topic Re: GPIO read pin issue in LPC Microcontrollers

GPIO read pin issue

ketulpatel — Mon, 22 Nov 2021 08:50:30 GMT

Hello,

I'm using LPC1833. And set pin PB_0 ( GPIO5[20] ) as an output pin.
But when I read it using the PIN register, It showing 0 state even I set it to 1.

Thanks,
Ketul

Re: GPIO read pin issue

ZhangJennie — Wed, 24 Nov 2021 09:52:07 GMT

You set the GPIO as output but you want to read it. Why do you operate IO in this way?

If you need to read pin state, please switch the IO setting as input then read it.

Re: GPIO read pin issue

ketulpatel — Wed, 24 Nov 2021 13:24:43 GMT

Hello @ZhangJennie, thanks for the response,

Still getting 0 value, following steps are followed:

1. Pin Mux:
Pin name - PB_0 with GPIO5[20]
Mode - (0x2 << 3) //Enable Pull-up resistor
2. Set direction (DIR register) = Output
3. Set value (SET register)
4. Set direction (DIR register) = Input
5. Read Pin state (PIN register) = getting 0 value
6. Set direction (DIR register) = Output

Thanks,
Ketul

Re: GPIO read pin issue

ZhangJennie — Fri, 26 Nov 2021 09:28:43 GMT

Can you please measure PB_0 with multimeter, what's the voltage ?

Re: GPIO read pin issue

Kushal_Panchal — Wed, 13 Nov 2024 10:12:01 GMT

Hi,

Make sure Input buffer enable[bit 6]. The input buffer is disabled by default at reset and must be enabled for receiving.

Thanks,

Kushal