spi.c

/*
 * GccApplication1.c
 *
 * Created: 19.11.2013 13:22:54
 *  Author: ese1-30
 */ 


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

#define DDR_SPI DDRB
#define PORT_SPI PORTB
#define DD_MOSI DDB2
#define DD_SCK DDB1
#define DD_SS DDB0

void SPI_MasterInit()
{
	DDR_SPI = (1 << DD_MOSI) | (1 << DD_SCK) | (1 << DD_SS);
	PORT_SPI = 0b1;

	SPCR = (1 << SPE) | (1 << MSTR) | (1<<SPR0);
}

void SPI_MasterTransmit(char ch)
{
	PORT_SPI = 0b0;
	
	SPDR = ch;
	
	while(!(SPSR & (1<<SPIF)));
	
	PORT_SPI = 0b1;
}

void SPI_MasterTransmitString(char *str)
{
	while (*str) {
		SPI_MasterTransmit(*str);
		str++;
	}
}

char read_key() {
	uint8_t key;
	
	PORTA = 0b11111101;
	_delay_us(10);
	key = (PINA >> 4) & (0b00001111);
	switch (key) {
		case 0x07:
			return '3';
		case 0x0B:
			return '6';
		case 0x0D:
			return '9';
		case 0x0E:
			return 'E';
	}
	
	PORTA = 0b11111110;
	_delay_us(10);
	key = (PINA >> 4) & (0b00001111);
	switch (key) {
		case 0x07:
			return 'A';
		case 0x0B:
			return 'B';
		case 0x0D:
			return 'C';
		case 0x0E:
			return 'D';
	}
	
	PORTA = 0b11111011;
	_delay_us(10);
	key = (PINA >> 4) & (0b00001111);
	switch (key) {
		case 0x07:
			return '2';
		case 0x0B:
			return '5';
		case 0x0D:
			return '8';
		case 0x0E:
			return 'F';
	}
	
	PORTA = 0b11110111;
	_delay_us(10);
	key = (PINA >> 4) & (0b00001111);
	switch (key) {
		case 0x07:
			return '1';
		case 0x0B:
			return '4';
		case 0x0D:
			return '7';
		case 0x0E:
			return '0';
	}
	
	return 0;
}

int main(void)
{
	// Init keyboard.
	DDRA = 0b00001111;
	
	SPI_MasterInit();
	
	SPI_MasterTransmitString("\e[j");
	
	char previous = 0;
	
	int len = 0;
	
	while (1) {
		char key = read_key();
		if (key && key != previous) {
			if (len == 16) {
				SPI_MasterTransmitString("\e[1;0H");
			} else if (len == 32) {
				SPI_MasterTransmitString("\e[j");
				len = 0;
			}
			SPI_MasterTransmit(key);
			len++;
		}
		previous = key;	
	}
}