/*
 * ATMEGA328_clockgen.c
 *
 * Created: 02.01.2022 02:58:26
 * Author : tboes
 
 Generate clock on PB0 / D8
 */ 

#include <avr/io.h>
#include <util/delay.h>

void resetstring(void);
void sendpulse(void);
void sendcmd(uint8_t address, uint8_t cmd);

int main(void)
{
	DDRB |= _BV(PB0);
	
	resetstring();

    while (1) 
    {
		sendcmd(1,0);
		sendcmd(2,0);
		sendcmd(3,0);
		sendcmd(4,0);
		sendcmd(5,0);
		sendcmd(6,0);

		_delay_ms(5);
		sendcmd(1,1); // 10
		sendcmd(2,2); // 4
		sendcmd(3,4); // 1
		sendcmd(4,1);  // 7
		sendcmd(5,2); // 2, 8,9
		sendcmd(6,4); // 3,5,6
//		_delay_ms(5);
//		sendcmd(8,2);
		_delay_ms(20);
    }
}


#define basetime_us 8
#define frameidle_us basetime_us*5  // cover worst case where data field is zero 
									
void sendcmd(uint8_t address, uint8_t cmd) {
	
	for (uint8_t i=0; i<address+1; i++) {
		sendpulse();
	}
	
	_delay_us((basetime_us*3)/2);
		
	for (uint8_t i=0; i<cmd+1; i++) {
		sendpulse();
	}
	_delay_us(frameidle_us);
}

// Send pulse of 31.25µs low, 31.25µs high
void sendpulse(void) {
		PORTB &= ~_BV(PB0);
		_delay_us(basetime_us);
		PORTB |= _BV(PB0);
		_delay_us(basetime_us);	
}

void resetstring(void) {
		PORTB &= ~_BV(PB0);
		_delay_ms(3.28);
		PORTB |= _BV(PB0);
		_delay_us(280);
		
		for (uint8_t i=0; i<36; i++) {  // original controller uses 36 cycles, but fewer also seem to be ok
			PORTB &= ~_BV(PB0);
			_delay_us(135);
			PORTB |= _BV(PB0);
			_delay_us(135);			
		}
		
		_delay_us(540);
		// turn everything off twice. Some LEDs indeed seem to react only to second cycle. Not sure whether there is a systematic reason
		
		for (uint8_t i=1; i<8; i++) {
			sendcmd(i,0);
		}

		for (uint8_t i=1; i<7; i++) {
			sendcmd(i,0);
		}

}