Problem to read a PCF 8574

[Darrel Taylor]

The PCF8574 is a 100khz device.

At 20mhz, you'll need to add...

DEFINE I2C_SLOW 1

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[Darklakebridge7]

The PCF8574 is a 100khz device.

At 20mhz, you'll need to add...

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

[mister_e]

I2Cread SDA,SCL,%01110001,[DATAPCF]

depending if you're using an A version the control byte may differ.

Assuming your 4.7K pull-up (or lower) are on the I2C BUS, and you also have some on the PCF i/o... it should work.

if i remind correctly, prior to be able to read read from this device, all i/o have to be at high level.

i know i forgot something...

[Darklakebridge7]

I2Cread SDA,SCL,%01110001,[DATAPCF]

depending if you're using an A version the control byte may differ.

Assuming your 4.7K pull-up (or lower) are on the I2C BUS, and you also have some on the PCF i/o... it should work.

if i remind correctly, prior to be able to read read from this device, all i/o have to be at high level.

i know i forgot something...

Dear Steve!
Thank you very much! I have resolved my problems! The problem was in the resistances from 10k that had inserted in the bus I2C, that didn't give some problem in writing but they didn't allow the reading! Have replaced her with two resistances 4K7 and the problem has been resolved!

Thank you very much!

[mister_e]

Bienvenue et bonne chance!