I2C, MCP23008 and 0V on output

[aboudou]

Hi all,

I'm trying to use a MCP23008, but have an issue I don't understand :

- MCP23008 is powered on 3,3V line
- When not using it, voltage on SDA/SCL pins is at 3,3V
- When using it, voltage on SCL pin is at 2,5v and SDA pin is as 2V (same voltages if I power MCP23008 on the 5V line).
- When I set a pin to output, and HIGH value, voltage of the output pin is 0V instead of 3,3V
- Voltages on other pins (VDD and reset is at 3,3V)

What do you think the problem may be ? Issue with the RasPi ? Issue the MCP23008 ?

Thanks in advance for your help.

[aboudou]

OK, I finally found the problem.

It was just an addresses issue with Adafruit_MCP230xx code : given register adresses are wrong for MCP23008. After the fix, all is working correctly.