/**
 ******************************************************************************
 * @file           : main.c
 * @author         : Auto-generated by STM32CubeIDE
 * @brief          : Main program body
 ******************************************************************************
 * @attention
 *
 * Copyright (c) 2026 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.
 *
 ******************************************************************************
 */

#include <stdint.h>
#include "stm32f103xb.h"



#define CAT0_PIN	9
#define CAT1_PIN	10

void display(int num, int dig);
void delay_ms(uint16_t t);

int main(void)
{
	// Enable GPIOA clock
	RCC->APB2ENR |= 1UL << 2;

	// Set PA0-PA6 as 2MHz push-pull output
	GPIOA->CRL = 0x02222222;
	GPIOA->CRH = 0x00000220; // MODEn = 10 (2MHz Output)
	GPIOA->ODR |= 0x0000007F;
	GPIOA->ODR &= ~(1 << CAT0_PIN | 1 << CAT1_PIN); // PA<10:9> = 0

	// Enable GPIOC clock
	RCC->APB2ENR |= 1UL << 4;

	// Set PC13 as 2MHz push-pull output
	GPIOC->CRH &= ~(0x0FUL << 20); // MODE13=00, CNF13=00
	GPIOC->CRH |= 1UL << 21; // MODE13 = 10 (2MHz output)


	// Loop
	int units = 0, dec = 0, tick = 0;
	while ( 1 )
	{
		
		// Seven segment multiplexing
		display(units,0);
		delay_ms(1000); // It should be 1ms in real-time
		display(dec,1);
		delay_ms(1000);	// It should be 1ms in real-time
	
		// Update counters each second
		++units;
			if(units == 10)
			{
				units = 0;
				dec++;
				if(dec==10)
				{
					dec=0;
				}
			}
	}
}




void display(int num, int dig)
{
	// Cathode control (Digit selection)
	GPIOA->ODR &= ~((1 << CAT0_PIN) | (1 << CAT1_PIN));
	if(dig == 0) GPIOA->ODR |= (1 << CAT0_PIN);
	else GPIOA->ODR |= (1 << CAT1_PIN);

	// Display value
	GPIOA->ODR &= ~0x0000007F;
	switch(num)
	{
		case 0: GPIOA->ODR |= (0b1000000); break;
		case 1: GPIOA->ODR |= (0b1111001); break;
		case 2: GPIOA->ODR |= (0b0100100); break;
		case 3: GPIOA->ODR |= (0b0110000); break;
		case 4: GPIOA->ODR |= (0b0011001); break;
		case 5: GPIOA->ODR |= (0b0010010); break;
		case 6: GPIOA->ODR |= (0b0000010); break;
		case 7: GPIOA->ODR |= (0b1111000); break;
		case 8: GPIOA->ODR |= (0b0000000); break;
		case 9: GPIOA->ODR |= (0b0010000); break;
		default: GPIOA->ODR |= (0b1111111); break; // All turn off
	}
}

void delay_ms(uint16_t t) {
	volatile unsigned long l = 0;
	for(uint16_t i = 0; i < t; i++)
	{
		for(l = 0; l < 800; l++);
	}
}