On Sat, 2 Jul 2011, Jim Jackson wrote:
>
> 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
^^^^^^
surprized no one picked me up. I meant the 5th integer.
> 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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