topic Re: LPC81x default state of GPIO in LPC Microcontrollers

LPC81x default state of GPIO

Sid_Zhou — Tue, 03 Jun 2025 05:47:52 GMT

We are using LPC812M101JDH20 on one of our products. The datasheet specified the default state of GPIO(PIO0_16) is "Input with pull-up."

Somehow, in our application, we need this PIO0_16 to be open drain at the very early start-up stage. I am wondering if this default state can be modified somewhere within "startup_LPC8xx.s"

Re: LPC81x default state of GPIO

Harry_Zhang — Wed, 04 Jun 2025 06:43:22 GMT

Hi @Sid_Zhou

You can add related function in SystemInit.

Enable clock to IOCON block.

Configure PIO0_16 as open-drain output.

Harry

Re: LPC81x default state of GPIO

Sid_Zhou — Thu, 05 Jun 2025 01:53:35 GMT

Thanks a lot.
We have around 200us~300us improvement with this solution. This should be enough to solve our problem during start-up.