I2C Devices not detected correctly

[jmartin1208]

I have wired the I2C Extender into the the circuit, however the raspberry pi is is detecting multiple devices instead of the single i2c chip that is connected.

Running the i2cdetect -y 1 command shows every address is in use.

I am sure that I am missing something fairly simple, but for the life of me I cannot figure this one out. I have validated that the i2c device (MCP23017) is receiving the appropriate power.

[Mark Mayhew]

jmartin1208,

Have you set the circuit up without the I2C Extenders? It is best to verify that the circuit works as intended without the I2C Extenders first.

Assuming that the circuit works without the extenders, can provide more detail about how you have everything connected? How many series nodes and end nodes do you have? Where are your pullup resistors? How long is your cable run? What are the power sources for each element in the system?

Thanks,
Mark

[jmartin1208]

The circuit does work without the Extenders. I ensure it was working prior to inserting, but then removed them from the circuit and verified everything was still operational.

The circuit is fairly simple as I am only using 2 End Nodes. The cable length for testing at this point is only 5ft, so relatively small, but the intention is to extend that to roughly 100 ft in the final design.

The circuit leverages a 12V supply (8 – AA batteries) for connecting the Power Extenders, but is run through a 5V Regulator (7805) for powering the chips. The SDA & SCL pins are running into an MCP23017 chip that is being is used to drive other components.

Where I may be missing is the pullup resistors, any guidance that you can provide?

[jmartin1208]

Any update? I have added the pullup resistors but still no luck in getting the signal through the line.

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