Problems with GPIO.

[FRest.1]

I'm working with the NUCLEO-WL55jc1 board and I have one strange behavior. I need one output pin and I've called it Trigger.

Initially, the pin PC2 was used but I wasn't able to make it work. It had incorrect output voltages and some bounce like it was a switch.

Other pins, like LEDs on the board, worked as aspected, so I decided to change the pin with PB1, using the same software: it was working.

In order to investigate, I've used both outputs, the same software, just a set, and a reset after delay. I've connected the oscilloscope to see the output signal reported in the picture.

Tack yellow is the PB1 output (Trigger_pin), track blue is the PC2 output (Test_pin) the wrong one.

 

My simple code.

uint16_t Distance(void) {
 
	uint16_t distanza = 0;
 
	UTIL_LPM_Mode_t lpm_stat = UTIL_LPM_GetMode();
//	UTIL_LPM_S
	APP_LOG(TS_OFF, VLEVEL_H, "\r\n###### ========== PASSO ==========, %d\r\n", lpm_stat);
	BSP_LED_On(LED_BLUE) ;
	HAL_GPIO_WritePin(Trigger_GPIO_Port, Trigger_Pin, GPIO_PIN_SET);
	#ifdef TEST_GPIO
	HAL_GPIO_WritePin(Test_GPIO_Port, Test_Pin, GPIO_PIN_SET);
	#endif
	HAL_Delay(10);
	BSP_LED_Off(LED_BLUE);
	HAL_GPIO_WritePin(Trigger_GPIO_Port, Trigger_Pin, GPIO_PIN_RESET);
	#ifdef TEST_GPIO
	HAL_GPIO_WritePin(Test_GPIO_Port, Test_Pin, GPIO_PIN_RESET);
	#endif
 

Now, PC2 doesn't seem used on the NUCLEO board it's free, so my question: I've done a mistake o there is some sort of bugs on the board?

F.

[FRest.1]

There is activity on PC2, but I'm not able to check what is controlling it.

F.

[TDK]

PC2 is not used per the user manual or the schematic. Recheck wiring, pin/port definitions. Gotta be an answer somewhere. Examine register values.

[Javier1]

Maybe PC2 is declared as open drain? and what you see is the noise of the line being left floating?

[FRest.1 · Accepted solution]

I'm very sorry, I've wasted your time. I've made a mistake counting the PIN on the connector in reverse and wrong order so I was looking at the wrong pin.

What's worse is that I foolishly persevered.

My apologies and thank you for the help, it helped force me to revisit the connections.

F.

[Javier1]

happens to the best of us