rmt_pulse.c

#include "rmt_pulse.h"
#include "driver/rmt.h"
#include "esp_system.h"

static intr_handle_t gRMT_intr_handle = NULL;

// the RMT channel configuration object
static rmt_config_t row_rmt_config;

// keep track of wether the current pulse is ongoing
volatile bool rmt_tx_done = true;

/**
 * Remote peripheral interrupt. Used to signal when transmission is done.
 */
static void IRAM_ATTR rmt_interrupt_handler(void *arg) {
  rmt_tx_done = true;
  RMT.int_clr.val = RMT.int_st.val;
}

void rmt_pulse_init(gpio_num_t pin) {

  row_rmt_config.rmt_mode = RMT_MODE_TX;
  // currently hardcoded: use channel 0
  row_rmt_config.channel = RMT_CHANNEL_1;

  row_rmt_config.gpio_num = pin;
  row_rmt_config.mem_block_num = 2;

  // Divide 80MHz APB Clock by 8 -> .1us resolution delay
  row_rmt_config.clk_div = 8;

  row_rmt_config.tx_config.loop_en = false;
  row_rmt_config.tx_config.carrier_en = false;
  row_rmt_config.tx_config.carrier_level = RMT_CARRIER_LEVEL_LOW;
  row_rmt_config.tx_config.idle_level = RMT_IDLE_LEVEL_LOW;
  row_rmt_config.tx_config.idle_output_en = true;

  #if ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(4, 2, 0) && ESP_IDF_VERSION > ESP_IDF_VERSION_VAL(4, 0, 2)
    #error "This driver is not compatible with IDF version 4.1.\nPlease use 4.0 or >= 4.2!"
  #endif
  esp_intr_alloc(ETS_RMT_INTR_SOURCE, ESP_INTR_FLAG_LEVEL3,
                 rmt_interrupt_handler, 0, &gRMT_intr_handle);

  rmt_config(&row_rmt_config);
  rmt_set_tx_intr_en(row_rmt_config.channel, true);
}

void IRAM_ATTR pulse_ckv_ticks(uint16_t high_time_ticks,
                               uint16_t low_time_ticks, bool wait) {
  while (!rmt_tx_done) {
  };
  volatile rmt_item32_t *rmt_mem_ptr =
      &(RMTMEM.chan[row_rmt_config.channel].data32[0]);
  if (high_time_ticks > 0) {
    rmt_mem_ptr->level0 = 1;
    rmt_mem_ptr->duration0 = high_time_ticks;
    rmt_mem_ptr->level1 = 0;
    rmt_mem_ptr->duration1 = low_time_ticks;
  } else {
    rmt_mem_ptr->level0 = 1;
    rmt_mem_ptr->duration0 = low_time_ticks;
    rmt_mem_ptr->level1 = 0;
    rmt_mem_ptr->duration1 = 0;
  }
  RMTMEM.chan[row_rmt_config.channel].data32[1].val = 0;
  rmt_tx_done = false;
  RMT.conf_ch[row_rmt_config.channel].conf1.mem_rd_rst = 1;
  RMT.conf_ch[row_rmt_config.channel].conf1.mem_owner = RMT_MEM_OWNER_TX;
  RMT.conf_ch[row_rmt_config.channel].conf1.tx_start = 1;
  while (wait && !rmt_tx_done) {
  };
}

void IRAM_ATTR pulse_ckv_us(uint16_t high_time_us, uint16_t low_time_us,
                            bool wait) {
  pulse_ckv_ticks(10 * high_time_us, 10 * low_time_us, wait);
}

bool IRAM_ATTR rmt_busy() { return !rmt_tx_done; }