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Problems with DS1307
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Ttelmah
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PostPosted: Tue Feb 24, 2009 11:59 am     Reply with quote
You never actually answered the question from PCM, early on, as to whether you have pull up resistors on both I2C lines.

Best Wishes
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Tue Feb 24, 2009 12:25 pm     Reply with quote
Do you have pull-up resistors or do you have series resistors ?

This is a series resistor. Don't do this:
Code:

PIC pin ------/\/\/\/-------- DS1307 pin


This is a pull-up resistor. You need 2 resistors. One on SCL and one
on SDA. Use a value from 2.2K to 4.7K:
Code:

    +5v ---/\/\/\/---
                    |
                    |
PIC pin ------------o---------- DS1307 pin
simons



Joined: 15 Jan 2009
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PostPosted: Tue Feb 24, 2009 12:29 pm     Reply with quote
yes 4K7 pullups on both lines...
PCM programmer



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PostPosted: Tue Feb 24, 2009 12:42 pm     Reply with quote
If possible, post a schematic and a photo of the board which shows the
connections.
simons



Joined: 15 Jan 2009
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PostPosted: Tue Feb 24, 2009 12:45 pm     Reply with quote
I'm using a test board which I bought some years ago.. i think i might don't have the schematic...
I'll try another method.. I'll build a brand new board without all the test equipment...

stay tuned.. this might work..
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