Quote Originally Posted by Darrel Taylor View Post
The PCF8574 is a 100khz device.

At 20mhz, you'll need to add...
Code:
DEFINE I2C_SLOW 1
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Hi Darrel! Thanks you very much for your fast answer! Have tried to add the command that you have signalled me, but have not improved the situation! Have tried to put DEFINE OSC 4 but the result is not improved! is it possible that the error is in the address ( %01110001) of the device?

Thanks very much