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 (PE1), 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.

 

[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 @Mike_ST ,

Do you have any recommendations for addressing this issue?

[Mike_ST]

Hello,

I'm not sure what is actually the problem,

but based on your zip file, here attached are "main.c" files where I got the RED LED turn on instead of the ORANGE LED when receiving the right message.

[Duc]

Hi @Mike_ST ,

I noticed that in your code, you’ve commented out some sections related to OpenAMP, and surprisingly, everything is working as expected. I’m wondering if something in those functions was preventing me from accessing LED3 with my original code. Could you explain why you decided to comment out that code?

[Mike_ST]

Hello,

if you're talking about the following line:

// MAILBOX_Init();

I noticed it was already called in 

MX_OPENAMP_Init(RPMSG_MASTER, new_service_cb)

So I thouhgt there was no need to call it twice.