Re: [ts-7000] Reading GPIO ports

[Matt Godbolt <>]

Jim Jackson wrote:
>
>
> Matt,
>
> Show us the code - or at least the code snippet.
> Have you specified the port access pointer you are using as "volatile"?
>
> Jim
>








Hi Jim,

The code really is pretty much the same as the button.c demo - and yes,
it's volatile (I checked the disassembly too and that makes sense). 
I've attached the exact code (please excuse the mess in there, it's very
much a 'hack it around til it works' prototype type thing.

Cheers,

Matt
-==-




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// filename button.c
// connect a button to DIO pin 1 and ground
// blinks green and red led on the ts-7200 when button is pressed
//
// compile arm-linux-gcc -o button button.c
//

#include<unistd.h>
#include<sys/types.h>
#include<sys/mman.h>
#include<stdio.h>
#include<fcntl.h>
#include<string.h>

int main(int argc, char **argv)
{
   volatile unsigned int *PEDR, *PEDDR, *PBDR, *PBDDR, *GPIOBDB;
   int i;
   unsigned char state;
   unsigned char *start;
   int fd = open("/dev/mem", O_RDWR);

   start = mmap(0, getpagesize(), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 
0x80840000);
   PBDR = (unsigned int *)(start + 0x04);     // port b
   PBDDR = (unsigned int *)(start + 0x14);    // port b direction register
   PEDR = (unsigned int *)(start + 0x20);     // port e data
   PEDDR = (unsigned int *)(start + 0x24);    // port e direction register
   GPIOBDB = (unsigned int *)(start + 0xC4);  // debounce on port b

   *PBDDR = 0xf0;                             // upper nibble output, lower 
nibble input
   *PEDDR = 0xff;                             // all output (just 2 bits)
   *GPIOBDB = 0x0;                            // disable debounce on bit 0

for (;;)
{   
   state = *PBDR;                             // read initial state
   while (state & 0x01) {                     // wait until button goes low
      state = *PBDR;                          // remember bit 0 is pulled up 
with 4.7k ohm
   }
  
        printf("yay\n"); 

   state = *PBDR;                             // read initial state
   while (!(state & 0x01)) {                     // wait until button goes low
      state = *PBDR;                          // remember bit 0 is pulled up wi$
   }

        printf("boo\n");
}

   // blink 5 times, sleep 1 second so it's visible
//   for (i = 0; i < 5; i++) {
//      *PEDR = 0xff;
  //    sleep(1);
    //  *PEDR = 0x00;
//      sleep(1);
//   }
   close(fd);
   return 0;
}