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180 lines
4.5 KiB
180 lines
4.5 KiB
/* Copyright 2020
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include "spi_master.h"
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#include "timer.h"
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#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__)
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# define SPI_SCK_PIN B1
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# define SPI_MOSI_PIN B2
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# define SPI_MISO_PIN B3
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#elif defined(__AVR_ATmega32A__)
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# define SPI_SCK_PIN B7
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# define SPI_MOSI_PIN B5
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# define SPI_MISO_PIN B6
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#elif defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)
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# define SPI_SCK_PIN B5
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# define SPI_MOSI_PIN B3
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# define SPI_MISO_PIN B4
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#endif
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#ifndef SPI_TIMEOUT
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# define SPI_TIMEOUT 100
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#endif
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static pin_t currentSlavePin = NO_PIN;
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static uint8_t currentSlaveConfig = 0;
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static bool currentSlave2X = false;
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void spi_init(void) {
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writePinHigh(SPI_SS_PIN);
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setPinOutput(SPI_SCK_PIN);
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setPinOutput(SPI_MOSI_PIN);
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setPinInput(SPI_MISO_PIN);
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SPCR = (_BV(SPE) | _BV(MSTR));
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}
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bool spi_start(pin_t slavePin, bool lsbFirst, uint8_t mode, uint16_t divisor) {
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if (currentSlavePin != NO_PIN || slavePin == NO_PIN) {
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return false;
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}
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currentSlaveConfig = 0;
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if (lsbFirst) {
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currentSlaveConfig |= _BV(DORD);
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}
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switch (mode) {
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case 1:
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currentSlaveConfig |= _BV(CPHA);
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break;
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case 2:
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currentSlaveConfig |= _BV(CPOL);
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break;
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case 3:
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currentSlaveConfig |= (_BV(CPOL) | _BV(CPHA));
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break;
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}
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uint16_t roundedDivisor = 1;
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while (roundedDivisor < divisor) {
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roundedDivisor <<= 1;
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}
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switch (roundedDivisor) {
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case 16:
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currentSlaveConfig |= _BV(SPR0);
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break;
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case 64:
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currentSlaveConfig |= _BV(SPR1);
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break;
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case 128:
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currentSlaveConfig |= (_BV(SPR1) | _BV(SPR0));
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break;
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case 2:
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currentSlave2X = true;
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break;
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case 8:
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currentSlave2X = true;
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currentSlaveConfig |= _BV(SPR0);
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break;
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case 32:
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currentSlave2X = true;
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currentSlaveConfig |= _BV(SPR1);
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break;
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}
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SPCR |= currentSlaveConfig;
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if (currentSlave2X) {
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SPSR |= _BV(SPI2X);
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}
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currentSlavePin = slavePin;
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setPinOutput(currentSlavePin);
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writePinLow(currentSlavePin);
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return true;
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}
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spi_status_t spi_write(uint8_t data) {
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SPDR = data;
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uint16_t timeout_timer = timer_read();
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while (!(SPSR & _BV(SPIF))) {
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if ((timer_read() - timeout_timer) >= SPI_TIMEOUT) {
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return SPI_STATUS_TIMEOUT;
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}
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}
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return SPDR;
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}
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spi_status_t spi_read() {
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SPDR = 0x00; // Dummy
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uint16_t timeout_timer = timer_read();
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while (!(SPSR & _BV(SPIF))) {
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if ((timer_read() - timeout_timer) >= SPI_TIMEOUT) {
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return SPI_STATUS_TIMEOUT;
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}
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}
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return SPDR;
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}
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spi_status_t spi_transmit(const uint8_t *data, uint16_t length) {
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spi_status_t status;
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for (uint16_t i = 0; i < length; i++) {
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status = spi_write(data[i]);
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if (status < 0) {
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return status;
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}
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}
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return SPI_STATUS_SUCCESS;
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}
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spi_status_t spi_receive(uint8_t *data, uint16_t length) {
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spi_status_t status;
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for (uint16_t i = 0; i < length; i++) {
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status = spi_read();
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if (status >= 0) {
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data[i] = status;
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} else {
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return status;
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}
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}
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return SPI_STATUS_SUCCESS;
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}
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void spi_stop(void) {
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if (currentSlavePin != NO_PIN) {
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setPinOutput(currentSlavePin);
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writePinHigh(currentSlavePin);
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currentSlavePin = NO_PIN;
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SPSR &= ~(_BV(SPI2X));
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SPCR &= ~(currentSlaveConfig);
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currentSlaveConfig = 0;
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currentSlave2X = false;
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}
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}
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