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/* Copyright 2020
*
* 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 3 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, see <https://www.gnu.org/licenses/>.
*/
#include "spi_master.h"
#include "timer.h"
#if defined(__AVR_AT90USB162__) || defined(__AVR_ATmega16U2__) || defined(__AVR_ATmega32U2__) || defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__) || defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
# define SPI_SCK_PIN B1
# define SPI_MOSI_PIN B2
# define SPI_MISO_PIN B3
#elif defined(__AVR_ATmega32A__)
# define SPI_SCK_PIN B7
# define SPI_MOSI_PIN B5
# define SPI_MISO_PIN B6
#elif defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)
# define SPI_SCK_PIN B5
# define SPI_MOSI_PIN B3
# define SPI_MISO_PIN B4
#endif
#ifndef SPI_TIMEOUT
# define SPI_TIMEOUT 100
#endif
static pin_t currentSlavePin = NO_PIN;
static uint8_t currentSlaveConfig = 0;
static bool currentSlave2X = false;
void spi_init(void) {
writePinHigh(SPI_SS_PIN);
setPinOutput(SPI_SCK_PIN);
setPinOutput(SPI_MOSI_PIN);
setPinInput(SPI_MISO_PIN);
SPCR = (_BV(SPE) | _BV(MSTR));
}
bool spi_start(pin_t slavePin, bool lsbFirst, uint8_t mode, uint16_t divisor) {
if (currentSlavePin != NO_PIN || slavePin == NO_PIN) {
return false;
}
currentSlaveConfig = 0;
if (lsbFirst) {
currentSlaveConfig |= _BV(DORD);
}
switch (mode) {
case 1:
currentSlaveConfig |= _BV(CPHA);
break;
case 2:
currentSlaveConfig |= _BV(CPOL);
break;
case 3:
currentSlaveConfig |= (_BV(CPOL) | _BV(CPHA));
break;
}
uint16_t roundedDivisor = 1;
while (roundedDivisor < divisor) {
roundedDivisor <<= 1;
}
switch (roundedDivisor) {
case 16:
currentSlaveConfig |= _BV(SPR0);
break;
case 64:
currentSlaveConfig |= _BV(SPR1);
break;
case 128:
currentSlaveConfig |= (_BV(SPR1) | _BV(SPR0));
break;
case 2:
currentSlave2X = true;
break;
case 8:
currentSlave2X = true;
currentSlaveConfig |= _BV(SPR0);
break;
case 32:
currentSlave2X = true;
currentSlaveConfig |= _BV(SPR1);
break;
}
SPCR |= currentSlaveConfig;
if (currentSlave2X) {
SPSR |= _BV(SPI2X);
}
currentSlavePin = slavePin;
setPinOutput(currentSlavePin);
writePinLow(currentSlavePin);
return true;
}
spi_status_t spi_write(uint8_t data) {
SPDR = data;
uint16_t timeout_timer = timer_read();
while (!(SPSR & _BV(SPIF))) {
if ((timer_read() - timeout_timer) >= SPI_TIMEOUT) {
return SPI_STATUS_TIMEOUT;
}
}
return SPDR;
}
spi_status_t spi_read() {
SPDR = 0x00; // Dummy
uint16_t timeout_timer = timer_read();
while (!(SPSR & _BV(SPIF))) {
if ((timer_read() - timeout_timer) >= SPI_TIMEOUT) {
return SPI_STATUS_TIMEOUT;
}
}
return SPDR;
}
spi_status_t spi_transmit(const uint8_t *data, uint16_t length) {
spi_status_t status;
for (uint16_t i = 0; i < length; i++) {
status = spi_write(data[i]);
if (status < 0) {
return status;
}
}
return SPI_STATUS_SUCCESS;
}
spi_status_t spi_receive(uint8_t *data, uint16_t length) {
spi_status_t status;
for (uint16_t i = 0; i < length; i++) {
status = spi_read();
if (status >= 0) {
data[i] = status;
} else {
return status;
}
}
return SPI_STATUS_SUCCESS;
}
void spi_stop(void) {
if (currentSlavePin != NO_PIN) {
setPinOutput(currentSlavePin);
writePinHigh(currentSlavePin);
currentSlavePin = NO_PIN;
SPSR &= ~(_BV(SPI2X));
SPCR &= ~(currentSlaveConfig);
currentSlaveConfig = 0;
currentSlave2X = false;
}
}
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