esp32-sequencer/main/esp32-sequencer.c

#include <stdio.h>
#include <stdint.h>

#include "driver/gpio.h"
#include "driver/gptimer.h"
#include "driver/ledc.h"
#include "esp_attr.h"
#include "esp_err.h"
#include "esp_log.h"
#include "esp_random.h"
#include "freertos/FreeRTOS.h"
#include "freertos/queue.h"
#include "freertos/task.h"
#include "hal/gpio_types.h"
#include "hal/ledc_types.h"
#include "hal/timer_types.h"
#include "soc/clk_tree_defs.h"

/* Inputs */
// Clock In

/* Controls */
#define GPIO_MUTATE_BTN (9) // Mutate Button In
#define GPIO_TAP_TEMPO_BTN (10) // Tap Tempo Button In

static QueueHandle_t control_event_queue = NULL;

/* Outputs */
#define GPIO_CLK_OUT (7) // Clock Out
#define GPIO_GATE_OUT (8) // Gate CV Out

/* LED GPIO Pins */
#define LEDC_CLK_OUT (5)
#define LEDC_GATE_OUT (6)

/* Timers */
static gptimer_handle_t tap_tempo_timer = NULL;
static gptimer_handle_t gate_timer = NULL;

static const uint16_t DEBOUNCE_TIMEOUT = 20; // polling period length when debouncing in ms
static uint64_t debounce_time = 0; // system time of last intterupt
static uint8_t btn_state = 1; // state of gpio last recorded

static const uint32_t DEFAULT_BPM = 120;

#define SEQ_MAX_LEN 8
static uint8_t sequence[SEQ_MAX_LEN] = {0};
static uint8_t seq_len = SEQ_MAX_LEN;

static const char *TAG = "sequencer";


uint32_t bpm_to_ms(uint32_t bpm) {
  return 60000 / bpm;
}

uint32_t ms_to_bpm(uint32_t ms) {
  return 60000 / ms;
}

static void randomize_seq(uint8_t *sequence) {
  for (uint8_t i = 0; i < SEQ_MAX_LEN; i++) {
    sequence[i] = esp_random() % 2;
  }
}

static void mutate_seq(uint8_t *sequence) {
  ESP_LOGI(TAG, "Mutating Sequence");
  // pick a step to mutate
  uint8_t step = esp_random() % SEQ_MAX_LEN;
  if (sequence[step] == 1) {
    sequence[step] = 0;
  } else if (sequence[step] == 0) {
    sequence[step] = 1;
  }
}

/* Handle tap tempo button presses */
static void tap_tempo_handler(){
  // check the count to see if we have already started the timer
  uint64_t count;
  ESP_ERROR_CHECK(gptimer_get_raw_count(tap_tempo_timer, &count));
  if (count == 0) { // the timer hasn't started yet
    ESP_ERROR_CHECK(gptimer_start(tap_tempo_timer));
    ESP_LOGI(TAG, "Starting tap tempo monitoring");
  } else { // stop the timer and calc bpm
    ESP_ERROR_CHECK(gptimer_stop(tap_tempo_timer));
    ESP_LOGI(TAG, "Stopping tap tempo monitoring at %" PRIu64 "µs", count);
  }
}

static void IRAM_ATTR gpio_isr_handler(void* arg) {
  debounce_time = xTaskGetTickCount(); // set time of interrupt
  uint32_t gpio_num = (uint32_t)arg;
  btn_state = gpio_get_level(gpio_num); // set state
  xQueueSendFromISR(control_event_queue, &gpio_num, NULL);
}

static void control_event_handler(void* arg) {
  uint32_t gpio_num;
  uint8_t last_btn_state;
  uint64_t last_debounce_time;
  while (1) {
    // save these so we can make comparisons
    last_btn_state = btn_state;
    last_debounce_time = debounce_time;
    uint8_t current_state = gpio_get_level(gpio_num);
    if (xQueueReceive(control_event_queue, &gpio_num, portMAX_DELAY)) {
      // Check if interrupt triggered stays the same for long enough
      if ((current_state == last_btn_state) &&
          (xTaskGetTickCount() - last_debounce_time > DEBOUNCE_TIMEOUT)) {
        ESP_LOGI(TAG, "Handling control from GPIO %" PRIu32, gpio_num);
        switch (gpio_num) {
        case GPIO_MUTATE_BTN:
          mutate_seq(sequence);
          break;
        case GPIO_TAP_TEMPO_BTN:
          tap_tempo_handler();
          break;
        }
      }
    }
  }
}

static void controls_init(void) {
  // install gpio isr hservice
  gpio_install_isr_service(0);
  // Setup Mutate Button
  gpio_reset_pin(GPIO_MUTATE_BTN);
  gpio_set_direction(GPIO_MUTATE_BTN, GPIO_MODE_INPUT);
  gpio_set_intr_type(GPIO_MUTATE_BTN, GPIO_INTR_NEGEDGE);
  // Hook in handler for mutate button
  gpio_isr_handler_add(GPIO_MUTATE_BTN, gpio_isr_handler, (void*)GPIO_MUTATE_BTN);

  // Setup tap tempo Button
  gpio_reset_pin(GPIO_TAP_TEMPO_BTN);
  gpio_set_direction(GPIO_TAP_TEMPO_BTN, GPIO_MODE_INPUT);
  gpio_set_intr_type(GPIO_TAP_TEMPO_BTN, GPIO_INTR_NEGEDGE);
  // Hook in handler for tap tempo button
  gpio_isr_handler_add(GPIO_TAP_TEMPO_BTN, gpio_isr_handler, (void *)GPIO_TAP_TEMPO_BTN);

  // Setup tap tempo timer
  gptimer_config_t tap_tempo_timer_config = {
      .clk_src = GPTIMER_CLK_SRC_DEFAULT,
      .direction = GPTIMER_COUNT_UP,
      .resolution_hz = 1 * 1000 * 1000 // 1MHz; 1 tick = 1 µs
  };
  ESP_ERROR_CHECK(gptimer_new_timer(&tap_tempo_timer_config, &tap_tempo_timer));
  ESP_ERROR_CHECK(gptimer_enable(tap_tempo_timer));
}

static void gate_off_alarm_cb(gptimer_handle_t timer, const gptimer_alarm_event_data_t *edata, void *user_data) {
  gptimer_stop(gate_timer);
  gpio_set_level(GPIO_GATE_OUT, 0);
  gpio_set_level(GPIO_CLK_OUT, 0);
  ESP_ERROR_CHECK(ledc_set_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_1, 0));
  ESP_ERROR_CHECK(ledc_update_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_1));
  ESP_ERROR_CHECK(ledc_set_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_0, 0));
  ESP_ERROR_CHECK(ledc_update_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_0));
}

static void gpio_init(void) {
  // Setup gpio control event queue
  control_event_queue = xQueueCreate(10, sizeof(uint32_t));
  // Setup Clock CV Output
  gpio_reset_pin(GPIO_CLK_OUT);
  gpio_set_direction(GPIO_CLK_OUT, GPIO_MODE_OUTPUT);
  // Setup Gate CV Output
  gpio_reset_pin(GPIO_GATE_OUT);
  gpio_set_direction(GPIO_GATE_OUT, GPIO_MODE_OUTPUT);

  // Setup gate timer
  gptimer_config_t cv_out_timer_config = {
    .clk_src = GPTIMER_CLK_SRC_DEFAULT,
    .direction = GPTIMER_COUNT_UP,
    .resolution_hz = 1 * 1000 * 1000 // 1MHz; 1 tick = 1 µs
  };
  ESP_ERROR_CHECK(gptimer_new_timer(&cv_out_timer_config, &gate_timer));

  // Configure gate timer alarm
  gptimer_alarm_config_t cv_off_alarm_config = {
    .alarm_count = 20 * 1000, // 20ms @ 1MHz
    .reload_count = 0,
    .flags.auto_reload_on_alarm = true
  };
  ESP_ERROR_CHECK(gptimer_set_alarm_action(gate_timer, &cv_off_alarm_config));

  //register gate timer callback
  gptimer_event_callbacks_t clk_cbs = {.on_alarm = gate_off_alarm_cb};
  ESP_ERROR_CHECK(gptimer_register_event_callbacks(gate_timer, &clk_cbs, NULL));
  ESP_ERROR_CHECK(gptimer_enable(gate_timer));
}

static void ledc_init(void) {
  // Setup LEDC PWM timer configuration
  ledc_timer_config_t ledc_timer = {
    .speed_mode = LEDC_LOW_SPEED_MODE,
    .timer_num = LEDC_TIMER_0,
    .duty_resolution = LEDC_TIMER_13_BIT,
    .freq_hz = 5000,
    .clk_cfg = LEDC_AUTO_CLK
  };
  ESP_ERROR_CHECK(ledc_timer_config(&ledc_timer));

  // Setup Clock LED
  ledc_channel_config_t ledc_clk_channel = {
    .channel = LEDC_CHANNEL_0,
    .gpio_num = LEDC_CLK_OUT,
    .speed_mode = LEDC_LOW_SPEED_MODE,
    .timer_sel = LEDC_TIMER_0,
    .intr_type = LEDC_INTR_DISABLE,
    .duty = 0,
    .hpoint = 0
  };
  ESP_ERROR_CHECK(ledc_channel_config(&ledc_clk_channel));

  // Setup Gate LED
  ledc_channel_config_t ledc_gate_channel = {
    .channel = LEDC_CHANNEL_1,
    .gpio_num = LEDC_GATE_OUT,
    .speed_mode = LEDC_LOW_SPEED_MODE,
    .timer_sel = LEDC_TIMER_0,
    .intr_type = LEDC_INTR_DISABLE,
    .duty = 0,
    .hpoint = 0
  };
  ESP_ERROR_CHECK(ledc_channel_config(&ledc_gate_channel));
}

static void pulse_cv(bool triggered) {
  ESP_ERROR_CHECK(gptimer_start(gate_timer));
  ESP_ERROR_CHECK(ledc_set_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_0, 4095));
  ESP_ERROR_CHECK(ledc_update_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_0));
  gpio_set_level(GPIO_CLK_OUT, 1);
  if (triggered) {
    gpio_set_level(GPIO_GATE_OUT, 1);
    ESP_ERROR_CHECK(ledc_set_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_1, 4095));
    ESP_ERROR_CHECK(ledc_update_duty(LEDC_LOW_SPEED_MODE, LEDC_CHANNEL_1));
  }
}

void app_main(void) {
  /* Initialize Peripherals */
  /* Initialize GPIO */
  gpio_init();
  controls_init();
  // Start task to handle control events
  xTaskCreate(control_event_handler, "control event handler", 2048, NULL, 10, NULL);

  /* Initialize Monitor LEDs */
  ledc_init();

  /* Initialize sequence */
  randomize_seq(sequence);

  /* Main Loop */
  while (1) {
    for (uint8_t step = 0; step < seq_len; step++) {
      // if step has been set for sequence
      if (sequence[step] == 1) {
        pulse_cv(true);
      } else {
        pulse_cv(false);
      }
      printf("%i", sequence[step]);
      vTaskDelay(bpm_to_ms(DEFAULT_BPM)/ portTICK_PERIOD_MS);
    }
    printf("\n");

  }
}