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xzarius
Joined: 05 Nov 2003
Posts: 2
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| pb 16f877 and eeprom 24cxxx |
 Posted: Wed Jun 30, 2004 3:50 pm |
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Hello,
Here a strange problem. 
I use eeprom 24c016, 24c064, 24c256 without difficulty with a 16f873. The same code with a 16f877 doesn't run, for example :
- 16f873
� Write 45 value at 0000 addresses - >
� Read 0000 addresses = 45 - > ok!
- 16f877 -
� Write 45 value at 0000 addresses
� Read 0000 addresses = FF - > bad!
However, the screens of data are exactly the same one with the oscilloscope. Except during the reading with the 16f877, epprom return 0b11111111. (I use 1k for pull-up.)
Thank you for your help |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jun 30, 2004 5:26 pm |
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| Quote: | I use eeprom 24c016, 24c064, 24c256 without difficulty with a 16f873.
The same code with a 16f877 doesn't run.
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One PIC is a 28-pin package and the other is 40-pin (at least for DIPs).
So you probably have two different demo boards for this.
It's likely that there is an error in the wiring on the 2nd demo board.
Also, 1K is a bit small for i2c pullup resistors. I think the specification
says you must use at least 1.6K pullups -- not smaller than that.
If it still doesn't work after checking the wiring closely, then post
a small demo program that demonstrates the problem. If you're
using the CCS driver file unchanged, then don't post that file. |
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xzarius
Joined: 05 Nov 2003
Posts: 2
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| Posted: Fri Jul 02, 2004 4:49 pm |
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hello,
Thank you for your assistance PCM.
I solved my problem. Some bad contacts were indeed causes some, but there was of another problem.
I use 8 serial 24c256. it was impossible of dialogue with these 8 memory.
After several tests, the memory appeared defective.
Return to the salesman, news memory and finished the problem... 
Still thank you 
Xzarius |
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