LPC1769 can not write GPOI0 Pin 27 28

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by gillys on Sun Jun 12 14:23:31 MST 2011

i have LPCXpresso Board LPC1769 from Embedded Artists.
It works fine .... but...i can not change the state of GPOI0 Pin 27 / 28.
Here is an example code:

#include <cr_section_macros.h>
#include <NXP/crp.h>
__CRP const unsigned int CRP_WORD = CRP_NO_CRP ;
#include "lpc17xx.h"
#include "type.h"

int main (void)
  while (1)
      while(1) asm volatile ("nop");
In the debugger I can see that PIN 27 and 28 is not set. The pinsel-register ist not changed (by me). The value of FIOPIN is 0x67ff8fff after this program.
Why I can not set bit 27 and 28 to 3.3Volt???

(Sorry for my bad english)
Best regards gillys

If I write
LPC_GPIO0->FIOSET |= (1 << 28);
The FIOSET register is set, but the FIOPIN is not!
If I use an other bit it works ... for example
LPC_GPIO0->FIOSET |= (1 << 17);
sets the FIOSET register AND the FIOPIN register...