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Published March 29, 2026

Exploring RT-Spark's (RT-Thread: Spark-1) built-in LCD

The basics of Spark-1's built-in LCD, combined with 5 switches/inputs to alter what is currently shown, including the 3 LEDs.

IntermediateProtip1 hour36

Exploring RT-Spark's (RT-Thread: Spark-1) built-in LCD

Things used in this project

Hardware components

C&K Switches PTS 645 Series Switch

5 Switches to cover "Up, Down, Left, Right, and Center."

Jumper wires (generic)

Consider having at least 20 jumper wires so that you won't have a hard time thinking how to conserve your wires as you connect each component.

LED (generic)

Preferably 3 LEDs, which represents Red, Green Blue, or a single RGB LED. But, This project specifically uses separate 3 separate LEDs, you might get lost in translation if you do not fully know how an RGB LED works.

Breadboard (generic)

Have a breadboard that can hold a lot. It's better to have the big ones so that you won't have a hard time putting the components in a proper place.

Resistor 220 ohm

This 220Ω resistors are used for the 3 LEDs. Though, you can use resistors that are valued around "100Ω-500Ω", or other ranges, provided that you know what you're doing.

Resistor 10k ohm

Optional: Incase you're not using the RT-Spark's (Spark-1) built-in pull-up or pull-down, might as well set the 5 switches/inputs as pull-down to not confuse yourself further.

RT-Spark (Spark-1) RT-Thread Development Boar

The board that we will be using to code the logic, and connect the components.

Software apps and online services

RT-Thread STM32CubeIDE (V1.19.0)

Github: RT-Thread-Studio / SDK-BSP-STM32f407-Spark

Story

T-SPARK (SPARK-1) RT-THREAD DEVELOPMENT BOARD

The RT-Spark, also known as "Spark-1", is a Development board made by RT-Thread, which uses the "STM32F407ZGT6" Microcontroller(MCU). Not only it is embedded with that MCU chip, it also features a few other components, such as Wi-Fi, Buzzer, SD-Card, LED Matrix, and most importantly, the LCD.

For this scenario, the main highlight would be the built-in LCD, which contains 240x240 resolution/pixels that utilizes the Flexible static Memory Controller(FSMC) peripheral communication, then some other implementations, such as 5 momentary switches, and 3 different color LEDs or 1 RGB LED.

BACKLIGHT BUILT-IN LCD

Before proceeding to the upcoming steps, it is recommended to ensure that the built-in LCD is still working or you'll end up sitting for hours and achieve absolutely nothing.

First, create a new STM32 Project, choose the STM32F407ZGT6 MCU, and let the default settings work by itself.

1 / 3 • New STM32 Project

Then, locate the backlight pin to set as an output, generate the CubeMX code, and turn on the pin.

1 / 6 • LCD backlight (LCD_BL)

OUTPUT:

The LCD backlight should light up. Meaning, the backlight is fine, but not yet sure for the LCD.

LCD Backlight Test

CONFIGURING THE PERIPHERAL COMMUNICATION FOR THE BUILT-IN LCD

The built-in LCD uses the ST7789 v3 Driver Chip, and the communication interface is 8080 parallel port, thus the MCU uses the FSMC peripheral communication. To start, we must setup the FSMC to allow us to communicate with the built-in LCD.

First, locate the LCD's reset pin, set it as output, and follow the same steps as we did from the LCD backlight pin.

1 / 3 • LCD Reset (LCD_RST)

Second, configure the FSMC to work with the LCD interface. After that, update/generate the CubeMX Code.

1 / 2 • RT-Spark's (Spark-1) built-in LCD schematic diagram

TWO WAYS TO USE THE LCD

There are two ways to approach when it comes to using the built-in LCD; first, the easy method, which is what this guide is leading to, or the manual approach, from manually turning on the backlight, resetting the configuration, initializing the display, and write data to the screen pixel by pixel.

The code written from the previous instructions was part of the manual configuration of the LCD, specifically for the backlight.

DOWNLOADING BUILT-IN LCD’S HEADER & SOURCE FILES

To avoid doing everything manually, it's essential to download the developers' Software Development Kit(SDK) from the GitHub repository, but that version requires you to have the Real-Time Operating System(RTOS) while this guide uses bare-metal. Therefore, it is recommended to use the Project-Used Libraries if you want a bare-metal approach:

Official - https://github.com/RT-Thread-Studio/sdk-bsp-stm32f407-spark

Project-Used Lib - https://sendgb.com/M8kq5c23FwC

After downloading both the folders “Header, Source Files”, put them into their respective folders from the Project.

Header Files (.h) = ProjectName/Core/Inc

Source Files (.c) = ProjectName/Core/Src

1 / 5 • Header/Inc Files

Lastly, declare the inclusion of the "drv_lcd.h" Header File, and the LCD's functions will now be accessible.

Functions and Definitions

Commonly used functions:

drv_lcd_hw_init() - Turns on backlight, resets and initializes LCD
lcd_clear() - Clears the screen and changes the background color
lcd_show_string() - Allows you to Write character/s or strings
lcd_draw_point() - draws a dot/pixel to the screen
lcd_draw_circle() - draws a circle to the screen
lcd_draw_line() - draws a line to the screen
lcd_draw_rectangle() - draws a rectangle to the screen

List of functions that are listed from the “drv_lcd.h, drv_lcd.c”:

OUTPUT (INCLUDING 5 SWITCHES & 3 LEDS):

If you wish to follow this setup, simply copy the codes, including the pins used below (unless you know what you're doing).

Code

Code

// Code 0:
////////////////////////////////////////////////////////////////////////////////
/* USER CODE BEGIN 0 */
uint8_t switch_Up() { //Used by LCD and REDLED
	return HAL_GPIO_ReadPin(GPIOG, GPIO_PIN_0) == GPIO_PIN_RESET;
}

uint8_t switch_Down() { //Used by LCD and BLUELED
	return HAL_GPIO_ReadPin(GPIOG, GPIO_PIN_1) == GPIO_PIN_RESET;
}

uint8_t switch_Center() { //Used by LCD and GREENLED
	return HAL_GPIO_ReadPin(GPIOG, GPIO_PIN_6) == GPIO_PIN_RESET;
}

uint8_t switch_Left() { //Used solely by LCD
	return HAL_GPIO_ReadPin(GPIOG, GPIO_PIN_2) == GPIO_PIN_RESET;
}

uint8_t switch_Right() { //Used solely by LCD
	return HAL_GPIO_ReadPin(GPIOG, GPIO_PIN_5) == GPIO_PIN_RESET;
}



void RGBLED_Config(uint8_t red, uint8_t green , uint8_t blue) { //leds_set()
	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, !red);
	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, !green);
	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, !blue);
}

void ToggleLEDS() { //light_leds()
	RGBLED_Config(switch_Up(), switch_Center(), switch_Down());
}

void print_switches() {
	if(switch_Up()) {
		lcd_show_string(0, 0, 16, "Button Up is Pressed    ");
	} else if(switch_Down()) {
		lcd_show_string(0, 0, 16, "Button Down is Pressed  ");
	} else if(switch_Left()) {
		lcd_show_string(0, 0, 16, "Button Left is Pressed  ");
	} else if(switch_Right()) {
		lcd_show_string(0, 0, 16, "Button Right is Pressed ");
	} else if(switch_Center()) {
		lcd_show_string(0, 0, 16, "Button Center is Pressed");
	}
}
/* USER CODE END 0 */
////////////////////////////////////////////////////////////////////////////////





//Main:
////////////////////////////////////////////////////////////////////////////////
/* USER CODE BEGIN 2 */
MY_GPIO_Init(); // Your Custom MX_GPIO_Init function to Initialize pins
MY_LEDS_Init(); // Your Custom MY_GPIO_Init function to Initialize built-in LED pins

drv_lcd_hw_init(); // Turns on Back-light, resets the LCD configuration, and initializes the LCD
lcd_clear(BLACK); // Clears everything shown, and changes the background color to white
lcd_set_color(BLACK, WHITE); // Set text color to white, and text background color to black
lcd_show_string(0, 0, 16, "Hello World!"); // Shows "Hello!" to the screen, configured at (x-axis(239max), y-axis(239 max), textsize)
/* USER CODE END 2 */
////////////////////////////////////////////////////////////////////////////////








//Main Loop:
////////////////////////////////////////////////////////////////////////////////
while (1)
{
  /* USER CODE END WHILE */

  /* USER CODE BEGIN 3 */
  print_switches();
  ToggleLEDS();
  HAL_Delay(500);
}
/* USER CODE END 3 */
////////////////////////////////////////////////////////////////////////////////
















//Code 4:
////////////////////////////////////////////////////////////////////////////////
/* USER CODE BEGIN 4 */
void MY_GPIO_Init(void) { //switches_init()
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  
  //__HAL_RCC_GPIOG_CLK_ENABLE(); //Not needed because it is already enable from the MX_GPIO_Init function
  
  // 0 = BtnUp, 1 = BtnDown, 6 = BtnCenter, 2 = BtnLeft, 5 = Right
  GPIO_InitStruct.Pin = GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_6 | GPIO_PIN_2 | GPIO_PIN_5;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(GPIOG, &GPIO_InitStruct);
}
  
void MY_LEDS_Init(void) { //leds_init()
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  
  __HAL_RCC_GPIOA_CLK_ENABLE();
  
  // Set as Active-Low, means it is on at 0V, and off at high volts
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_SET);
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_SET);
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_SET);
  
  // 2 = REDLED, 3 = GREENLED, 0 = BLUELED
  GPIO_InitStruct.Pin = GPIO_PIN_2 | GPIO_PIN_3 | GPIO_PIN_0;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_OD;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
  
  RGBLED_Config(0, 0, 0);
}
/* USER CODE END 4 */
////////////////////////////////////////////////////////////////////////////////

Credits

Kenneth

2 projects • 0 followers

Paul Rodolf P. Castor

16 projects • 9 followers

Exploring RT-Spark's (RT-Thread: Spark-1) built-in LCD