Refactor: beat tempo now works off of a timer instead of manual delay

main/esp32-sequencer.c

@@ -77,6 +77,7 @@ static QueueHandle_t control_event_queue = NULL;
 /* Timers */
 static gptimer_handle_t tap_tempo_timer = NULL;
 static gptimer_handle_t gate_timer = NULL;
+static gptimer_handle_t tempo_timer = NULL;
 
 static const uint16_t DEBOUNCE_TIMEOUT = 10; /* polling period length when debouncing in ms */
 static uint64_t debounce_time = 0; /* system time of last intterupt */
@@ -88,9 +89,12 @@ static const uint32_t DEFAULT_BPM = 120;
 static uint16_t current_bpm = DEFAULT_BPM;
 lv_obj_t * bpm_label = NULL;
 
+TaskHandle_t tempo_handle;
+
 #define SEQ_MAX_LEN 8
 static uint8_t sequence[SEQ_MAX_LEN] = {0};
 static uint8_t seq_len = SEQ_MAX_LEN;
+uint8_t current_step = 0;
 lv_obj_t * sequence_label = NULL;
 lv_obj_t * sequence_tracker = NULL;
 
@@ -105,8 +109,26 @@ uint32_t ms_to_bpm(uint32_t ms) {
   return 60000 / ms;
 }
 
+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));
+  }
+}
+
 static void update_bpm(void) {
   lv_label_set_text_fmt(bpm_label, "BPM: %d", current_bpm);
+  gptimer_alarm_config_t tempo_alarm_config = {
+    .reload_count = 0,
+    .flags.auto_reload_on_alarm = true,
+    .alarm_count = bpm_to_ms(current_bpm) * 1000
+  };
+  ESP_ERROR_CHECK(gptimer_set_alarm_action(tempo_timer, &tempo_alarm_config));
 }
 
 /* updates the sequence for the GUI display */
@@ -159,6 +181,70 @@ static void tap_tempo_handler(){
   }
 }
 
+/* Essentially the Main Loop. Runs the tempo timer to trigger beat related events */
+static void tempo_task(void *pvParameter) {
+  /* Start the timer */
+  ESP_ERROR_CHECK(gptimer_start(tempo_timer));
+  uint32_t ulInterruptStatus;
+
+  /* Loop that waits for notification of beat end */
+  while (1) {
+    xTaskNotifyWait(0, ULONG_MAX, &ulInterruptStatus , portMAX_DELAY);
+
+    /* Pulse outputs if step is active */
+    if (sequence[current_step] == 1) {
+      pulse_cv(true);
+    } else {
+      pulse_cv(false);
+    }
+
+    /* Construct a string for the sequence tracker display */
+    char tracker_str[] = "        ";
+    tracker_str[current_step] = '_';
+
+    /* set the new sequence label */
+    lv_label_set_text(sequence_tracker, tracker_str);
+
+    /* Advance the Step */
+    if (current_step == seq_len - 1) {
+      current_step = 0;
+    } else {
+      current_step++;
+    }
+  }
+}
+
+/* Handler that runs when the tempo timer goes off */
+static void tempo_timer_cb(void * arg) {
+  BaseType_t xHigherPriorityTaskWoken;
+  xTaskNotifyFromISR(tempo_handle , 0, eSetBits, &xHigherPriorityTaskWoken);
+}
+
+/* Initialize tempo timer */
+static void tempo_init(void) {
+  /* Setup timer */
+  gptimer_config_t tempo_timer_config = {
+    .clk_src = GPTIMER_CLK_SRC_DEFAULT,
+    .direction = GPTIMER_COUNT_UP,
+    .resolution_hz = 1 * 1000 * 1000 /* 1MHz; 1 tick = 1µs */
+  };
+  ESP_ERROR_CHECK(gptimer_new_timer(&tempo_timer_config, &tempo_timer));
+
+  /* Configure alarm to go off based on BPM */
+  gptimer_alarm_config_t tempo_alarm_config = {
+      .reload_count = 0,
+      .flags.auto_reload_on_alarm = true,
+      .alarm_count = bpm_to_ms(current_bpm) * 1000};
+  ESP_ERROR_CHECK(gptimer_set_alarm_action(tempo_timer, &tempo_alarm_config));
+
+  /* Setup tempo callback */
+  gptimer_event_callbacks_t cb_config = {
+    .on_alarm = tempo_timer_cb
+  };
+  ESP_ERROR_CHECK(gptimer_register_event_callbacks(tempo_timer, &cb_config, NULL));
+  ESP_ERROR_CHECK(gptimer_enable(tempo_timer));
+}
+
 static void IRAM_ATTR gpio_isr_handler(void* arg) {
   uint32_t gpio_num = (uint32_t)arg;
   portENTER_CRITICAL_ISR(&mux);
@@ -466,18 +552,6 @@ static void gui_task(void *pvParameter) {
   }
 }
 
-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 */
@@ -498,28 +572,9 @@ void app_main(void) {
   /* Initialize sequence */
   randomize_seq(sequence);
 
-  /* Main Loop */
+  /* Initialize tempo timer */
-  while (1) {
+  tempo_init();
-    char  tracker_str[seq_len];
-    for (uint8_t step = 0; step < seq_len; step++) {
-      /* advance step tracker */
-      if (step == 0) {
-        tracker_str[seq_len - 1] = ' ';
-      } else {
-        tracker_str[step - 1] = ' ';
-      }
-      tracker_str[step] = '_';
 
-      /* set the new sequence label */
+  /* start main beat tempo loop task */
-      lv_label_set_text(sequence_tracker, tracker_str);
+  xTaskCreate(tempo_task, "tempo", 2048, NULL, 0, &tempo_handle);
-
-      /* if step has been set for sequence */
-      if (sequence[step] == 1) {
-        pulse_cv(true);
-      } else {
-        pulse_cv(false);
-      }
-      vTaskDelay(bpm_to_ms(current_bpm)/ portTICK_PERIOD_MS);
-    }
-  }
 }