gistfile1.c

/* Name: main.c
 * Author: Quinn Dunki
 * Copyright: ©2012 Quinn Dunki
 * License: All Rights Reserved
 *
 * ATtiny13A code to program an SRAM chip or EEPROM
 * For details, see http://www.quinndunki.com/blondihacks
 */


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

#define QDDRB(n) (1<<(DDB##n))
#define QPINBIT(n) PB##n
#define SET_HI(pin) PORTB |= (1<<(QPINBIT(pin)))
#define SET_LO(pin) PORTB &= ~(1<<(QPINBIT(pin)))
#define PULSE(pin) SET_HI(pin); SET_LO(pin);
#define LOPULSE(pin) SET_LO(pin); SET_HI(pin);

#define SER_ADDR 0    	// Serial data to Address registers
#define SER_DATA 1		// Serial data to Data register
#define ROM_CLK 2		// Shift & Latch clocks for shift registers
#define BYTE_WRITE 3	// Chip Enable strobe on EEPROM
#define LEDS 4			// Status LEDs (HI=red, LO=green)

#define BASE_ADDRESS 0xf000		// Address at which to load the ROM image
#define ROM_SIZE 4096
#define EEPROM_PAGE_SIZE 64
#define EEPROM_PAGE_MASK 0xffc0

// Invoke our ROM image here, so the code can reference it
#include "rom.c"


// Main loop
int main(void)
{
	_delay_ms(15);	// Give the EEPROM time to wake up

	// Configure all pins as outputs
	DDRB = QDDRB(0) | QDDRB(1) | QDDRB(2) | QDDRB(3) | QDDRB(4);
	
	// Initialize some states
	SET_LO(ROM_CLK);
	SET_HI(BYTE_WRITE);
	SET_HI(LEDS);
	
	uint16_t byte = 0;
	uint16_t address = BASE_ADDRESS;
	uint16_t data = 0;
	uint16_t pageByte = 0;
	uint16_t pageNum = address & EEPROM_PAGE_MASK;
	int bit=0;
		
	// Iterate every byte in the ROM image
	for (; byte<ROM_SIZE; byte++)
	{
		// Calculate the effective address and desired byte from the image
		uint8_t db = pgm_read_byte(&romData[byte]);
		data = (db<<8) | db;	// Double-up the data byte, because it will be shifted out twice
		
		// Push the data and address out to the registers. Note one extra loop
		// to compensate for shift and latch clocks being tied together
		uint16_t mask = 1<<15;
		for (bit=0; bit<17; bit++)
		{
			if (address & mask)
			{
				SET_HI(SER_ADDR);
			}
			else
			{
				SET_LO(SER_ADDR);
			}
			
			if (data & mask)
			{
				SET_HI(SER_DATA);
			}
			else
			{
				SET_LO(SER_DATA);
			}
		
			mask >>= 1;
			PULSE(ROM_CLK);
		}

		LOPULSE(BYTE_WRITE);

		// After each EEPROM page, wait for the write to complete
		address++;
		uint16_t nextPageNum = address & EEPROM_PAGE_MASK;
		
		pageByte++;
		if (pageByte >= EEPROM_PAGE_SIZE || pageNum != nextPageNum)
		{
			pageByte = 0;
			pageNum = nextPageNum;
			_delay_ms(8);
		}		
	}
	
	// We're done, so give the green light
	SET_LO(LEDS);

    return 0;
}