(2, OUTPUT);
}
void pulsetrain(int a, int b, int c, int d, int e, int f, int g, int h, int i, int j, int k, int l, int m) {
 PORTD &= ~_BV(PD2);
 //set to LOW, hardwired to make it faster, see http://www.instructables.com/id/Arduino-is-Slow-and-how-to-fix-it/?ALLSTEPS
 delayMicroseconds(283); // (D2)
 PORTD |= _BV(PD2); //set to HIGH
 delayMicroseconds(566);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(283);
 PORTD |= _BV(PD2);
 delayMicroseconds(566);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(a);
 PORTD |= _BV(PD2);
 delayMicroseconds(b);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(c);
 PORTD |= _BV(PD2);
 delayMicroseconds(d);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(e);
 PORTD |= _BV(PD2);
 delayMicroseconds(f);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(g);
 PORTD |= _BV(PD2);
 delayMicroseconds(h);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(i);
 PORTD |= _BV(PD2);
 delayMicroseconds(j);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(k);
 PORTD |= _BV(PD2);
 delayMicroseconds(l);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(m);
 PORTD |= _BV(PD2);
 delayMicroseconds(283);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(566);
 PORTD |= _BV(PD2);
 delayMicroseconds(283);
 PORTD &= ~_BV(PD2);
 delayMicroseconds(566);
 PORTD &= ~_BV(PD2); // last LOW
}
void loop() {
 int signals[2] = {283, 566};
 for (int a = 0; a < 2; a++) {
 for (int b = 0; b < 2; b++) {
 for (int c = 0; c < 2; c++) {
 for (int d = 0; d < 2; d++) {
 for (int e = 0; e < 2; e++) {
 for (int f = 0; f < 2; f++) {
 for (int g = 0; g < 2; g++) {
 for (int h = 0; h < 2; h++) {
 for (int i = 0; i < 2; i++) {
 for (int j = 0; j < 2; j++) {
 for (int k = 0; k < 2; k++) {
 for (int l = 0; l < 2; l++) {
 for (int m = 0; m < 2; m++) {
 pulsetrain(signals[a], signals[b], signals[c], signals[d], signals[e], signals[f], signals[g], signals[h], signals[i], signals[j], signals[k], signals[l], signals[m]);
 }
 }
 }
 }
 }
 }
 }
 }
 }
 }
 }
 }
 }
}

• Gerben: Just look at at like 283 is a low bit, and 566 is a high bit. So a-m would become a 13 bit number. Loop through those numbers with a for loop (0-8191). Then in the pulsetrain function read one bit, apply the delay of 283 or 566 based on the bit being 0 or 1. Then shift all the bit (left or right), and repeat (13 times).
• Andreas: My problem is not that I cannot program the opener (the above code did what it should) and I also understand the Manchester Coding. I wanted a code that does the same but consists of less than the above 84 lines! I do not know how to handle binary() and DecimalToBinary() (if it is even defined) with an arduino.

Answer 1

All those variables a, b, etc. are just the individual bits of a 13-bit number. When you loop through all combinations, you are actually looping through all the possible numeric values of a 13-bit number. This can be simplified as this (warning: not tested):

void setup() {
 pinMode(2, OUTPUT);
}
// the bitstream is: 0.101x xxxx.xxxx xxxx.0101
void pulsetrain(uint16_t code) {
 uint32_t bitstream = (((uint32_t) code) << 4) | 0x0a0005UL;
 for (uint8_t i = 0; i < 21; i++) {
 PIND = _BV(PD2); // toggle pin
 if (bitstream & 0x100000)
 delayMicroseconds(566);
 else
 delayMicroseconds(283);
 bitstream <<= 1;
 }
 PORTD &= ~_BV(PD2); // last LOW
}
void loop() {
 for (uint16_t code = 0; code < 0x2000; code++) {
 pulsetrain(code);
 }
}