MCP23016 I/O expander

[Demon]

Robert,

Hi Ralph.

you should really read the I2C Specs.

I did, that's where I got the idea to go down to 1.5K for the pull-up resistors. Page 40somethings had interesting values.

Your schematic will never work.

Wanna bet? :lol: It's working perfectly.

- I pull the MCT6 for the eeprom high.
- I can read data from memory and display it on an LCD.
- I pull the MCT6 back low.
- I pull the MCT6 for the output MCP23016 high (the first one).
- I can turn on whichever LEDs are identified on the eeprom data.

I am now in the process of activating the 2nd MCP23016 which will be used as input.

The SDA Line is Bidirectional!

I know, I said that on post #12.

I2C is a BUS, so why separating the SDA lines
if there are no more than 8 devices of the same type on the same bus?

I know. I gave notes on my circuit on post #12 to explain my reasoning. Right now I'm testing with one input and one output MCP23016, but I plan on having 8 input and 8 output later. Actually, I'm going to have even more than that. I'm going to add an MCT6 for each additionnal 'network' of 8 MCP23016 devices.

If (for what reason ever) you want to isolate the bus use THIS schematic.

Link no workie, red X.

Attached is a schematic that should work for you.

No workie either.

Robert