Nucleo H755 LED3 not turning on (PB14) in IPC Example

[Duc]

Hi everyone,

I am working on a project with the STM32H755ZI-Q (Nucleo H755ZI-Q) board, and I am following this tutorial for Inter-Processor Communication (IPC) using OpenAMP: Link to tutorial.

The setup involves two processors (M4 and M7). Here's the LED behavior that I have implemented:

• LED1 (PB0) is assigned to M4.

• LED2 (PE1) and LED3 (PB14) are assigned to M7.

• When M7 sends a message to M4, M4 replies, and LED1 turns ON.

• If M7 receives the expected message, LED2 turns ON; otherwise, LED3 should turn ON.

The issue:

Everything seems to work fine when LED2 is assigned to M7 (PB14), as it turns ON as expected. However, when I swap the assignments and move LED2 to LED3 (PB14), LED3 doesn’t turn on, despite the message being received and processed correctly.

I have tried putting LED3 in a while loop in the main function and toggling it manually with:

HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_14);

but still, LED3 (PB14) does not turn ON.

Has anyone encountered a similar issue or can suggest where the problem might lie?

Any help would be greatly appreciated!

Thanks in advance!

[TDK]

Ensure it is assigned a core context and is being initialized as a GPIO output.

If in doubt, look at the GPIOB register and ensure MODER bits are as expected.

[Duc]

Hi @TDK,

Thanks for the reminder! Those are things I always keep in mind when working with GPIO initialization and configuration.

[Mike_ST]

Hello,

Share code, ioc file, if you can.

Use a voltmeter to check PB14 output on CN8. Q3 transistor or LD3 LED might be non working.

[Duc]

Hi @Mike_ST ,

I’ve tested my LEDs with the Blinky code, and everything is working fine. Here’s the code I’m using:

[TDK]

  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
	  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_14, GPIO_PIN_SET);
  }

It's probably working as intended but gets changed in the main loop before you can visually notice.

[Duc]

Hi @TDK ,
I initially thought that might be the issue, but after switching to HAL_GPIO_WritePin(), it still didn’t work. I want LED3 to work in the callback function when a message is received by M7 — LED2 works fine there, but LED3 doesn’t. I even tried putting LED3 in a while loop to check if it would work, but it still didn’t in either case.

[TDK]

Remove the code in the main loop where you continuously set the pin state high. That's the issue.

[Duc]

Hi @TDK ,

It seems there was a misunderstanding. The issue I'm currently facing is with LED3. Initially, I had it placed only in the callback, not in the main loop. However, LED3 wouldn't turn on, even when I set the pin state to high. So, I moved it into the main loop to test it further. But even then, when I set the pin state to high, the LED still wouldn't turn on.

To isolate the problem, I created a new project just to blink the LEDs, and in that setup, the LEDs work as expected.

I believe running that code on the Nucleo H755ZI-Q board will provide you with clearer results.

[Duc]

Hi @Mike_ST ,

Do you have any recommendations for addressing this issue?