Part 3: Display

CMakeLists.txt

@@ -3,6 +3,7 @@ cmake_minimum_required(VERSION 3.5)
 set(EXTRA_COMPONENT_DIRS "src")
 set(COMPONENTS "esptool_py src")
 
+
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 
 project(game)

src/CMakeLists.txt

@@ -1,5 +1,12 @@
 idf_component_register(
-	SRCS "main.c"
-	INCLUDE_DIRS ""
-	PRIV_REQUIRES "")
+	SRCS
+	"main.c"
+	"odroid/display.c"
+	"odroid/input.c"
+
+	INCLUDE_DIRS
+	"."
+
+	PRIV_REQUIRES
+	"esp_adc_cal")
 

src/macros.h

@@ -0,0 +1,21 @@
+#pragma once
+
+
+// Counts the number of elements in an array
+#define ARRAY_COUNT(value) ( sizeof(value) / sizeof(value[0]) )
+
+// Swaps the endianness of a 16-bit value
+#define SWAP_ENDIAN_16(value) ( (((value) & 0xFFu) << 8u) | ((value) >> 8u)  )
+
+// Constructs a 16-bit color value of the form RGB565 with proper ESP32 endianness
+#define RGB565(red, green, blue) ( (((red) >> 3u) << 11u) | (((green) >> 2u) << 5u) | ((blue) >> 3u) )
+
+// Converts bytes to bits
+#define BYTES_TO_BITS(value) ( (value) * 8 )
+
+// Extracts the upper byte of a 16-bit value
+#define UPPER_BYTE_16(value) ( (value) >> 8u )
+
+// Extracts the lower byte of a 16-bit value
+#define LOWER_BYTE_16(value) ( (value) & 0xFFu )
+

src/main.c

@@ -1,30 +1,53 @@
+#include "odroid/display.h"
 #include "odroid/input.h"
+#include "macros.h"
 #include <esp_log.h>
 #include <freertos/FreeRTOS.h>
 #include <freertos/task.h>
+#include <string.h>
 
 
 static const char* LOG_TAG = "Main";
-
+static uint16_t gFramebuffer[LCD_WIDTH * LCD_HEIGHT];
 
 void app_main(void)
 {
 	Odroid_InitializeInput();
+	Odroid_InitializeDisplay();
 
 	ESP_LOGI(LOG_TAG, "Odroid initialization complete - entering main loop");
 
+	int x = 0;
+	int y = 0;
+
+	uint16_t color = 0xffff;
+
 	for (;;)
 	{
+		memset(gFramebuffer, 0, 320 * 240 * 2);
+
 		Odroid_Input input = Odroid_PollInput();
 
-		printf(
-			"\ra: %d  b: %d  start: %d  select: %d  vol: %d  menu: %d  up: %d  down: %d  left: %d  right: %d  ",
-			input.a, input.b, input.start, input.select, input.volume, input.menu,
-			input.up, input.down, input.left, input.right);
+		if (input.left) { x -= 20; }
+		else if (input.right) { x += 20; }
 
-		fflush(stdout);
+		if (input.up) { y -= 20; }
+		else if (input.down) { y += 20; }
 
-		vTaskDelay(250 / portTICK_PERIOD_MS);
+		if (input.a) { color = SWAP_ENDIAN_16(RGB565(0xff, 0, 0)); }
+		else if (input.b) { color = SWAP_ENDIAN_16(RGB565(0, 0xff, 0)); }
+		else if (input.start) { color = SWAP_ENDIAN_16(RGB565(0, 0, 0xff)); }
+		else if (input.select) { color = SWAP_ENDIAN_16(RGB565(0xff, 0xff, 0xff)); }
+
+		for (int row = y; row < y + 50; ++row)
+		{
+			for (int col = x; col < x + 50; ++col)
+			{
+				gFramebuffer[LCD_WIDTH * row + col] = color;
+			}
+		}
+
+		Odroid_DrawFrame(gFramebuffer);
 	}
 
 	// Should never get here

src/odroid/display.c

@@ -0,0 +1,184 @@
+#include "display.h"
+#include "macros.h"
+#include <driver/gpio.h>
+#include <driver/spi_master.h>
+#include <esp_log.h>
+
+
+static const char* LOG_TAG = "OdroidDisplay";
+
+static const gpio_num_t LCD_PIN_MISO = GPIO_NUM_19;
+static const gpio_num_t LCD_PIN_MOSI = GPIO_NUM_23;
+static const gpio_num_t LCD_PIN_SCLK = GPIO_NUM_18;
+static const gpio_num_t LCD_PIN_CS = GPIO_NUM_5;
+static const gpio_num_t LCD_PIN_DC = GPIO_NUM_21;
+static const gpio_num_t LCD_PIN_BACKLIGHT = GPIO_NUM_14;
+
+
+typedef enum
+{
+	SOFTWARE_RESET = 0x01u,
+	SLEEP_OUT = 0x11u,
+	DISPLAY_ON = 0x29u,
+	COLUMN_ADDRESS_SET = 0x2Au,
+	PAGE_ADDRESS_SET = 0x2Bu,
+	MEMORY_WRITE = 0x2Cu,
+	MEMORY_ACCESS_CONTROL = 0x36u,
+	PIXEL_FORMAT_SET = 0x3Au,
+} CommandCode;
+
+
+typedef struct
+{
+	CommandCode code;
+	uint8_t parameters[15];
+	uint8_t length;
+} StartupCommand;
+
+
+static spi_device_handle_t gSpiHandle;
+
+static StartupCommand gStartupCommands[] =
+{
+	// Reset to defaults
+	{
+		SOFTWARE_RESET,
+		{},
+		0
+	},
+
+	// Landscape Mode
+	// Top-Left Origin
+	// BGR Panel
+	{
+		MEMORY_ACCESS_CONTROL,
+		{0x20 | 0xC0 | 0x08},
+		1
+	},
+
+	// 16 bits per pixel
+	{
+		PIXEL_FORMAT_SET,
+		{0x55},
+		1
+	},
+
+	// Exit sleep mode
+	{
+		SLEEP_OUT,
+		{},
+		0
+	},
+
+	// Turn on the display
+	{
+		DISPLAY_ON,
+		{},
+		0
+	},
+};
+
+
+static
+void SendCommandCode(CommandCode code)
+{
+	spi_transaction_t transaction = {};
+
+	transaction.length = BYTES_TO_BITS(1);
+	transaction.tx_data[0] = (uint8_t)code;
+	transaction.flags = SPI_TRANS_USE_TXDATA;
+
+	gpio_set_level(LCD_PIN_DC, 0);
+	spi_device_transmit(gSpiHandle, &transaction);
+}
+
+static
+void SendCommandParameters(uint8_t* data, int length)
+{
+	spi_transaction_t transaction = {};
+
+	transaction.length = BYTES_TO_BITS(length);
+	transaction.tx_buffer = data;
+	transaction.flags = 0;
+
+	gpio_set_level(LCD_PIN_DC, 1);
+	spi_device_transmit(gSpiHandle, &transaction);
+}
+
+
+void Odroid_InitializeDisplay(void)
+{
+	// Initialize the SPI bus
+	{
+		spi_bus_config_t spiBusConfig = {};
+		spiBusConfig.miso_io_num = LCD_PIN_MISO;
+		spiBusConfig.mosi_io_num = LCD_PIN_MOSI;
+		spiBusConfig.sclk_io_num = LCD_PIN_SCLK;
+		spiBusConfig.quadwp_io_num = -1;
+		spiBusConfig.quadhd_io_num = -1;
+		spiBusConfig.max_transfer_sz = LCD_WIDTH * LCD_HEIGHT * LCD_DEPTH;
+
+		ESP_ERROR_CHECK(spi_bus_initialize(VSPI_HOST, &spiBusConfig, 1));
+
+		ESP_LOGI(LOG_TAG, "Initialized SPI Bus");
+	}
+
+
+	// Add the display device to the SPI bus
+	{
+		spi_device_interface_config_t spiDeviceConfig = {};
+		spiDeviceConfig.clock_speed_hz = SPI_MASTER_FREQ_40M;
+		spiDeviceConfig.spics_io_num = LCD_PIN_CS;
+		spiDeviceConfig.queue_size = 1;
+		spiDeviceConfig.flags = SPI_DEVICE_NO_DUMMY;
+
+		ESP_ERROR_CHECK(spi_bus_add_device(VSPI_HOST, &spiDeviceConfig, &gSpiHandle));
+
+		ESP_LOGI(LOG_TAG, "Added display to SPI bus");
+	}
+
+
+	// Set the DC and backlight pins as outputs
+	{
+		gpio_set_direction(LCD_PIN_DC, GPIO_MODE_OUTPUT);
+		gpio_set_direction(LCD_PIN_BACKLIGHT, GPIO_MODE_OUTPUT);
+	}
+
+
+	// Send the initialization commands to the display
+	{
+		int commandCount = ARRAY_COUNT(gStartupCommands);
+
+		for (int commandIndex = 0; commandIndex < commandCount; ++commandIndex)
+		{
+			StartupCommand* command = &gStartupCommands[commandIndex];
+
+			SendCommandCode(command->code);
+
+			if (command->length > 0)
+			{
+				SendCommandParameters(command->parameters, command->length);
+			}
+		}
+
+		ESP_LOGI(LOG_TAG, "Initialized display");
+	}
+}
+
+void Odroid_DrawFrame(uint16_t* buffer)
+{
+	// Set drawing window width to (0, LCD_WIDTH)
+	uint8_t drawWidth[] = { 0, 0, UPPER_BYTE_16(LCD_WIDTH), LOWER_BYTE_16(LCD_WIDTH) };
+	SendCommandCode(COLUMN_ADDRESS_SET);
+	SendCommandParameters(drawWidth, ARRAY_COUNT(drawWidth));
+
+	// Set drawing window height to (0, LCD_HEIGHT)
+	uint8_t drawHeight[] = { 0, 0, UPPER_BYTE_16(LCD_HEIGHT), LOWER_BYTE_16(LCD_HEIGHT) };
+	SendCommandCode(PAGE_ADDRESS_SET);
+	SendCommandParameters(drawHeight, ARRAY_COUNT(drawHeight));
+
+	// Send the buffer to the display
+	SendCommandCode(MEMORY_WRITE);
+	SendCommandParameters((uint8_t*)buffer, LCD_WIDTH * LCD_HEIGHT * LCD_DEPTH);
+}
+

src/odroid/display.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <stdint.h>
+
+
+#define LCD_WIDTH (320)
+#define LCD_HEIGHT (240)
+#define LCD_DEPTH (2)
+
+
+void Odroid_InitializeDisplay(void);
+void Odroid_DrawFrame(uint16_t* buffer);
+