topic Re: KEA128 GPIO at 1.4V in Kinetis Microcontrollers

KEA128 GPIO at 1.4V

vigneshbalaji — Tue, 29 Aug 2017 12:19:45 GMT

Hi,

I want to know under what conditions does KEA128 GPIO pins stay at 1.4 volts?

Re: KEA128 GPIO at 1.4V

kerryzhou — Wed, 30 Aug 2017 08:29:58 GMT

Hi VIGNESH BALAJI,

You already ask the same two questions in the case, I post the reply in the case directly.

Please try to add an external pull up in the according pin which you are using, then check the voltage again.
On board output high, then other board configure the pin as GPIO input, take care, don't configure both board 1 and board 2 pin in GPIO output toghether.
You must configure on is GPIO output, another on is GPIO input.
take an example, board 1 output higher, board 2 is the GPIO input.
Add an external 10K pull up resistor between the board 1 and board 2, then test the voltage again, whether you still get 1.5V or you can get 3.3V.
Please test it at first.
Any updated information, please let me know!

Have a great day,
Kerry

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Re: KEA128 GPIO at 1.4V

vigneshbalaji — Wed, 30 Aug 2017 11:28:50 GMT

Hi Kerry,

Can you tell me the reason why i should add a 10K pull up inbetween output of board 1 and input of board 2. I want to configure software wise whether to pull up input of board 1 or pull down input of board 1.

Re: KEA128 GPIO at 1.4V

kerryzhou — Thu, 31 Aug 2017 03:13:56 GMT

Hi VIGNESH BALAJI,

Do you try my suggestions?
And I don't know, whether you enable the internal pull up.
If you already enable the internal pull up, I think the problem is caused by the weak internal pull up resistor.
If you don't enable the internal pull up before, you also can try to enable the internal pull up resistor in PORT_PUEn register.
Please try it on your side, whether it works or not?
If it works, your problem is caused by the weak pull up or no pull up, the pin can't be pull to VDD because no pull up resistor.

Wish it helps you!

Have a great day,
Kerry