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/* USRP E310 Firmware Atmel AVR SPI driver
* Copyright (C) 2014 Ettus Research
* This file is part of the USRP E310 Firmware
* The USRP E310 Firmware 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.
* The USRP E310 Firmware 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 the USRP E310 Firmware. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mcu_settings.h"
#include "io.h"
#include "spi.h"
#include "utils.h"
#include <avr/io.h>
#include <stdlib.h>
#include <util/delay.h>
static io_pin_t AVR_CS = IO_PB(2);
static io_pin_t AVR_MOSI = IO_PB(3);
static io_pin_t AVR_MISO = IO_PB(4);
static io_pin_t AVR_SCK = IO_PB(5);
void spi_init(spi_type_t type, spi_order_t order, spi_mode_t mode, spi_speed_t speed)
{
uint8_t val;
io_output_pin(AVR_CS);
io_output_pin(AVR_MOSI);
io_input_pin(AVR_MISO);
io_output_pin(AVR_SCK);
/* slave select is low active */
io_set_pin(AVR_CS);
/* SPCR looks like this: [SPIE | SPE | DORD | MSTR | CPOL | CPHA | SPR1 | SPR0] */
val = BIT(SPE);
val |= (order == SPI_LSB_FIRST) ? BIT(DORD) : 0;
val |= (type == SPI_TYPE_MASTER) ? BIT(MSTR) : 0;
val |= mode << CPHA;
val |= speed << SPR0;
SPCR = val;
}
uint8_t spi_transact(uint8_t data)
{
uint8_t ret;
io_clear_pin(AVR_CS);
SPDR = data;
ret = SPDR;
io_set_pin(AVR_CS);
return ret;
}
void spi_transact_buf(uint8_t *in, uint8_t *out, uint8_t size)
{
uint8_t i;
io_clear_pin(AVR_CS);
for (i = 0; i < size; i++) {
SPDR = in[i];
spi_wait_till_done();
out[i] = SPDR;
}
io_set_pin(AVR_CS);
}
void spi_wait_till_done(void)
{
uint8_t timeout = 100;
do {
_delay_us(10);
timeout--;
} while (timeout && !(SPSR & BIT(SPIF)));
}
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