As I said in another thread only the other day, you have to be carefull
when using integer pointers[1].
Change your pointers to "unsigned char *" from "unsigned int *"
Jim
[1] you might try printing out the hex values of start, PBDR & PBDDR,
and see if the numbers are what you think they should. You will
find they are start+0x10, start+0x50
To C the address of (start+0x04) is the same as the address of start[4]
(the fourth integer in the integer array start) which is of course at
start+16 or start+0x10. As I said above using byte pointers is sooooo much
easier.
On Fri, 1 Jul 2011, Rekcut_Nod wrote:
> I'm attempting to run the TS sample from:
>
> ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7260-linux/samples/button.c
>
> modified slightly to toggle output on the DIO1 header, rather than the
> on-board LEDs. I'm monitoring DIO1 pin 9 (DIO_4) with a volt meter
> across a resister to ground, and it reads a constant 5.6mV, even when the
> program enters into the toggle loop.
>
> Can anyone tell me what I need to do differently?
>
> Don
>
>
> int main(int argc, char **argv)
> {
> volatile unsigned int *PBDR, *PBDDR, *GPIOBDB;
> int i;
> unsigned char state;
> unsigned char *start;
> int fd = open("/dev/mem", O_RDWR|O_SYNC);
>
> 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
> GPIOBDB = (unsigned int *)(start + 0xC4); // debounce on port b
>
> *PBDDR = 0xf0; // upper nibble output, lower
> nibble input
> *GPIOBDB = 0x01; // enable debounce on bit 0
>
> 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
> }
>
>
> // blink 5 times, sleep 1 second so it's visible
> for (i = 0; i < 5; i++) {
> *PBDR = 0xf0;
> sleep(1);
> *PBDR = 0x00;
> sleep(1);
> }
> close(fd);
> return 0;
> }
>
>
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