Tape loading from GPIO

firmware/src/GPIOTapeLoader/GPIOTapeLoader.cpp

@@ -0,0 +1,58 @@
+#include <Arduino.h>
+#include <freertos/FreeRTOS.h>
+#include <driver/adc.h>
+#include <driver/timer.h>
+#include "GPIOTapeLoader.h"
+
+#define TAPE_TIMER_GROUP TIMER_GROUP_1
+
+IRAM_ATTR bool onTimer(void *param) {
+  GPIOTapeLoader *loader = (GPIOTapeLoader *)param;
+  // read from the ADC
+  uint16_t sample = adc1_get_raw(ADC1_CHANNEL_4);
+
+  if (sample > 2048) {
+    ledcWrite(0, 10);
+  } else {
+    ledcWrite(0, 0);
+  }
+  // uint16_t sample = digitalRead(5) == LOW ? 4095 : 0;
+  // push the sample on the queue
+  BaseType_t higherPriorityTaskWoken = pdFALSE;
+  xQueueSendFromISR(loader->sampleQueue, &sample, &higherPriorityTaskWoken);
+  return higherPriorityTaskWoken == pdTRUE;
+}
+
+void launchTimer(void *param) {
+  GPIOTapeLoader *loader = (GPIOTapeLoader *)param;
+        // set up the ADC
+      adc1_config_width(ADC_WIDTH_BIT_12);
+      adc1_config_channel_atten(ADC1_CHANNEL_4, ADC_ATTEN_DB_12);
+      // pinMode(5, INPUT);
+      // create a timer that will fire at the sample rate
+      timer_config_t timer_config = {
+          .alarm_en = TIMER_ALARM_EN,
+          .counter_en = TIMER_PAUSE,
+          .intr_type = TIMER_INTR_LEVEL,
+          .counter_dir = TIMER_COUNT_UP,
+          .auto_reload = TIMER_AUTORELOAD_EN,
+          .divider = 80,
+          .clk_src = TIMER_SRC_CLK_APB
+      };
+      ESP_ERROR_CHECK(timer_init(TAPE_TIMER_GROUP, TIMER_0, &timer_config));
+      ESP_ERROR_CHECK(timer_set_counter_value(TAPE_TIMER_GROUP, TIMER_0, 0));
+      ESP_ERROR_CHECK(timer_set_alarm_value(TAPE_TIMER_GROUP, TIMER_0, 1000000 / loader->sampleRate));
+      ESP_ERROR_CHECK(timer_enable_intr(TAPE_TIMER_GROUP, TIMER_0));
+      ESP_ERROR_CHECK(timer_isr_callback_add(TAPE_TIMER_GROUP, TIMER_0, onTimer, loader, ESP_INTR_FLAG_IRAM));
+      ESP_ERROR_CHECK(timer_start(TAPE_TIMER_GROUP, TIMER_0));
+      while(1) {
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+        if (loader->state == GPIOTapeLoaderState::PAUSING) {
+          timer_pause(TAPE_TIMER_GROUP, TIMER_0);
+          loader->state = GPIOTapeLoaderState::STOPPED;
+        } else if (loader->state == GPIOTapeLoaderState::STARTING) {
+          timer_start(TAPE_TIMER_GROUP, TIMER_0);
+          loader->state = GPIOTapeLoaderState::RUNNING;
+        }
+      }
+}

firmware/src/GPIOTapeLoader/GPIOTapeLoader.h

@@ -0,0 +1,57 @@
+#pragma once
+
+#include <freertos/FreeRTOS.h>
+#include <driver/adc.h>
+#include <driver/timer.h>
+
+
+IRAM_ATTR bool onTimer(void *param);
+void launchTimer(void *param);
+
+enum GPIOTapeLoaderState {
+  STARTING,
+  RUNNING,
+  PAUSING,
+  STOPPED
+};
+
+class GPIOTapeLoader
+{
+  private:
+    // queue to hold samples read from the ADC
+    xQueueHandle sampleQueue;
+    friend IRAM_ATTR bool onTimer(void *param);
+    friend void launchTimer(void *param);
+    int sampleRate;
+    GPIOTapeLoaderState state = STOPPED;
+  public:
+    GPIOTapeLoader(uint32_t sample_rate) {
+      sampleRate = sample_rate;
+      // create a queue to hold the values read from the ADC
+      sampleQueue = xQueueCreate(16384, sizeof(uint16_t));
+      xTaskCreatePinnedToCore(launchTimer, "launchTimer", 8192, this, 1, NULL, 0);
+    }
+    void start() {
+      if (state == STARTING) return;
+      state = STARTING;
+    }
+    void stop() {
+      if (state == PAUSING) return;
+      state = PAUSING;
+    }
+    void pause() {
+      if (state == PAUSING) return;
+      state = PAUSING;
+    }
+    void resume() {
+      if (state == STARTING) return;
+      state = STARTING;
+    }
+    uint16_t readSample() {
+      uint16_t sample;
+      if (xQueueReceive(sampleQueue, &sample, portMAX_DELAY)) {
+        return sample;
+      }
+      return -1;
+    }
+};