Quote Originally Posted by andywpg View Post
Maybe the two halves are separated by some distance?

I understand that Phillips created I2C (Inter Integrated Circuit) just for having two chips talk to each other on the same board, so there must be a good reason for it.........
No one suggested a serial interface is never needed, but in this case (reading a voltage and counting closures of a reed switch, then turning on an LED or an opto) an 8 pin device is tons and 2 PICs with a link is overkill.

If you need to divide a voltage in half, you can use an A-D converter to sample the voltage, divide the measured result by 2 then use a D-A converter to construct a voltage based on the new number. You also need a power supply, clock source, and a handful of other parts. Or you can use 2 resistors of the same value - it's up to you.