TCA9548A: I2C Returning NAK

Jiahe Liu

Part Number: TCA9548A

Tool/software:

Hello,

I was using the TCA9548A and tried to do some I2C writes to it. I connected A0, A1, and A2 to GND, and the TCA9548A's address should be 0x70 according to the datasheet. However, when I tried to write to it at this address, TCA9548A returns NAK. I was wondering why this could be.

This is our schematic drawing. Is there any problem with our connections or the pull-up resistances perhaps? I am only testing TCA9548A as of now and haven't connected any slave devices yet.

All the best,

Jiahe Liu

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 317280 points

The schematic looks OK.

Please show an oscilloscope trace of the failing I²C write.

0 Nir Gilgur over 1 year ago

TI__Mastermind 18145 points

Hello Jiahe,

Can you please share scope shots of the behavior you are encountering?

Thanks.

Nir

0 Jiahe Liu over 1 year ago in reply to Clemens Ladisch

Prodigy 110 points

Hi Clemens,

Thank you for your reply! And here it is (yellow wave is SCL, red wave is SDA, and they share the same horizontal and vertical axes):

In addition, here is a screenshot of the square-wave diagram captured by a logic analyzer, in case it is helpful.

All the best,

Jiahe

0 Jiahe Liu over 1 year ago in reply to Nir Gilgur

Prodigy 110 points

Hi Nir,

Thank you for your reply too! I have attached a scope shot in my reply to Clemens, and I also attached a screenshot of my logic analyzer capture as well.

All the best,

Jiahe

+1 Clemens Ladisch over 1 year ago in reply to Jiahe Liu

Guru 317280 points

The TCA9548A's address is 1110000. But you are trying to access address 0111000.

0 Jiahe Liu over 1 year ago in reply to Clemens Ladisch

Prodigy 110 points

Thanks a lot! This solved the issue. It was my mistake.

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TCA9548A: I2C Returning NAK