There has obviously been some problem with the code since the bus-read/write
operations in OW_w_mem() has been split up into multiple operations with
lots of debug-output.
/* Re-read scratchpad and compare */
/* Note: location of data has now shifted down a byte for E/S register
*/
//ret = BUS_select(pn) || BUS_send_data( p,3,pn) || BUS_readin_data(
&p[3],1+rest+2,pn) || CRC16(p,4+rest+2) || memcmp(&p[4], data, size) ;
ret = BUS_select(pn);
ret = BUS_send_data(p, 1, pn);
ret = BUS_readin_data(&p[1], 3 + rest, pn);
ret = CRC16(p, 4 + rest); // this fails according to your tests...
ret = memcmp(&p[4], data, size);
The read/write buffers and lengths are not the same in the first expression
compared to the following rows... Perhaps it's just some typos when it was
split down into multiple lines.
I don't have any working DS1923 at home so I can't test the code. The
CRC-check should be fixed and not removed to make sure we don't break any
more DS1923 devices by sending them into a hanging state with the oscillator
turned off.
Paul, do you have any DS1923 devices at home?
/Christian
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Michael
D. Petersen
Sent: den 29 juni 2008 06:06
To: owfs-developers@lists.sourceforge.net
Subject: Re: [Owfs-developers] DS1923
Found the source of the problem, but I'm not sure why it is a problem.
ow_1923.c (OW_w_mem):
ret = CRC16(p, 4 + rest);
if (ret) {
printf("OW_w_mem: crc err1\n");
}
The CRC16 fails, causing the read of temperature and humidity to
fail. I was feeling brave, so I simply changed the CRC16 call to the
following:
ret = 0;
That worked! Both temperature and humidity appear to read back with
reasonable values.
As a little background, this write routine is called as part of
OW_oscillator to make sure the oscillator is enabled before a read
operation (presumably to prevent the latchup condition in this
part). Not sure why the CRC fails, but the write seems to
work. Hopefully someone else can help explain that.
Michael
At 07:57 PM 6/28/2008, Michael D. Petersen wrote:
>What is the latest level of support for the DS1923? The list of
>devices (http://owfs.org/index.php?page=standard-devices) says there
>is no support, but when I plugged one into the bus, it was
>recognized. However, both the temperature and humidity files are
>unreadable (yes, I did make sure the RTC was running). Just curious
>if this is truly the current state of things.
>
>Thanks,
>Michael
>
>
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