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set slave address as 0x49, and I can not find the device

user4832308
Prodigy 60 points
Part Number: INA226

Hi,

My PCB has 8-INA226 connected same I2C-bus. These were given own slave address; 0x40/0x41/0x42/0x44/0x45/0x46/0x47/0x49. I can find the devices from 0x40 to 0x47 by raspberrypi's i2c-tool and NXP-MCU, but I can not find 0x49. The "0x49" device is connected A0 to VS and A1 to SDA, directly. I have not looked at the waveform of SDA/SCL yet. Please give me the suggestion about my trouble.

best regards

  • 0
    TI__Mastermind 32395 points

    Hello user4832308,

    Thank you for posting to the forum. I hope we can solve your issue quickly.

    So just to confirm, the A0 and A1 connect to VS and SDA with a direct connection, so no resistors correct?

    Is there any difference in the layout of the SDA/SCL traces for the 0x49 device compared to the others? No extra bus capacitance?

    Are you able to read/write from the 0x49 device?

    Could you replace the 0x49 device with a known-good working INA226 and see if the problem continues to occur?

    A scope shot of trying to read/write from the 0x49 device will be helpful in understanding if this is a timing violation or if it’s some other error. Actually if you could grab a scope shot of the same read or write command with the 0x46 device that would be great to see side by side.

    Sincerely,

    Peter

  • 0 in reply to Peter Iliya
    Prodigy 60 points

    Hi Peter,

    Thank you for your reply.

    1) A0 and A1 connect to VS and SDA with a direct connection via 0-ohm Resister. I have checked connection and resistance value. No problem.

    2) I have made a couple of same PCB. Another PCB is same result.

    3) I try to read 0x49-device, but no device response. I can not find 0x49-device by I2C read/write tool.

    4) I have not watched scope shot SDA/SCL. I will try it just now.

     

    best regards

  • 0 in reply to user4832308
    Prodigy 60 points

    Hi Peter,

    I checked my schematic again and I found a mistake in the circuit. I fixed it and everything worked fine. There is no problem in th INA226.

    Best regards.