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c40e015804
If overhead like the loop control or the calculation of the waiting times for the next bit are performed while waiting for the end of the LOW phase, the time required for such operations is included in the LOW phase. This makes both the LOW phase and the period more precise.
107 lines
2.8 KiB
C
107 lines
2.8 KiB
C
/*
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* Copyright 2020 Christian Friedrich Coors
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup drivers_ws281x
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*
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* @{
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*
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* @file
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* @brief Implementation of `ws281x_write_buffer()` for the ESP32x CPU
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*
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* @author Christian Friedrich Coors <me@ccoors.de>
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*
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* @}
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*/
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#include <assert.h>
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#include <errno.h>
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#include <stdint.h>
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#include <string.h>
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#include "ws281x.h"
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#include "ws281x_params.h"
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#include "ws281x_constants.h"
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#include "periph_cpu.h"
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#include "esp_private/esp_clk.h"
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#include "hal/cpu_hal.h"
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#include "soc/rtc.h"
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#define ENABLE_DEBUG 0
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#include "debug.h"
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void ws281x_write_buffer(ws281x_t *dev, const void *buf, size_t size)
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{
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assert(dev);
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const uint8_t *pos = buf;
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const uint8_t *end = pos + size;
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/* Cycles */
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uint32_t total_cycles, one_on, one_off, zero_on, zero_off, on_wait, off_wait;
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/* Current frequency */
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rtc_cpu_freq_t freq = esp_clk_cpu_freq();
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total_cycles = freq / (NS_PER_SEC / WS281X_T_DATA_NS);
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one_on = freq / (NS_PER_SEC / WS281X_T_DATA_ONE_NS);
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one_off = total_cycles - one_on;
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zero_on = freq / (NS_PER_SEC / WS281X_T_DATA_ZERO_NS);
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zero_off = total_cycles - zero_on;
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DEBUG("[ws281x] esp32 freq=%d total=%"PRIu32"\n", freq, total_cycles);
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DEBUG("[ws281x] esp32 cycles %"PRIu32"/%"PRIu32"/%"PRIu32"/%"PRIu32"\n",
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one_on, one_off, zero_on, zero_off);
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uint32_t current_wait = 0, start = 0;
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while (pos < end) {
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uint8_t data = *pos;
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for (uint8_t cnt = 8; cnt > 0; cnt--) {
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if (data & 0b10000000) {
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on_wait = one_on;
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off_wait = one_off;
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}
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else {
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on_wait = zero_on;
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off_wait = zero_off;
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}
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data <<= 1;
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while (cpu_hal_get_cycle_count() < current_wait) { }
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/* end of LOW phase and start of HIGH phase */
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start = cpu_hal_get_cycle_count();
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gpio_set(dev->params.pin);
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current_wait = start + on_wait;
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while (cpu_hal_get_cycle_count() < current_wait) { }
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/* end of HIGH phase and start of HIGH phase */
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start = cpu_hal_get_cycle_count();
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gpio_clear(dev->params.pin);
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current_wait = start + off_wait;
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}
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pos++;
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}
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/* final LOW phase */
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current_wait = cpu_hal_get_cycle_count();
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/* end of final LOW phase */
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}
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int ws281x_init(ws281x_t *dev, const ws281x_params_t *params)
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{
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if (!dev || !params || !params->buf) {
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return -EINVAL;
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}
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memset(dev, 0, sizeof(ws281x_t));
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dev->params = *params;
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if (gpio_init(dev->params.pin, GPIO_OUT)) {
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return -EIO;
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}
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return 0;
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}
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