LPC11u68 Expresso Board Hold Pin Low During Power Up

dustinhagstrom — Tue, 05 Dec 2017 20:14:12 GMT

Hello all,

I have an LPC11u68 LpcExpresso board and I have uploaded the attached cpp file (via creating a new project and verifying it runs correctly). My program wishes to hold a pin low even through power cycles of the LPC board. As you can see from the attached sketch I have put a pulldown via pin muxing on pin 1_18 and I tell the system to make it output low.

The problem is, when I power up the board there is a very brief period where the pin goes high just as the power goes high, then the pin goes low as it should. Is there a way to keep that pin low even during power application to the board? It is a requirement for a project I am working on.

In the attached scope shot, the (Yellow) Channel 1 is pin 1_18 and the (Blue) Channel 2 is the 3.3V line to show when power is applied.

Thank you for your help,

Dustin

Re: LPC11u68 Expresso Board Hold Pin Low During Power Up

jeremyzhou — Fri, 08 Dec 2017 02:48:37 GMT

Hi Dustin Hagstrom,

To update this case, please reply to this email.

Thank you for your interest in NXP Semiconductor products and 

for the opportunity to serve you.

It's no way to modify the default state of pin: pull-up enabled before execute the corresponding instruction.

Hope this is clear.

TIC

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LPC MicrocontrollersのトピックRe: LPC11u68 Expresso Board Hold Pin Low During Power Up

LPC11u68 Expresso Board Hold Pin Low During Power Up

Re: LPC11u68 Expresso Board Hold Pin Low During Power Up