Part 4: drive

Modification of ESP-IDF

// Initialize SPI bus
esp_err_t ret = spi_bus_initialize((spi_host_device_t)slot, &buscfg,
    slot_config->dma_channel);
if (ret != ESP_OK) {
    ESP_LOGD(TAG, "spi_bus_initialize failed with rc=0x%x", ret);
    //return ret;
}

Initialization

8.3, . , fopen . make menuconfig, , 8.3.

FILE* spriteFile = fopen("/sdcard/key", "r");
assert(spriteFile);

uint16_t* sprite = (uint16_t*)malloc(64 * 64 * sizeof(uint16_t));

for (int i = 0; i < 64; ++i)
{
	for (int j = 0; j < 64; ++j)
	{
		fread(sprite, sizeof(uint16_t), 64 * 64, spriteFile);
	}
}

fclose(spriteFile);

int spriteRow = 0;
int spriteCol = 0;

for (int row = y; row < y + 64; ++row)
{
	spriteCol = 0;

	for (int col = x; col < x + 64; ++col)
	{
		uint16_t pixelColor = sprite[64 * spriteRow + spriteCol];

		if (pixelColor != 0)
		{
			gFramebuffer[row * LCD_WIDTH + col] = color;
		}

		++spriteCol;
	}

	++spriteRow;
}

if (input.menu)
{
	const char* snapFilename = "/sdcard/framebuf";

	ESP_LOGI(LOG_TAG, "Writing snapshot to %s", snapFilename);

	FILE* snapFile = fopen(snapFilename, "wb");
	assert(snapFile);

		fwrite(gFramebuffer, sizeof(gFramebuffer[0]), LCD_WIDTH * LCD_HEIGHT, snapFile);
	}

	fclose(snapFile);
}

convert -depth 16 -size 320x240+0 -endian msb rgb565:FRAMEBUF snap.png

References

• Odroid go schematic
• ESP-IDF Documentation: SDMMC

Part 5: battery

Scheme

Status LED

Initialization

static const adc1_channel_t BATTERY_READ_PIN = ADC1_GPIO36_CHANNEL;
static const gpio_num_t BATTERY_LED_PIN = GPIO_NUM_2;

static esp_adc_cal_characteristics_t gCharacteristics;

void Odroid_InitializeBatteryReader()
{
	// Configure LED
	{
		gpio_config_t gpioConfig = {};

		gpioConfig.mode = GPIO_MODE_OUTPUT;
		gpioConfig.pin_bit_mask = 1ULL << BATTERY_LED_PIN;

		ESP_ERROR_CHECK(gpio_config(&gpioConfig));
	}

	// Configure ADC
	{
		adc1_config_width(ADC_WIDTH_BIT_12);
    	adc1_config_channel_atten(BATTERY_READ_PIN, ADC_ATTEN_DB_11);
    	adc1_config_channel_atten(BATTERY_READ_PIN, ADC_ATTEN_DB_11);

    	esp_adc_cal_value_t type = esp_adc_cal_characterize(
    		ADC_UNIT_1, ADC_ATTEN_DB_11, ADC_WIDTH_BIT_12, 1100, &gCharacteristics);

    	assert(type == ESP_ADC_CAL_VAL_EFUSE_VREF);
    }

	ESP_LOGI(LOG_TAG, "Battery reader initialized");
}

Battery Read

uint32_t Odroid_ReadBatteryLevel(void)
{
	const int SAMPLE_COUNT = 20;


	uint32_t raw = 0;

	for (int sampleIndex = 0; sampleIndex < SAMPLE_COUNT; ++sampleIndex)
	{
		raw += adc1_get_raw(BATTERY_READ_PIN);
	}

	raw /= SAMPLE_COUNT;


	uint32_t voltage = 2 * esp_adc_cal_raw_to_voltage(raw, &gCharacteristics);

	return voltage;
}

LED setting

void Odroid_EnableBatteryLight(void)
{
	gpio_set_level(BATTERY_LED_PIN, 1);
}

void Odroid_DisableBatteryLight(void)
{
	gpio_set_level(BATTERY_LED_PIN, 0);
}

Demo

uint32_t batteryLevel = Odroid_ReadBatteryLevel();

if (batteryLevel < 3600)
{
	Odroid_EnableBatteryLight();
}
else
{
	Odroid_DisableBatteryLight();
}

References

• Odroid go schematic
• ESP-IDF Documentation: ADC
• Battery characteristics

Part 6: sound

Digital Sound Basics

Record

Play

Sampling rate

Bit depth

Wav files

I2S

1. We transfer audio data to the I2S driver
2. I2S driver sends audio data to 8-bit internal DAC
3. The internal DAC outputs an analog signal
4. The analog signal is transmitted to the sound amplifier

Multitasking

Initialization

static const gpio_num_t AUDIO_AMP_SD_PIN = GPIO_NUM_25;

static QueueHandle_t gQueue;

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 = 5012;
		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);
	}
}

• mode
  • we set the driver as a master (controlling the bus), a transmitter (because we transfer data to the recipients), and configure it to use the built-in 8-bit DAC (because the Odroid Go board does not have an external DAC).
• sample_rate
  • 5012, , , . , , . -, 2500 .
• bits_per_sample
  • , ESP32 8-, I2S , 16 , 8 .
• communication_format
  • , , - , 8- 16- .
• channel_format
  • GPIO, IN+ — IO26, «» I2S. , I2S , IO25, , .
• dma_buf_count dma_buf_len
  • DMA- ( ) , , , IDF. , .

Play sound

void Odroid_PlayAudio(uint16_t* buffer, size_t length)
{
	QueueData data = {};

	data.buffer = buffer;
	data.length = length;

	xQueueSendToBack(gQueue, &data, portMAX_DELAY);
}

Demo

// 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);
    }
}

int lastState = 0;

for (;;)
{
	[...]

	int thisState = input.volume;

	if ((thisState == 1) && (thisState != lastState))
	{
		Odroid_PlayAudio(soundBuffer, soundEffectLength*2);
	}

	lastState = thisState;

	[...]
}

Source

References

• Odroid go schematic
• Audio Amplifier Datasheet
• ESP-IDF Documentation: DAC
• ESP-IDF Documentation: I2S
• WAVE File Format
• Video: Bit Depth Explanation
• Video: Sample Rate Explanation