How to connect and wire multiple mcp23017 port ex panders

Thread Starter

seayaker

Joined Jan 27, 2009
54
I need to connect these expanders to a Teensy 3.6 board to give me 48 more digital pins. I was told to do it this way but how would board identify mcp 1,2, or 3?mcp 2.jpg
 
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dendad

Joined Feb 20, 2016
3,084
You need to have A0, A1 and A2 wired differently for each chip. That is the address selection.
Connect to Vss or Vdd in a binary number fashion.
 

dendad

Joined Feb 20, 2016
3,084
First one, A0, A1 and A2 to Vss. = "0"
Second one , A0 to Vdd, A1 and A2 to Vss. = "1"
Third, A0 and A2 to Vss, A1 to Vdd = "2"
Fourth, A0 and A1 to Vdd, A2 to Vss. = "3"
And so on.
Look up binary numbers.

MCP23017 Address.jpg
 
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