At 08:54 AM 6/06/2002 +1000, you wrote:
>John Brown wrote:
>>I am trying to hook a Dallas 1302 Timekeeping chip up to a 16f877. I am
>>using PortD 4-6 for the 3-wire interface, and the read/write routines
>>available from Dontronic's rtc1302.asm file (appropriately modified to
>>work on the pins I have selected). Is there any problems with using these
>>routines on a 877? Are there better ones?
>>
>>My main problem is that I can't seem to get it going, which is always
>>annoying! I was wondering if anyone has any ideas? I have confirmed that
>>the chip is correctly wired to the correct pins :-) and as far as I can
>>tell it is all wired up correctly.
>
>If what way does it not work? Can you read & write the time?

I attempt to write the time, wait 10 seconds and then read it back. But the
results of my attempt to read are all zeros. I have no idea if the attempt
to write to it is working, or if the time is ticking over. At this stage I
am assuming that I am not writing successfully to the chip and therefore it
isn't ticking.

My understanding is that all I have to do to start it tick is clear bit 7
of the second register (which I then write to the chip), but I assume this
message isn't getting through at the moment.

 >         bcf     second,7        ;clear `clock halt' CH bit

Actually, I just remember that one thing I am not doing correctly is that
the numbers I write to the chip should be binary coded decimal, when in
fact at the moment my code is writing just plain decimal. This shouldn't
stop the communications though, I should just be setting to the wrong time
and date! Setting the wrong time and date would be better than nothing!

Thanks,

John


>Does the time tick over by itself?  I used the DS1307 a while
>ago & you have to set the oscillator bit in one of the registers
>to get it running. I don't know if the DS1302 is the same but it
>may be worth looking at.
>Regards...
>
>___________________________________________
>David Duffy        Audio Visual Devices P/L
>U8, 9-11 Trade St, Cleveland 4163 Australia
>Ph: +61 7 38210362   Fax: +61 7 38210281
>New Web: www.audiovisualdevices.com.au
>___________________________________________

_______________________________________________________________________
John Brown
PhD (Clinical Psychology) candidate
                                       Email:  john.brown@anu.edu.au
School of Psychology                  Phone:  (02) 6125-3827
Room 124, Building 39, Psychology     Fax:    (02) 6125-0499
The Australian National University    Mobile: 0429 455 504
ACTON ACT 0200   Web: http://www.anu.edu.au/psychology/staff/BrownJ.htm

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