MCP23017 A0 A1 A2 Addressing Question

Using Arduino Networking, Protocols, and Devices
#1

I have one MCP23017 chip on my breadboard. Address is 0x20 with all 3 pins to Ground (A0 A1 A2).

I've added a second MCP23017 to my board. I once saw an addressing drawing showing all the combinations of wiring up A0 A1 A2 and I've searched and cannot find it now.

For my second MCP I'm using address 0x21 and have pin 15 (A0) wired to my power line and pins 16, 17 wired to ground.

Can some confirm that is correct and in fact is 0x21 address?

Thanks...

#2

yes, the complete address of each chip is

1 0 0 A2 A1 A0

so if all gnd, you get 100000 which is 0x20.
if you set A0 high, you get 100001 which is 0x21

#3

Thank you...

#4