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circuitpython/drivers/bus/softspi.c

105 lines
3.8 KiB

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2016-2018 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "drivers/bus/spi.h"
int mp_soft_spi_ioctl(void *self_in, uint32_t cmd) {
mp_soft_spi_obj_t *self = (mp_soft_spi_obj_t*)self_in;
switch (cmd) {
case MP_SPI_IOCTL_INIT:
mp_hal_pin_write(self->sck, self->polarity);
mp_hal_pin_output(self->sck);
mp_hal_pin_output(self->mosi);
mp_hal_pin_input(self->miso);
break;
case MP_SPI_IOCTL_DEINIT:
break;
}
return 0;
}
void mp_soft_spi_transfer(void *self_in, size_t len, const uint8_t *src, uint8_t *dest) {
mp_soft_spi_obj_t *self = (mp_soft_spi_obj_t*)self_in;
uint32_t delay_half = self->delay_half;
// only MSB transfer is implemented
// If a port defines MICROPY_HW_SOFTSPI_MIN_DELAY, and the configured
// delay_half is equal to this value, then the software SPI implementation
// will run as fast as possible, limited only by CPU speed and GPIO time.
#ifdef MICROPY_HW_SOFTSPI_MIN_DELAY
if (delay_half == MICROPY_HW_SOFTSPI_MIN_DELAY) {
for (size_t i = 0; i < len; ++i) {
uint8_t data_out = src[i];
uint8_t data_in = 0;
for (int j = 0; j < 8; ++j, data_out <<= 1) {
mp_hal_pin_write(self->mosi, (data_out >> 7) & 1);
mp_hal_pin_write(self->sck, 1 - self->polarity);
data_in = (data_in << 1) | mp_hal_pin_read(self->miso);
mp_hal_pin_write(self->sck, self->polarity);
}
if (dest != NULL) {
dest[i] = data_in;
}
}
return;
}
#endif
for (size_t i = 0; i < len; ++i) {
uint8_t data_out = src[i];
uint8_t data_in = 0;
for (int j = 0; j < 8; ++j, data_out <<= 1) {
mp_hal_pin_write(self->mosi, (data_out >> 7) & 1);
if (self->phase == 0) {
mp_hal_delay_us_fast(delay_half);
mp_hal_pin_write(self->sck, 1 - self->polarity);
} else {
mp_hal_pin_write(self->sck, 1 - self->polarity);
mp_hal_delay_us_fast(delay_half);
}
data_in = (data_in << 1) | mp_hal_pin_read(self->miso);
if (self->phase == 0) {
mp_hal_delay_us_fast(delay_half);
mp_hal_pin_write(self->sck, self->polarity);
} else {
mp_hal_pin_write(self->sck, self->polarity);
mp_hal_delay_us_fast(delay_half);
}
}
if (dest != NULL) {
dest[i] = data_in;
}
}
}
const mp_spi_proto_t mp_soft_spi_proto = {
.ioctl = mp_soft_spi_ioctl,
.transfer = mp_soft_spi_transfer,
};