LPC MicrocontrollersのトピックRe: Using P0[7], P0[8] and P0[9] as digital inputs

Using P0[7], P0[8] and P0[9] as digital inputs

lpcware — Wed, 15 Jun 2016 17:59:28 GMT

Content originally posted in LPCWare by jonas2 on Thu Jun 06 08:18:42 MST 2013
I use an LPC1778 LQFP144</pre>
<pre>I set up the following pins as digital inputs:

P0[7]
P0[8]
P0[9]

I have 3.3 V on the pins but I only read '0's from the PIN register. I've tried to activate the internal pull-up with but the result was the same.
These pins are of type W does this have an impact? I've used type D pins as digital inputs without encountering any problem.

Re: Using P0[7], P0[8] and P0[9] as digital inputs

lpcware — Wed, 15 Jun 2016 17:59:29 GMT

Content originally posted in LPCWare by DF9DQ on Thu Jun 06 13:24:47 MST 2013

This is indeed a specialty of the W type pins.

Have a closer look at the respective IOCON register, with particular attention to bit 7 :-)

Re: Using P0[7], P0[8] and P0[9] as digital inputs

lpcware — Wed, 15 Jun 2016 17:59:30 GMT

Content originally posted in LPCWare by tha on Thu Jun 06 17:30:21 MST 2013

You can try this:

LPC_GPIO0->DIR = 0x0;<span class="Apple-tab-span" style="white-space: pre;"> </span>//set PORT0 as input
LPC_IOCON->P0_7 = 0xA0;
LPC_IOCON->P0_8 = 0xA0;
LPC_IOCON->P0_9 = 0xA0;

Just force the whole port to input and set the pins to the default state (and making sure bit 7 is set). This worked for me. The PIN register was changing value when I force the pins HIGH and LOW.

Re: Using P0[7], P0[8] and P0[9] as digital inputs

lpcware — Wed, 15 Jun 2016 17:59:31 GMT

Content originally posted in LPCWare by jonas2 on Fri Jun 07 00:27:57 MST 2013

You're right, bit 7 if the respective IOCON registers were set to '0'. I set this bit to '1' and now these pins works as expected. Thanks!