A Couple Quick Questions About The MCP23008 And The Propeller

It has been several years since I have worked with the MCP23008 and the Propeller, and looking back at past circuitry, it is really difficult to get a quick grasp on what I did in the past, due to some real crowded circuitry. Furthermore, I believe I tested this circuitry in the past, but I am not absolutely 100% certain.

From various drawings and schematics, it looks like I powered the MCP23008 with 3.3V and used 10K pullups on the SCL, SDA, and RESET pins going into the chip.

Additionally, for pushbuttons, it appears as though I used single 10K ohm pulldowns and for LEDs I used 100 ohm current limiters.

I believe this setup worked, because I had to have some means of testing my sd interface in the past, but as mentioned I am not certain.

Do this sound right and workable?

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  • cheezuscheezus Posts: 244
    edited 2019-01-06 - 14:08:33
    Been a while since I've used the MCP23008 myself but they were pretty simple IIRC. I believe I tied reset to 3v3 directly as I simply connected the SCL and SDA to the eeprom pins (which are already pulled up).

    The MCP has built-in pullups so I'd just tie pin to one contact and ground to the other. Might want to check the current limiting resistors too.
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