MCP23016 I/O expander

[Demon]

Mr Demon,

What is this Mister talk? I hope you're not doing the "vous" thing, 'cause if you are and you're just doing this to respect your elders, then I'm going to have to stroll over and hit you about the shoulders with my cane.

:P

Even if i don't see any advantage and/or need for the Optos, it also introduce, at least, a voltage drop between The PIC and the I2C device. No matter why it's working so so.

I forgot about that.

Schematic provided by Ralph will work. You just need to modify your I2CWRITE/I2CREAD statement to fit with the A0, A1, A2 jumpers.

I don't have those arts on hand at the moment.

On your SCL and SDA line, you should be able to fit all your I2C devices. As i remind MCPXXX don't have the same control word than your EEPROM so it shouldn't provide any conflict.

Steve, I want to be able to have 8 MCP23016 for input, and another 8 for output, all on a single PIC. That's why I tried the MCT6 switch idea.

For more than 8 (up to 16) devices of the same type share SCL for all of them and have separate SDA for each set of 8.

Yeah, but the PIC 16F877 only has one SDA/SCL pair of pins. Is there another PIC that has multiple SDA lines (I didn't notice this feature on the MicroChip product list)?

Robert