Did you use 2 (or more) I/O expanders? (MCP23017)

Firmware
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I asked this question in the discussion about the “Adafruit_MCP23017” library (link) but got no reaction… :wink:

As I want to monitor the messages published by 20 Photons with one Photon, turning on status LEDs, I need about 60 GPIO pins.

If I could use four MCP23017 ICs, that would be perfect. On the I2C bus it should be possible to use eight of these.

I tried my monitoring sketch out with one, using the Adafruit_MCP23017 library but cannot figure out how to control more than one chip.

Publish-Subscribe with Adafruit_MCP23017.JPG800×641 119 KB

Can anybody get me on the way?
Or is it just not possible with this library?

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If you had a look at the Adafruit_MCP23017.h, you would have seen this void begin(uint8_t addr); constructor that takes the address your object should refer to.
Create one object per chip and just do the stuff you’d do with a single one.

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Thanks for your reply @ScruffR !
That’s also what @jbeacon explained in the library discussion (LINK)

I will do my best, but I’m not sure if I can figure it out how exactly to do this.
Actually, I was hoping for an example… :wink:

PS: I’m only a hardware engineer who has programming in “wiring” as a hobby…

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I’ve used 2 or more mcp23008 and mcp23017 without problems.

If I remember it right you just use mcp.begin (x) , x being set by the address pins.

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Thanks @peter_a this is a fantastic community with brilliant brains!
I am one step closer to my target…

=> See the rest of the discussion HERE

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This is the reason why double-posting is frowned upon!
You are tying the energy of two or more people to answer the same question multiple times.

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