I2C with 20MHz Processor

[Roger Eberle]

I've got a little problem with my I2C. On my prototype i've used an 16C76 clocked with 5MHz and an 24LC64. No Problem at all. After positiv tests, i increased the Osc-Frequency to 20MHz and compiled my c-Programm new, with the actual Freq. Result: No communication with my EEPROM. The EEPROM is ok, because if I decrease the frequency to 5MHz anything works well.
Has somebody expirience with I2C on 20MHz-prozessors?
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This message was ported from CCS's old forum
Original Post ID: 12464

[PCM programmer]

:=I've got a little problem with my I2C. On my prototype i've used an 16C76 clocked with 5MHz and an 24LC64. No Problem at all. After positiv tests, i increased the Osc-Frequency to 20MHz and compiled my c-Programm new, with the actual Freq. Result: No communication with my EEPROM. The EEPROM is ok, because if I decrease the frequency to 5MHz anything works well.
:=Has somebody expirience with I2C on 20MHz-prozessors?
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1. Did you change the #use delay statement when you changed
the crystal ? Example:

#use Delay(clock=5000000)

#use Delay(clock=20000000)

2. Are you using software or hardware i2c ? I don't think
hardware i2c works properly on the 16C77. I think it
only works on PICs that have a "MSSP" (16F877), and not
a "BSSP" which the 16C77 has.

3. What version of the compiler are you using ?

4. Are you testing this on a real chip, or are you using
ICE or simulation ?
___________________________
This message was ported from CCS's old forum
Original Post ID: 12467