STM32F103C8T6 Blue Pill And Character LCD Interfacing In 8-Bit Mode Example

In this ARM programming example, I will use an earlier day character LCD to show text. This character LCD conventionally uses an HD44780 LCD controller manufactured by Hitachi. Currently there are a lot of low cost equivalent LCD controllers.

Blue Pill Experiment On Bread Board

I will not write the details about this controller here because it's already explained in previous tutorial. But it uses the ATMega32 AVR micro-controller. 

Blue Pill Simulating Program Using Proteus VSM 8.15

I use the lower nibble of Port A to send command or data to LCD module. PortA is a 16-bit bi-directional I/O. PC14 connects to LCD Register Select (RS) while PC15 connects to LCD En (Enable). As we just needs to send data or command to LCD module, the LCD Read/Write (R/W) just connect to GND.

GPIO Setting In Device Configuration Tool

Without writing a legacy style C/C++ for ARM micro-controller, I use the Code Configuration Tool inside the STM32CubeIDE. It will generate C/C++ source code whenever we have finish all preferred setting on target MCU. 

SYS Setting

In SYS tab, I select Serial Wire as the debug interface with ST-LINK V2. The System Wake-Up check box must left unchecked to enable the PA0 as general purpose I/O.

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2023 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
 
#include "main.h"
 
void delay(uint16_t num){
	for(uint16_t i=0;i<num;i++);
}
 
void lcdCommand(uint16_t cmd){
	GPIOA->ODR=cmd;
	//GPIOB->ODR&=~(1<<RS_Pin);
	HAL_GPIO_WritePin(RS_GPIO_Port,RS_Pin,GPIO_PIN_RESET);
	//GPIOB->ODR|=(1<<EN_Pin);
	HAL_GPIO_WritePin(EN_GPIO_Port,EN_Pin,GPIO_PIN_SET);
	//HAL_Delay(1);
	delay(100);
	//GPIOB->ODR&=~(1<<EN_Pin);
	HAL_GPIO_WritePin(EN_GPIO_Port,EN_Pin,GPIO_PIN_RESET);
	//HAL_Delay(10);
	delay(10000);
}
 
void lcdData(uint8_t data){
	GPIOA->ODR=data;
	//GPIOB->ODR|=(1<<RS_Pin);
	HAL_GPIO_WritePin(RS_GPIO_Port,RS_Pin,GPIO_PIN_SET);
	//GPIOB->ODR|=(1<<EN_Pin);
	HAL_GPIO_WritePin(EN_GPIO_Port,EN_Pin,GPIO_PIN_SET);
	//HAL_Delay(1);
	delay(10);
	//GPIOB->ODR&=~(1<<EN_Pin);
	HAL_GPIO_WritePin(EN_GPIO_Port,EN_Pin,GPIO_PIN_RESET);
	//HAL_Delay(10);
	delay(1000);
}
 
void lcdInit(void){
	//GPIOB->ODR&=~(1<<RS_Pin);
	HAL_GPIO_WritePin(EN_GPIO_Port,EN_Pin,GPIO_PIN_RESET);
	//HAL_Delay(2);
	delay(20000);
	lcdCommand(0x38);
	lcdCommand(0x0F);
	lcdCommand(0x01);
	//HAL_Delay(20);
	delay(20000);
	lcdCommand(0x06);
}
 
void lcdGotoXy(unsigned char x,unsigned char y){
	unsigned char charAddr[]={0x80,0xC0,0x94,0xD4};
	lcdCommand(charAddr[y-1]+x-1);
	//HAL_Delay(1);
	delay(1000);
}
 
void lcdPrint(char *str){
	unsigned char i=0;
	while(str[i]!=0){
		lcdData(str[i]);
		i++;
	}
}
 
void lcdClear(void){
	lcdCommand(0x01);
	delay(100);
}
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
 
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
  /* Configure the system clock */
  SystemClock_Config();
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
 
  lcdInit();
  lcdGotoXy(3,1);
  lcdPrint("STM32F103C8T6");
  lcdGotoXy(1,2);
  lcdPrint("Blue Pill Module");
  for(uint8_t i=0;i<200;i++) delay(50000);
  lcdClear();
  lcdGotoXy(1,1);
  lcdPrint("LCD Programming");
  lcdGotoXy(3,2);
  lcdPrint("STM32CubeIDE");
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
 
  }
  /* USER CODE END 3 */
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
 
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
 
  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOC, RS_Pin|EN_Pin, GPIO_PIN_RESET);
 
  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3
                          |GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7, GPIO_PIN_RESET);
 
  /*Configure GPIO pins : RS_Pin EN_Pin */
  GPIO_InitStruct.Pin = RS_Pin|EN_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
 
  /*Configure GPIO pins : PA0 PA1 PA2 PA3
                           PA4 PA5 PA6 PA7 */
  GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3
                          |GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
 
/* USER CODE END 4 */
 
/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}
 
#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
 

I use its internal HSI RC clock source. However this module has an external 8MHz crystal oscillator. Click here to download its source file.

Clock Configuration

I re-arrange the Blue Pill model in Proteus VSM 8.15. I want to make its pin map similar to the physical hardware.

Schematic Diagram

 

Top View #1

Top View #2

However it can simulate like the original model. The STM32 Blue Pill supply voltage is +3.3V while the LCD module supply voltage is +5V. The USB power bus gives the module a stable +5V DC voltage. I use another micro USB cable connects to the USB header on the STM32 Blue Pill module.

Using A +3.3V Supply Voltage For The LCD Module

However we can connect these modules to +5.0V supply voltage from the ST-LINK V2 debugger. As shown in the picture above, using a +3.3V supply for LCD module causing an insufficient power that make the display data unclear.