PCF8574 to expand output

[Simone Valmacco]

Hi!
I'm working on a compact aquarium controller with Ferduino software. I've made a board with 8 solid state relay (Triac BTA12 and MOC3043M) all controlled by a PCF8574.
Can I use this expander with Ferduino to replace PCF8575 (with all the changes that are needed)?
Can you suggest me the best way to change it? With PCF8574 outputs I'll control the heater, the chiller and some other things with the timers integrated in the software.
Also can I use the same I2C bus (SDA pin 20 - SCL pin 21)for both DS1307 RTC and PCF8574?

Thank you very much
Simone

[Fernando Garcia]

Hi!

Can I use this expander with Ferduino to replace PCF8575 (with all the changes that are needed)?
Can you suggest me the best way to change it? With PCF8574 outputs I'll control the heater, the chiller and some other things with the timers integrated in the software.

Yes, use this library.

Look to this examples:

https://github.com/skywodd/pcf8574_ardu ... nBlink.ino

viewtopic.php?p=346#p346

Also can I use the same I2C bus (SDA pin 20 - SCL pin 21)for both DS1307 RTC and PCF8574?

Maybe you can find some answers using the search.

http://ferduino.com/forum/viewtopic.php ... c+i2c#p143

http://ferduino.com/forum/viewtopic.php ... c+i2c#p516

Best regards.

[Simone Valmacco]

Hi,
thank you very much for your answer!
I'm trying the library that you've suggested me; How can I change the pin where I'll connect the expander? maybe I'll connect the PCF8574 to the pin 18 - 19
Thank you very much again
Simone

[Fernando Garcia]

Hi!

This is impossible. Use pins 20 and 21.

Best regards.

[Simone Valmacco]

Hi,
So, how can I move (directly inside of the library if it is possible) the pin of the RTC?
P.S. I'm also having some problems with the example code of the PCF8574 library; I can't compile it with the arduino IDE...