Part 6: Audio

src/CMakeLists.txt

@@ -1,6 +1,7 @@
 idf_component_register(
 	SRCS
 	"main.c"
+	"odroid/audio.c"
 	"odroid/battery.c"
 	"odroid/display.c"
 	"odroid/input.c"

src/main.c

@@ -1,3 +1,4 @@
+#include "odroid/audio.h"
 #include "odroid/battery.h"
 #include "odroid/display.h"
 #include "odroid/input.h"
@@ -12,12 +13,14 @@
 static const char* LOG_TAG = "Main";
 static uint16_t gFramebuffer[LCD_WIDTH * LCD_HEIGHT];
 
+
 void app_main(void)
 {
 	Odroid_InitializeInput();
 	Odroid_InitializeDisplay();
 	Odroid_InitializeSdcard();
 	Odroid_InitializeBatteryReader();
+	Odroid_InitializeAudio();
 
 	// Load sprite
 	uint16_t* sprite = (uint16_t*)malloc(64 * 64 * sizeof(uint16_t));
@@ -36,6 +39,28 @@ void app_main(void)
 		fclose(spriteFile);
 	}
 
+	// Load sound effect
+	uint16_t* soundBuffer;
+	int soundEffectLength = 1441;
+	{
+		FILE* soundFile = fopen("/sdcard/jump", "r");
+		assert(soundFile);
+
+		uint8_t* soundEffect = malloc(soundEffectLength);
+		assert(soundEffect);
+
+		soundBuffer = malloc(soundEffectLength*2);
+		assert(soundBuffer);
+
+		fread(soundEffect, soundEffectLength, 1, soundFile);
+
+		for (int i = 0; i < soundEffectLength; ++i)
+		{
+			// 16 bits required but only MSB is actually sent to the DAC
+			soundBuffer[i] = (soundEffect[i] << 8u);
+		}
+	}
+
 
 	ESP_LOGI(LOG_TAG, "Odroid initialization complete - entering main loop");
 
@@ -44,6 +69,8 @@ void app_main(void)
 
 	uint16_t color = 0xffff;
 
+	int lastState = 0;
+
 	for (;;)
 	{
 		memset(gFramebuffer, 0, 320 * 240 * 2);
@@ -61,6 +88,17 @@ void app_main(void)
 		else if (input.start) { color = SWAP_ENDIAN_16(RGB565(0, 0, 0xff)); }
 		else if (input.select) { color = SWAP_ENDIAN_16(RGB565(0xff, 0xff, 0xff)); }
 
+
+		int thisState = input.volume;
+
+		if ((thisState == 1) && (thisState != lastState))
+		{
+			Odroid_PlayAudio(soundBuffer, soundEffectLength*2);
+		}
+
+		lastState = thisState;
+
+
 		int spriteRow = 0;
 		int spriteCol = 0;
 

src/odroid/audio.c

@@ -0,0 +1,85 @@
+#include "audio.h"
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+#include <driver/i2s.h>
+
+
+static const gpio_num_t AUDIO_AMP_SD_PIN = GPIO_NUM_25;
+
+static QueueHandle_t gQueue;
+
+
+typedef struct
+{
+	uint16_t* buffer;
+	int length;
+} QueueData;
+
+
+static void PlayTask(void *arg)
+{
+	for(;;)
+	{
+		QueueData data;
+
+		if (xQueueReceive(gQueue, &data, 10))
+		{
+			size_t bytesWritten;
+			i2s_write(I2S_NUM_0, data.buffer, data.length, &bytesWritten, portMAX_DELAY);
+			i2s_zero_dma_buffer(I2S_NUM_0);
+		}
+
+		vTaskDelay(1 / portTICK_PERIOD_MS);
+	}
+}
+
+void Odroid_InitializeAudio(void)
+{
+	// Configure the amplifier shutdown signal
+	{
+		gpio_config_t gpioConfig = {};
+
+		gpioConfig.mode = GPIO_MODE_OUTPUT;
+		gpioConfig.pin_bit_mask = 1ULL << AUDIO_AMP_SD_PIN;
+
+		ESP_ERROR_CHECK(gpio_config(&gpioConfig));
+
+		gpio_set_level(AUDIO_AMP_SD_PIN, 1);
+	}
+
+	// Configure the I2S driver
+	{
+		i2s_config_t i2sConfig= {};
+
+		i2sConfig.mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN;
+		i2sConfig.sample_rate = 5512;
+		i2sConfig.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT;
+		i2sConfig.communication_format = I2S_COMM_FORMAT_I2S_MSB;
+		i2sConfig.channel_format = I2S_CHANNEL_FMT_ONLY_LEFT;
+		i2sConfig.dma_buf_count = 8;
+		i2sConfig.dma_buf_len = 64;
+
+		ESP_ERROR_CHECK(i2s_driver_install(I2S_NUM_0, &i2sConfig, 0, NULL));
+		ESP_ERROR_CHECK(i2s_set_dac_mode(I2S_DAC_CHANNEL_LEFT_EN));
+	}
+
+	// Create task for playing sounds so that our main task isn't blocked
+	{
+		gQueue = xQueueCreate(1, sizeof(QueueData));
+		assert(gQueue);
+
+		BaseType_t result = xTaskCreatePinnedToCore(&PlayTask, "I2S Task", 1024, NULL, 5, NULL, 1);
+		assert(result == pdPASS);
+	}
+}
+
+void Odroid_PlayAudio(uint16_t* buffer, int length)
+{
+	QueueData data = {};
+
+	data.buffer = buffer;
+	data.length = length;
+
+	xQueueSendToBack(gQueue, &data, portMAX_DELAY);
+}
+

src/odroid/audio.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include <stdint.h>
+
+
+void Odroid_InitializeAudio(void);
+void Odroid_PlayAudio(uint16_t* buffer, int length);
+