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/*
* Copyright 2020 Daniel Friesel
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "driver/spi.h"
#include "driver/gpio.h"
#include "arch.h"
#include <avr/io.h>
signed char SPI::setup()
{
// configure SS as output to avoid unintened switches to slave mode
gpio.output(GPIO::pb2, 0);
// up to 1 MHz SPI clock
#if F_CPU == 16000000UL
SPCR = _BV(SPE) | _BV(MSTR) | _BV(SPR0);
#elif F_CPU == 8000000UL
SPCR = _BV(SPE) | _BV(MSTR) | _BV(SPR0);
#else
SPCR = _BV(SPE) | _BV(MSTR);
#endif
}
signed char SPI::xmit(
unsigned char tx_len, unsigned char *tx_buf,
unsigned char rx_len, unsigned char *rx_buf)
{
unsigned char i;
while ((i < tx_len) || (i < rx_len)) {
if (i < tx_len) {
SPDR = tx_buf[i];
} else {
SPDR = 0;
}
while (!(SPSR & _BV(SPIF))) ;
if (i < rx_len) {
rx_buf[i] = SPDR;
}
i++;
}
return 0;
}
SPI spi;
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