/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2025 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

#define DISPLAY_RS  ((uint16_t) (0x1U << 7))
#define DISPLAY_RW  ((uint16_t) (0x1U << 10))
#define DISPLAY_ENA ((uint16_t) (0x1U << 11))

#define PANIC(status)        \
	do {                     \
		GPIOD->ODR = status; \
		while (1) {}         \
	} while (0)

#define POLL_UNTIL_READY do { while (read_status() & 0x80) {} } while (0)

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

int change = 1;

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

uint8_t read_status(void)
{
	// make sure GPIOE is in correct mode
	GPIOE->MODER = 0x00504000;

	if (GPIOE->MODER != 0x00504000)
		PANIC(0x4000);

	uint8_t status = 0;

	GPIOE->ODR = 0x0;
	GPIOE->BSRR = DISPLAY_RW;

	GPIOE->BSRR = DISPLAY_ENA;
	status |= (GPIOE->IDR & 0xF000) >> 8;
	GPIOE->BSRR = (DISPLAY_ENA << 16);

	GPIOE->BSRR = DISPLAY_ENA;
	status |= (GPIOE->IDR & 0xF000) >> 12;
	GPIOE->BSRR = (DISPLAY_ENA << 16);

	GPIOE->ODR = 0x0;

	return status;
}

void write_instruction_byte(uint8_t code)
{
	POLL_UNTIL_READY;

	// make sure GPIOE is in correct mode
	GPIOE->MODER = 0x55504000;

	if (GPIOE->MODER != 0x55504000)
		PANIC(0x4000);

	GPIOE->ODR = (code & 0xF0) << 8;
	GPIOE->BSRR = DISPLAY_ENA;
	GPIOE->BSRR = (DISPLAY_ENA << 16);

	GPIOE->ODR = (code & 0x0F) << 12;
	GPIOE->BSRR = DISPLAY_ENA;
	GPIOE->BSRR = (DISPLAY_ENA << 16);
}

void write_data_byte(uint8_t code)
{
	POLL_UNTIL_READY;

	// make sure GPIOE is in correct mode
	GPIOE->MODER = 0x55504000;

	if (GPIOE->MODER != 0x55504000)
		PANIC(0x4000);

	GPIOE->ODR = ((code & 0xF0) << 8) | (DISPLAY_RS);
	GPIOE->BSRR = DISPLAY_ENA;
	GPIOE->BSRR = DISPLAY_ENA << 16;

	GPIOE->ODR = ((code & 0x0F) << 12) | (DISPLAY_RS);
	GPIOE->BSRR = DISPLAY_ENA;
	GPIOE->BSRR = DISPLAY_ENA << 16;
}

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  /* USER CODE BEGIN 2 */

  GPIOD->ODR = 0xF000;

  // switch to 4-bit 2-line mode
  write_instruction_byte(0x28);

  // reset display
  write_instruction_byte(0x01);

  // enable display
  write_instruction_byte(0x0C);

  // move cursor to first line
  write_instruction_byte(0x80);

  // write string
  char a[] = "Well, hi there!";
  for (int i = 0; i < sizeof(a)-1; i++) {
	  write_data_byte(a[i]);
  }

  /*
  // move cursor to second line
  write_instruction_byte(0xC0);
  while (read_status() & 0x80) {}

  // write another string
  char b[] = "I'm doing it!";
  for (int i = 0; i < sizeof(b)-1; i++) {
	  write_data_byte(b[i]);
	  while (read_status() & 0x80) {}
  }
  */

  GPIOD->ODR = 0x0000;

  unsigned int counter = 0;
  write_instruction_byte(0x04); // set address decrement after write

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
	counter += change;
	counter &= 0xFFFF;

	unsigned int c = counter;

	write_instruction_byte(0xC4);

	for (int i = 0; i < 5; i++) {
		int current_digit = c % 10;
		c /= 10;

		write_data_byte('0' + (char) current_digit);
	}

	HAL_Delay(70);
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Configure the main internal regulator output voltage
  */
  __HAL_RCC_PWR_CLK_ENABLE();
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  /** 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};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOE_CLK_ENABLE();
  __HAL_RCC_GPIOD_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOE, GPIO_PIN_7|GPIO_PIN_10|GPIO_PIN_11|GPIO_PIN_12
                          |GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15, GPIO_PIN_RESET);

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOD, GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15, GPIO_PIN_RESET);

  /*Configure GPIO pin : PA0 */
  GPIO_InitStruct.Pin = GPIO_PIN_0;
  GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  /*Configure GPIO pins : PE7 PE10 PE11 PE12
                           PE13 PE14 PE15 */
  GPIO_InitStruct.Pin = GPIO_PIN_7|GPIO_PIN_10|GPIO_PIN_11|GPIO_PIN_12
                          |GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOE, &GPIO_InitStruct);

  /*Configure GPIO pins : PD12 PD13 PD14 PD15 */
  GPIO_InitStruct.Pin = GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);

  /* EXTI interrupt init*/
  HAL_NVIC_SetPriority(EXTI0_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(EXTI0_IRQn);

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* 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 */