3 Replies Latest reply on Nov 29, 2016 3:27 AM by bob.marlowe

Initial startup configuration of I/Os

anands Aug 18, 2017 3:01 PM

Hi,

I am using CY8C4245 (Psoc4),and configured GPIOs as outputs and controlling them in application.

I am seeing the the IOs are going high during power up in my contoller. The Psoc3 and Psoc5 has the option of controlling the IOs during startup through nonvolatile latches (NVLs) but in Psoc4 seems to be diffucult ... ?

Is there any possibility to control (before init ) these during power up state..?

little help would be appreciated

Thanks,

Anand

1. Re: Initial startup configuration of I/Os

bob.marlowe Nov 29, 2016 2:13 AM (in response to anands)
Welcome in the forum, Anand.

There are 3 stages for PSoC4 GPIO pins during power-up:


Until the minimum voltage reached (1.8V) the outputs are undefined.

Outputs go High-Z until programmed during boot

Outputs follow the programming


To keep the pins to a defined state during the High-Z phase you will need some resistors to force the states to whatever you want.



Bob
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2. Re: Initial startup configuration of I/Os

anands Nov 29, 2016 3:02 AM (in response to anands)

Thank You Bob,

But when checked the data sheet the reset option tab for GPIO pin is only applicable for PSoC 3 and PSoC5, and I am using PSoC4, Is there any other way to configure it.
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3. Re: Initial startup configuration of I/Os

bob.marlowe Nov 29, 2016 3:27 AM (in response to anands)

No option for PSoC4, use resistors.

Bob
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