122 lines
3.8 KiB
C
122 lines
3.8 KiB
C
/* sd_spi.c
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Copyright 2021 Carl John Kugler III
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Licensed under the Apache License, Version 2.0 (the License); you may not use
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this file except in compliance with the License. You may obtain a copy of the
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License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software distributed
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under the License is distributed on an AS IS BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied. See the License for the
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specific language governing permissions and limitations under the License.
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*/
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/* Standard includes. */
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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//
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#include "hardware/gpio.h"
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//
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#include "my_debug.h"
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#include "sd_card.h"
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#include "sd_spi.h"
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#include "spi.h"
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//#define TRACE_PRINTF(fmt, args...)
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#define TRACE_PRINTF printf // task_printf
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void sd_spi_go_high_frequency(sd_card_t *pSD) {
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uint actual = spi_set_baudrate(pSD->spi->hw_inst, pSD->spi->baud_rate);
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TRACE_PRINTF("%s: Actual frequency: %lu\n", __FUNCTION__, (long)actual);
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}
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void sd_spi_go_low_frequency(sd_card_t *pSD) {
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uint actual = spi_set_baudrate(pSD->spi->hw_inst, 400 * 1000); // Actual frequency: 398089
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TRACE_PRINTF("%s: Actual frequency: %lu\n", __FUNCTION__, (long)actual);
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}
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static void sd_spi_lock(sd_card_t *pSD) {
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spi_lock(pSD->spi);
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}
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static void sd_spi_unlock(sd_card_t *pSD) {
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spi_unlock(pSD->spi);
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}
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// Would do nothing if pSD->ss_gpio were set to GPIO_FUNC_SPI.
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static void sd_spi_select(sd_card_t *pSD) {
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gpio_put(pSD->ss_gpio, 0);
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// A fill byte seems to be necessary, sometimes:
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uint8_t fill = SPI_FILL_CHAR;
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spi_write_blocking(pSD->spi->hw_inst, &fill, 1);
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LED_ON();
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}
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static void sd_spi_deselect(sd_card_t *pSD) {
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gpio_put(pSD->ss_gpio, 1);
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LED_OFF();
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/*
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MMC/SDC enables/disables the DO output in synchronising to the SCLK. This
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means there is a posibility of bus conflict with MMC/SDC and another SPI
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slave that shares an SPI bus. Therefore to make MMC/SDC release the MISO
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line, the master device needs to send a byte after the CS signal is
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deasserted.
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*/
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uint8_t fill = SPI_FILL_CHAR;
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spi_write_blocking(pSD->spi->hw_inst, &fill, 1);
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}
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/* Some SD cards want to be deselected between every bus transaction */
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void sd_spi_deselect_pulse(sd_card_t *pSD) {
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sd_spi_deselect(pSD);
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// tCSH Pulse duration, CS high 200 ns
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sd_spi_select(pSD);
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}
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void sd_spi_acquire(sd_card_t *pSD) {
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sd_spi_lock(pSD);
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sd_spi_select(pSD);
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}
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void sd_spi_release(sd_card_t *pSD) {
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sd_spi_deselect(pSD);
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sd_spi_unlock(pSD);
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}
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bool sd_spi_transfer(sd_card_t *pSD, const uint8_t *tx, uint8_t *rx,
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size_t length) {
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return spi_transfer(pSD->spi, tx, rx, length);
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}
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uint8_t sd_spi_write(sd_card_t *pSD, const uint8_t value) {
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// TRACE_PRINTF("%s\n", __FUNCTION__);
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uint8_t received = SPI_FILL_CHAR;
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#if 0
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int num = spi_write_read_blocking(pSD->spi->hw_inst, &value, &received, 1);
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myASSERT(1 == num);
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#else
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bool success = spi_transfer(pSD->spi, &value, &received, 1);
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myASSERT(success);
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#endif
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return received;
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}
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void sd_spi_send_initializing_sequence(sd_card_t * pSD) {
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bool old_ss = gpio_get(pSD->ss_gpio);
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// Set DI and CS high and apply 74 or more clock pulses to SCLK:
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gpio_put(pSD->ss_gpio, 1);
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uint8_t ones[10];
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memset(ones, 0xFF, sizeof ones);
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absolute_time_t timeout_time = make_timeout_time_ms(1);
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do {
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sd_spi_transfer(pSD, ones, NULL, sizeof ones);
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} while (0 < absolute_time_diff_us(get_absolute_time(), timeout_time));
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gpio_put(pSD->ss_gpio, old_ss);
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}
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void sd_spi_init_pl022(sd_card_t *pSD) {
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// Let the PL022 SPI handle it.
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// the CS line is brought high between each byte during transmission.
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gpio_set_function(pSD->ss_gpio, GPIO_FUNC_SPI);
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}
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/* [] END OF FILE */
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