STM32G0 - G0B1RE GPIO MOD REGISTER not enabled

[dx7]

Hi, I use STM32Cube IDE, and use STM32G0 - G0B1RE device. I try to enable the mod register to blink the LED here is the code that i try so far, based on the Reference Manual (rm0444), I need to enable RCC_IOPENR before modify the GPIOx_MODER. But unfortunately it still did not work.

When i try in debugging mode via the SFRs by set the value of RCC_IOPENR, GPIOA MODER (MODER5), OTYPER (OT5), PUPDR PUPDR(5), and BSRR the LED was turned on. 

The LED is at GPIOA (PA5) based on the schematic.

Did i missed something? or there is anything to enable before I modifie the GPIOx_MODER?

In the reference manual to enable to peripheral in STMG0-G0B1RE the GPIO Bus is IOPORT not AHB or APB 

#include "main.h"
#include "stdint.h"

int main(void)
{
  uint32_t *ptr;
  
  // RCC_IOPENR
  ptr = (uint32_t *)(0x40021000 + 0x34);
  *ptr |= (0x1 << 0); //set bit position 0 to value 1 (0x1) for GPIOA

  // GPIO MOD Register GPIOA
  // [ISSUE] THE MOD REGISTER VALUE DID NOT CHANGE
  ptr = (uint32_t *)0x50000000;
  *ptr |= (0x1 << 10);

  //OTYPE
  ptr++;
  *ptr &= ~(uint32_t)(0x1 << 5); //output type

  //PUPDR
  ptr++;
  *ptr |= (uint32_t)(0x2 << 10); //pull down

  ptr++;
  *ptr |= (0x1 << 5);//turn on led
  *ptr |= (0x1 << 21);// turn off led

}

[TDK · Accepted solution]

A few things:

The default value for MODE0 is 0b11, so setting bit 0 will not change anything since it's already set. That is expected. You should to unset bit 1 (not done) and set bit 0 (already set).

Using the CMSIS defines will make your code much more readable. For example:

GPIOA->MODER = (GPIOA->MODER & ~0x03) | 0x01;

Mark the register as volatile to prevent the compiler from optimizing out changes that otherwise have no effect.

volatile uint32_t *ptr;

[dx7]

Thank you for your response, but still did not work, when i try with HAL it works, but manually do from the registers it did not work, there something that keep the GPIOx_MODER value not change

        RCC->IOPENR = (0x1 << 0);

	GPIOA->MODER = (GPIOA->MODER & ~0x03) | 0x01;

	GPIOA->OTYPER = (0x0 << 10);

	GPIOA->PUPDR = (0x02 << 10);

	GPIOA->BSRR = (0x1 << 5);
	GPIOA->BSRR = (0x1 << 21);

this is the memory value for 0x50000000 (GPIOA Register)

[dx7]

Finally did it, thanks to @TDK for suggestion, i will accept your solution.

Here is the working code:

RCC->IOPENR = (0x1 << 0);

GPIOA->MODER = (GPIOA->MODER & ~GPIO_MODER_MODE5_1)| 0x1; //or ~0x00000800

GPIOA->OTYPER = (0x0 << 10);

GPIOA->PUPDR = (0x02 << 10);

GPIOA->BSRR = (0x1 << 5);
GPIOA->BSRR = (0x1 << 21);

GPIOA->BSRR = (0x1 << 5);
GPIOA->BSRR = (0x1 << 21);

[TDK]

Sorry, thought you were setting up PA0, not PA5. But the rationale was correct. Glad you got it working.