Greetings,
I am trying to blink LED using baremetal programming. I am just starting bare metal programming. My LED on Nucleo - F070 board is not being turned ON.
I checked register values on data sheet and user manual and it seems to be correct. RCC and GPIOA are in different bus and I was confused a bit. I have mentioned the code below.
Kindly, help me getting through this. Thank you so much in advance.
// Where is the LED connected
// Port - A
// Pin - 5
#define PERIPH_BASE (0x40000000UL) // Base addr. of peripheral in memory
#define OFFSET_AHB2PERIPH (0x08000000UL) // In bus AHB2 0x4800 0000 is the address of GPIO port A & this offset + base value = GPIOA PORT A in memory
#define AHB2_PERIPHBASE (PERIPH_BASE+OFFSET_AHB2PERIPH) // 0x4800 0000 is starting point of AHB2
#define GPIOA_OFFSET (0x00000000UL)
#define GPIOA_BASE (AHB2_PERIPHBASE+GPIOA_OFFSET)
#define AHB1_PERIPHBASE (0x40020000UL)
#define RCC_OFFSET (0x00001000UL) //0x4002 1000 is the starting addr.
#define RCC_BASE (*(volatile unsigned int *)(AHB1_PERIPHBASE+RCC_OFFSET)) // starting addr. of RCC
#define AHBEN_REG_OFFSET (0x14UL) // offset to be added in RCC base according to Ref. Manual 7.4.6
#define RCC_AHBEN_REG (*(volatile unsigned int *)(RCC_BASE+AHBEN_REG_OFFSET))
#define GPIOA_EN (1UL<<17) // As per Ref. Manual 7.4.6 moving 1 to bit 17 to enable GPIOA
/*1<<0 = 0000 0000 0000 0000 0000 0000 0000 0001
* 1<< 4 = 0000 0000 0000 0000 0000 0000 0001 0000 */
#define GPIOA_MODE_REG_OFFSET (0x0000UL)
#define GPIOA_MODE_REG (*(volatile unsigned int *)(GPIOA_BASE+GPIOA_MODE_REG_OFFSET))
/*As we are using PA5 - we will be using MODER[1:0] - bit 11 & bit 10*/
/*
*
* 00 -> INPUT MODE
* 01 -> General Purpose output mode
* 10 -> Alternate function mode
* 11 -> Analog mode
*
* */
/*To set bit 10 to 1 = (1UL<<10)
* To set bit 11 to 0 &=~(1UL<<11)*/ // according to Ref. MAnual
#define GPIOA_OD_R (0x14UL) // Offset for output data register
#define GPIOA_OD_REG (GPIOA_BASE+GPIOA_OD_R) // Using OUTPUT register as we have set GPIOA-5 as an output pin
#define PIN5 (1UL<<5) // To toggle pin 5 we need to toggle 5th bit in GPIOA_ODR register
#define LED_PIN PIN5
int main(void)
{
//1. Enable clock access to GPIO
RCC_AHBEN_REG != GPIOA_EN; // "!=" operation is done to prevent any other bit to change as "=" operation may disrupt other bits for the operation
//2. Set PA5 as an output pin
GPIOA_MODE_REG != (1UL<<10);
GPIOA_MODE_REG &=~(1UL<<11);
while(1)
{
GPIOA_OD_REG != PIN5;
} // End of while loop
} // end of the main function
