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105 lines
2.7 KiB
C
105 lines
2.7 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 ESP32 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 "xtensa/core-macros.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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static inline __attribute__((always_inline)) uint32_t get_cycle_count(void) {
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uint32_t ccount;
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__asm__ __volatile__("rsr %0,ccount":"=a" (ccount));
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return ccount;
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}
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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 = rtc_clk_cpu_freq_value(rtc_clk_cpu_freq_get());
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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=%d\n", freq, total_cycles);
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DEBUG("[ws281x] esp32 cycles %d/%d/%d/%d\n", 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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start = 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 (get_cycle_count() < current_wait) { }
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gpio_clear(dev->params.pin);
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start = get_cycle_count();
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current_wait = start + off_wait;
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while (get_cycle_count() < current_wait) { }
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data <<= 1;
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}
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pos++;
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}
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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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