Odd GPIO behavior

lpcware — Wed, 15 Jun 2016 17:02:48 GMT

Content originally posted in LPCWare by jdurand on Sat Sep 08 17:35:33 MST 2012
I've done several LPC boards already (LPC1113, LPC1754, LPC4350) and never had a problem with the GPIO...until now.

I have an LPC1226FBD48/301 part on my board here and while I can run code on it (FreeRTOS is running one task at the moment), I can't seem to talk to the GPIO.

For example, I go through and configure some of the IOCON bits for GPIO0 and then try to write to the DIR and OUT registers. No matter what I write the registers read back as 0. I tried using the Peripheral tab of the Code Red debugger and when I try to change the port in that, it warns me for example that it read back 0 after I wrote a 1.

Is there a power or clock I have to enable for the GPIO? I've been looking through the manual but haven't found anything.

Re: Odd GPIO behavior

lpcware — Wed, 15 Jun 2016 17:02:49 GMT

Content originally posted in LPCWare by jdurand on Sat Sep 08 22:06:26 MST 2012
I found it!

In SystemINIT() in CMSIS they have this section

/* System clock to the IOCON needs to be enabled or
most of the I/O related peripherals won't work. */
LPC_SYSCON->SYSAHBCLKCTRL = 0x0001001FUL;

The problem is, it's turning OFF most clocks that were on by default. All I had to do was turn them back on again.

topic Odd GPIO behavior in LPC Microcontrollers

Odd GPIO behavior

Re: Odd GPIO behavior