B4R Question Use PCF8574 I2C Extensions as Input pin

[tzfpg]

I used PCF8574 I2C Extensions as Input Button pin. How can I do ?

 

[tigrot]

Simply check digital input status of extension in a timer routine. It's not simple as checking a master processor port, but it's the best thing you can do. You will get a byte showing the status of each input.

 

[tigrot]

For your reference https://www.b4x.com/android/forum/t...pcf8575-16-bit-io-port-expander-module.80354/
it's a good base to start on. Thanks to rbghongade!

 

[woniol]

As I remember PCF8574 has an INT(errupt) output. It's state changes on every change on any of 8 PCF8574 pins set as inputs.
You can connect it to your board's input pin and do the readings according to that change on INT.

I used that chip some time ago...

 

[tigrot]

I don't think that B4R is able to handle interrupt without issues, but you can connect the INT pin of PCF8574 to a DIO and test it in a AddLooper sub or digital input state change event( see https://www.b4x.com/android/forum/threads/simple-interrupt-in-b4r.88209/ )