QN908x GPIO PA14 voltage level

[ankur_rathi]

Hi,

I am using PA14 as a GPIO output pin.
When, I am trying to make it low, it is not going till 0V, but to 2.0V.
At high, the voltage is 3.3V but at low, voltage is 2.0V instead of 0V..

But, with the same configurations, I am able to make other GPIOs to go till 0V.
In the specs also, I am not able to get anything which specify this behavior wrt PA14.

Is there something I am missing here?

[stephanie_m]

Hello, 

Are you using some kind of demo/example for this? Are you sure that the pin it's not being used for another functionality in another part of the code? Is it your custom board? Are you using the Development kit? 

Regards ,

Estephania 

[ankur_rathi]

Hi Estephania,
I am using QN908x Development board.
I am using "GPIO Led output Example" code.
I have modified one LED pin which is connected to PA13 to PA14 for our testing purpose.
We found that on GPIO PA14, the voltage level toggles between 3.3V to 2.0V instead of 3.3V to 0V(This by probing the GPIO PA14 on CRO).
 GPIO PA14 is configured as GPIO only. I have tried different Drive settings(Pull Up/Down) also and there is no change in the output.

In GPIO led output example code, FlexComm0 Rx and Tx pins are used.
PA14 is also capable of RTS, but we have not initialized this as FlexComm, PA14 is configured as GPIO.

We tested above scenario on PA15, which is able to toggle between 3.3V to 0V.

[kishansaralaya]

Is it a bug in the QN908x? I also observed same behavior. Can we get more clarification from NXP technical team.

[stephanie_m · Accepted solution]

Hello, 

If you check the schematic of the board you are using, you can track down that the pins are connected to a dual supply translating transceiver and that goes to the gyroscope in the board which might be the reason why you are seeing such a change in the current. 

Do you have the jumper places in the JP11? DO you have the same measurements if you remove the jumper? 

[ankur_rathi]

Thanks Estephania for pointing out that.
The proper switching of voltage takes places after removing JP11.