spi.c

来自「avr+TFT+SD卡实现数码相框功能」· C语言 代码 · 共 60 行

//*****************************************************************************
//
// File Name	: 'spi.c'
// Title		: SPI interface driver
// Author		: Andy Zhu
// Created		: 07/20/2008
// Revised		: 07/20/2008
// Version		: 0.1
// Target MCU	: Atmel AVR ATmega128
//
//*****************************************************************************

#include <avr/io.h>
//#include <avr/signal.h>
//#include <avr/interrupt.h>

#include "spi.h"

// access routines
void SPI_init(void)
{
	/* 设置MOSI和SCK及SS为输出，其他为输入 */
	PORTB |= (1<<MOSI)|(1<<SCK);
	
	/* 使能SPI,主机模式，设置时钟速率为Fosc/2 */
	SPCR = (1<<SPE)|(1<<MSTR);
	SPSR |= (1<<SPI2X);	//SPI倍速
}

void spiSendByte(unsigned char spi_data)
{
	/* 启动数据传输 */
	SPDR = spi_data;
	/* 等待传输结束 */
	while(!(SPSR & (1<<SPIF)))
		;
}

unsigned char spiTransferByte(unsigned char out_data)
{
	/* 启动数据传输 */
	SPDR = out_data;
	/* 等待传输结束 */
	while(!(SPSR & (1<<SPIF)));
	return SPDR;
}

unsigned int spiTransferWord(unsigned int data)
{
	unsigned int rxData = 0;

	// send MS byte of given data
	rxData = (spiTransferByte((data>>8) & 0x00FF))<<8;
	// send LS byte of given data
	rxData |= (spiTransferByte(data & 0x00FF));

	// return the received data
	return rxData;
}