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/*
** Copyright (C) 2009 Onno Kortmann <onno@gmx.net>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License along
** with this program; if not, write to the Free Software Foundation, Inc.,
** 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA..
**
*/
#include <avr/io.h>
#define SPI_CS 2
#define SPI_MOSI 3
#define SPI_MISO 4
#define SPI_SCK 5
void spitxdel() {
while(!(SPSR & (1<<SPIF))); SPDR;
// 'slave reset'
PORTB |= _BV(SPI_CS);
PORTB &= ~_BV(SPI_CS);
}
int main() {
DDRB |= (1<<SPI_CS);
DDRB |= (1<<SPI_MOSI);
DDRB &=~(1<<SPI_MISO);
DDRB |= (1<<SPI_SCK);
// 'slave reset'
PORTB |= _BV(SPI_CS);
PORTB &= ~_BV(SPI_CS);
// standard options
SPCR = (1<<SPE)|(1<<MSTR)|(1<<DORD);
SPDR = 0xa5;
spitxdel();
// two times rate
SPSR |= (1<<SPI2X);
SPDR = 0xa5;
spitxdel();
// MSB first
SPCR = (1<<SPE)|(1<<MSTR);
SPDR = 0xa5;
spitxdel();
// inversed clock
SPCR = (1<<SPE)|(1<<MSTR)|(1<<CPOL);
SPDR = 0xa5;
spitxdel();
// other phase
SPCR = (1<<SPE)|(1<<MSTR)|(1<<CPHA);
SPDR = 0xa5;
spitxdel();
}
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