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PCF8575: Driving port pin as GPIO output LOW/High

Part Number: PCF8575
Other Parts Discussed in Thread: TCA9535

Hi,

Is it possible to drive the PCF8575 pin as output LOW or HIGH.

I have schematic like below I want to control the charge enable and disable function.

> i2cset 0 0x24 0x80 0x00 // command to configure as output

How to drive this output high? The moment i execute above command I get high pulse then back to zero(may be because of 1K pulldown resistor). I want to drive this port pin as output high or low based on application. Default power up state of IO should be zero to keep my battery charger in charging mode when system load(lcd + processor + digital section) in off.

Rgds

Chandra

  • Hello Chandra,

    The PCF8575 can either be setup as either all ports as inputs or all ports as outputs, but you can't mix and match.   You can toggle between the two but you need to take precautions about how the inputs and outputs are setup.  Have you looked at other IO expanders in our portfolio that has registers that control each pin as either an input or output?  I would suggest looking at TCA9535?

    -Francis Houde