topic Re: Using on board switch on Xpresso V2 board for LPC11U37H in LPC Microcontrollers

Using on board switch on Xpresso V2 board for LPC11U37H

ojaskulkarni — Fri, 28 Oct 2016 02:37:12 GMT

Hello,

I am using NXP Xpresso V2 board for LPC11U37H. I am trying to blink on board LED's by reading SW1 and SW2. To sense SW1 and SW2, I am using API library functions, Board_Buttons_Init(), ButtonsGetStatus().

With this I am able to sense SW2 properly but SW1 is always pressed detected. My question is, because SW1 is connected to WAKEUP pin and supplying external voltage, do I need to initialize this GPIO in different manner as of GPIO of SW2 ? Is this triggering SW1 to detect always pressed?

Original Attachment has been moved to: board.c.zip

Re: Using on board switch on Xpresso V2 board for LPC11U37H

DavidS — Fri, 28 Oct 2016 22:43:40 GMT

Hi Ojas,

Check your RV2 setting. If it is shorting to ground your signal will not ever be high (deasserted).

If it is set so PIO0_16-ADC_5-WAKEUP is high, I think it should work (I don’t have a board but looked at schematic).

Regards,

David

Re: Using on board switch on Xpresso V2 board for LPC11U37H

pavelhudecek — Sat, 29 Oct 2016 01:31:18 GMT

Hi,

enable internal pull-up for this pin or connect it via resistor 1-100 kOhm to 3.3 V.

Re: Using on board switch on Xpresso V2 board for LPC11U37H

ojaskulkarni — Sun, 30 Oct 2016 16:23:02 GMT

Hi David,

Good observation, I checked for RV2 but it is not shorted to ground. Looks like have some other issue.

Regards,

Ojas

Re: Using on board switch on Xpresso V2 board for LPC11U37H

ojaskulkarni — Sun, 30 Oct 2016 16:25:04 GMT

Hi Pavel,

I tried by activating internal pull up for that pin but still detecting as switch is pressed.

Regards,

Ojas

Re: Using on board switch on Xpresso V2 board for LPC11U37H

pavelhudecek — Sun, 30 Oct 2016 17:25:17 GMT

I'm sorry, I mistook SW1 with SW2. SW1 have pull-up R73 and not need internal.
:-)

Re: Using on board switch on Xpresso V2 board for LPC11U37H

pavelhudecek — Sun, 30 Oct 2016 17:46:36 GMT

This is probably the right direction. You must set the trimmer to majority from the 3.3 V.
Attention: At 100%, or very close to 100% SW1 cannot able to decrease voltage bellow threshold, because R66 prevents it.

(I do not know if I wrote it correctly in English)