Hello there, i tried writing a program that blinks an LED, but for a reason it turns on and stays on, doesn't toggle. I'm using the Discovery board with STM32F407VG MCU.
And this is the code:
Note: I'm connecting pin PA5 with PD12(which is connected to the GREEN LED).
I took this code from a course, where the author uses STM32F411VET mcu, which is a disco board as well. And one strange thing, which he doesn't explain is: he says that "the led" is connected to PA5. I checked the datasheet of the board and don't see any LED connected to that pin.
And btw, he develops this from scratch, write his own structures and registers.
#include <stdint.h> #define PERIPH_BASE 0x40000000U #define AHB1PERIPH_BASE (PERIPH_BASE + 0x00020000U) #define RCC_BASE (AHB1PERIPH_BASE + 0x00003800U) #define GPIOA_BASE AHB1PERIPH_BASE + 0x00U #define __IO volatile //Typecasting: __IO will be used for "volatile" typedef struct{ __IO uint32_t MODER; __IO uint32_t OTYPER; __IO uint32_t OSPEEDR; __IO uint32_t PUPDR; __IO uint32_t IDR; __IO uint32_t ODR; __IO uint32_t BSSR; __IO uint32_t LCKR; __IO uint32_t AFR[2]; //Instead of creating separate members for AFRL and AFRH we create AFR array with size 2 }GPIO_TypeDef; /*This is the list of registers that belong to the GPIO port, regardless of the port you are working with(A...H)*/ /*Next a RCC structure is required, through which we enable AHB or APB*/ typedef struct{ __IO uint32_t CR; __IO uint32_t PLLCFGR; __IO uint32_t CFGR; __IO uint32_t CIR; __IO uint32_t AHB1RSTR; __IO uint32_t AHB2RSTR; __IO uint32_t AHB3RSTR; uint32_t GAP1; //This is 4 bytes long __IO uint32_t APB1RSTR; __IO uint32_t APB2RSTR; uint32_t GAP2[2]; //This is 2 x 4 bytes long => 8 bytes long __IO uint32_t AHB1ENR; __IO uint32_t AHB2ENR; __IO uint32_t AHB3ENR; uint32_t GAP3; //Padding by creating an empty register to reach a certain offset for another register __IO uint32_t APB1ENR; __IO uint32_t APB2ENR; uint32_t GAP4[2]; __IO uint32_t AHB1LPENR; __IO uint32_t AHB2LPENR; __IO uint32_t AHB3LPENR; uint32_t GAP5; __IO uint32_t APB1LPENR; __IO uint32_t APB2LPENR; uint32_t GAP6[2]; __IO uint32_t BDCR; __IO uint32_t CSR; uint32_t GAP7[2]; __IO uint32_t SSCGR; __IO uint32_t PLLI2SCFGR; __IO uint32_t PLLSAICFGR; __IO uint32_t DCKCFGR; }RCC_TypeDef; #define RCC ((RCC_TypeDef *)RCC_BASE) #define GPIOA ((GPIO_TypeDef *)GPIOA_BASE) #define MODER_5_OUT 1<<10 //Set bit 10 in MODER to 1 to set it as output #define LED_PIN 1<<5 int main(void){ RCC->AHB1ENR |= 0x01; //Set bit 3 to 1 GPIOA->MODER |= MODER_5_OUT; while(1){ for(int i=0; i<900000; i++){} //Run a few cycles doing nothing GPIOA->ODR ^= LED_PIN; } }