On Thursday 21 July 2005 08:55 pm, Matthew Percival wrote:
> G'Day,
>
> > When I `cat 2D.serial/memory', it does not work, so I checked `cat
> > statistics/errors/BUS_*' and noticed that BUS_send_data_errors was 1,
>
> I may have been looking at the wrong thing with that: that error is
> probably being flagged at some earlier time, and as such not related to
> the problem I am experiencing.
>
> I have been watching what happens when I cat `memory' with an
> oscilloscope, and noted some rather unusual behaviour. For some reason,
> when I cat this file the `Match ROM' command (effectively, BUS_select()
> for the purposes of owfs), is being performed twice, then nothing else.
> The OW_r_mem() function in ow_2433.c, however, lists a BUS_select() call
> followed by BUS_send_data() and BUS_readin_data(), so I am not sure why
> nothing is getting called after BUS_select(), nor why that function is
> being called twice.
>
Sounds like a problem with the select.
The routine is as follows:
static int OW_r_mem( unsigned char * data , const size_t size , const size_t
offset, const struct parsedname * pn) {
unsigned char p[] = { 0xF0, offset&0xFF, offset>>8, } ;
int ret ;
//printf("reading offset=%d size=%d bytes\n", offset, size);
BUSLOCK(pn);
ret = BUS_select(pn) || BUS_send_data( p, 3,pn ) ||
BUS_readin_data( data,size,pn );
BUSUNLOCK(pn);
if ( ret ) return 1;
return 0 ;
}
Which means
1. the device is "selected"
2. The command sequence for reading a section of memory is issued (3 bytes).
3. The data is read into the buffer
It looks right to me.
> Because the DS2431 I am using is sharing almost identical code to the
> DS2433, I was wondering if anyone has either device and is able to
> observe similar behaviour, or have any suggestions as to what may be
> going on here. I watched closely, and there were definitely no
> additional calls to the omap_owire kernel driver, and if the
> BUS_*/OMAP_* functions were to fail they should produce an error, so it
> seems more likely that the functions are never being called.
>
> -- Matthew
>
>
>
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