I2C and MCP23016

[keymuu]

A quick test here on a 4550 at 48mhz, shows ~250khz clk.

For the configs, I didn't know you were using the USB bootloader. The configs will be whatever the bootloader was programmed with. You'd probably need to read back the chip to find out what configs are set.

I was hoping for more of the program, there's a lot of stuff missing, and you never know, 1 statement could change everything.

Since you are getting all 0's. Maybe you should just try to read the RB0 pin without I2C, as a test. There's a pull-up on it, if you only read a 0, then something's still not right.
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I'm note anymore sure about anything...

When I use the following code to show things:

LCDOUT cmd,home3, dec battery/10, ".",dec battery//10,"V ",dec w/100," ", dec onoffpressed, _
cmd,home4, hex2 portb.0, " ", hex2 IOEbyte," ",cmd,home1

I can see on row 4 = 01 00, RB0=1 !! IOEbyte should show the button press on P1.0 but NO it does not come through
Took PIC of the PCB and read it with meProg and attached it here.

By the way, the ~250kHz that you got, are you absolutely sure that you communicated with the MPC23016 device? I'm just wondering because I have an impression from the datasheet of MCP23016 that it couldn't run that fast... Is my impression wrong?