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109 lines
3.8 KiB
109 lines
3.8 KiB
/*
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Copyright 2018 Massdrop Inc.
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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 2 of the License, or
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(at your option) any later version.
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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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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "arm_atsam_protocol.h"
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#include "spi_master.h"
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#include "gpio.h"
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/* Determine bits to set for mux selection */
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#if SPI_DATAOUT_PIN % 2 == 0
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# define SPI_DATAOUT_MUX_SEL PMUXE
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#else
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# define SPI_DATAOUT_MUX_SEL PMUXO
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#endif
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/* Determine bits to set for mux selection */
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#if SPI_SCLK_PIN % 2 == 0
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# define SPI_SCLK_MUX_SEL PMUXE
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#else
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# define SPI_SCLK_MUX_SEL PMUXO
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#endif
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static pin_t currentSelectPin = NO_PIN;
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__attribute__((weak)) void spi_init(void) {
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static bool is_initialised = false;
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if (!is_initialised) {
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is_initialised = true;
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DBGC(DC_SPI_INIT_BEGIN);
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CLK_set_spi_freq(CHAN_SERCOM_SPI, FREQ_SPI_DEFAULT);
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// Set up MCU SPI pins
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PORT->Group[SAMD_PORT(SPI_DATAOUT_PIN)].PMUX[SAMD_PIN(SPI_DATAOUT_PIN) / 2].bit.SPI_DATAOUT_MUX_SEL = SPI_DATAOUT_MUX; // MUX select for sercom
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PORT->Group[SAMD_PORT(SPI_SCLK_PIN)].PMUX[SAMD_PIN(SPI_SCLK_PIN) / 2].bit.SPI_SCLK_MUX_SEL = SPI_SCLK_MUX; // MUX select for sercom
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PORT->Group[SAMD_PORT(SPI_DATAOUT_PIN)].PINCFG[SAMD_PIN(SPI_DATAOUT_PIN)].bit.PMUXEN = 1; // MUX Enable
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PORT->Group[SAMD_PORT(SPI_SCLK_PIN)].PINCFG[SAMD_PIN(SPI_SCLK_PIN)].bit.PMUXEN = 1; // MUX Enable
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DBGC(DC_SPI_INIT_COMPLETE);
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}
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}
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bool spi_start(pin_t csPin, bool lsbFirst, uint8_t mode, uint16_t divisor) {
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if (currentSelectPin != NO_PIN || csPin == NO_PIN) {
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return false;
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}
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currentSelectPin = csPin;
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gpio_set_pin_output(currentSelectPin);
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gpio_write_pin_low(currentSelectPin);
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SPI_SERCOM->SPI.CTRLA.bit.DORD = lsbFirst; // Data Order - LSB is transferred first
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SPI_SERCOM->SPI.CTRLA.bit.CPOL = 1; // Clock Polarity - SCK high when idle. Leading edge of cycle is falling. Trailing rising.
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SPI_SERCOM->SPI.CTRLA.bit.CPHA = 1; // Clock Phase - Leading Edge Falling, change, Trailing Edge - Rising, sample
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SPI_SERCOM->SPI.CTRLA.bit.DIPO = 3; // Data In Pinout - SERCOM PAD[3] is used as data input (Configure away from DOPO. Not using input.)
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SPI_SERCOM->SPI.CTRLA.bit.DOPO = 0; // Data Output PAD[0], Serial Clock PAD[1]
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SPI_SERCOM->SPI.CTRLA.bit.MODE = 3; // Operating Mode - Master operation
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SPI_SERCOM->SPI.CTRLA.bit.ENABLE = 1; // Enable - Peripheral is enabled or being enabled
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while (SPI_SERCOM->SPI.SYNCBUSY.bit.ENABLE) {
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DBGC(DC_SPI_SYNC_ENABLING);
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}
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return true;
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}
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spi_status_t spi_transmit(const uint8_t *data, uint16_t length) {
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while (!(SPI_SERCOM->SPI.INTFLAG.bit.DRE)) {
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DBGC(DC_SPI_WRITE_DRE);
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}
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for (uint16_t i = 0; i < length; i++) {
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SPI_SERCOM->SPI.DATA.bit.DATA = data[i];
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while (!(SPI_SERCOM->SPI.INTFLAG.bit.TXC)) {
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DBGC(DC_SPI_WRITE_TXC_1);
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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 (currentSelectPin != NO_PIN) {
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gpio_set_pin_output(currentSelectPin);
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gpio_write_pin_high(currentSelectPin);
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currentSelectPin = NO_PIN;
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}
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}
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// Not implemented yet....
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spi_status_t spi_write(uint8_t data);
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spi_status_t spi_read(void);
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spi_status_t spi_receive(uint8_t *data, uint16_t length);
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