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TCA9539-Q1: TCA9539-Q1: i2c no ack

Part Number: TCA9539-Q1
Other Parts Discussed in Thread: TCA9539,

Hi, TI engineers,

We connected tca9539 to i2c0 of tda4ve, and there is still a device max96722 on the bus that can be detected normally, but 9539 has not been detected on the bus. We have taken the following troubleshooting actions:

1. Change the 10k resistance of A0/A1 to 0ohm

2. Reduce the speed of the i2c bus to 60kHz

3. The i2c address of another 96722 on the bus is 0x6b (7bit), and it does not appear to have an address conflict issue

4. Reset, SCL, and SDA pins are all 3.2xV

5. We measured the i2c signal and found that tca9639 did not have an ack (we believe the i2c address is 0x74)

All of these are ineffective. Is there any other reason that could lead to this problem?

SDK version:

LINUX: 08_06_01_02



  • Please show an oscilloscope trace of the failing I²C access.

  • Hi Tahm,

    Current schematic shows both address pins are externally grounded making for a device address of 1110100 = 0x74. 

    As Clemens has already stated, we probably need to look at the oscilloscope waveforms to further determine the cause of the problem. In the meantime, have you tried a second TCA9539-Q1 in place of the unresponsive device? Check to see if the issue persists across multiple devices rather than a single device. 



  • Hi, Tyler and Clemens, 

    Thanks for both of your reply. we can now operate the tca9539.

    We used the open-source i2ctools in Linux to operate i2c. At first, we found that after powering on, we used i2cdetect - y - r 0 0x74 0x74, but couldn't detect tca9539. It wasn't until we executed i2cget - y - f 0 0x74 0x00 that we later found similar descriptions in the chip manual.



  • Hi Tahm,

    I am glad you found a solution. I will close the thread.