Okey I want to know about these pins.
SDA, SCL , A0, A1, and A2.
What are they used for?
BS2 TOW - Holonomic Boe Bot is going to commence as not sceduled!!!
I had to look that one up - and I STILL don't know what it means.
oh wait, ,you mean the holonomic wheel, not the funky mathematics.. um..
No they aren`t for controlling it, just for setting its address. Remote 8-bit I/O expander for I2C-bus is written in the title of the datasheet, don`t get this if you can`t use it.
Are you sure you can`t use I2C? Theres a lot of stuff google throws up for "basic stamp 2 I2C".
SCL and SDA are your I2C control pins. They should be wired to SCL and SDA on your micro and have 10k-22k pull up resistors.
You DID read the datasheet, RIGHT?! :)
23 pages of datasheet gloriousness, and all it took was "PCF8574" straight into google.
If you don't feel like typing all those fiddly letters into google, you can just double-click on the "PCF8574" bit and select "copy", then go to google and select "paste", that might cut down on the effort involved.
i think that sda is the serial dataline and scl is the serial clock. the pins labelled A are the address input pins.
the data sheet for this chip is here http://ecee.colorado.edu/~mcclurel/Philips_I2C_IO_Expander_PCF8574_4.pdf