TCA9535: I2Cdetect can not detect TCA9535

Mike Hsu

Prodigy 20 points

Part Number: TCA9535

Hi there

We just want to detect TI TCA9535RGER. However I2Cdetect -y -r found no such device

Please check if the following is correct or not.

PS. SCL, SDA, and INT# have pull up resistors on the other page.

3 months ago

0 Tyler Townsend 3 months ago

TI__Guru 55808 points

Hi Mike,

Can you confirm that device address 0x20 is being sent with I2Cdetect?

Do you have a scope capture of what is being sent on SDA and SCL?

Regards,

Tyler

0 Mike Hsu 3 months ago in reply to Tyler Townsend

Prodigy 20 points

Hi Tyler

We did not see 0x20 is being detected. I2C is connected PCH directly.

Waveforms as below

Any suggestion?

0 Clemens Ladisch 3 months ago in reply to Mike Hsu

Guru 320330 points

Check the TCA9535's VCC pin.

The first waveform is for address 1011000.
The second waveform is for address 1110110.
The third waveform is for address 1110100.

The address of the TCA9535 is 0100000.

0 Tyler Townsend 3 months ago in reply to Mike Hsu

TI__Guru 55808 points

Hi Mike,

I second Clemens' comments here. The I2C address seems incorrect:

Regards,

Tyler

0 Mike Hsu 3 months ago in reply to Tyler Townsend

Prodigy 20 points

Is there any power on sequence for this IC? for example, VCC--> address?

0 Tyler Townsend 3 months ago in reply to Mike Hsu

TI__Guru 55808 points

Hi Mike,

I believe this device can dynamic address. Once VCC is powered up, the address is set. You may change the A2/A1/A0 pins between start and stop conditions before initiating a new I2C transaction.

https://www.ti.com/lit/an/scaa137/scaa137.pdf?ts=1762527927881&ref_url=https%253A%252F%252Fwww.google.com%252F

Regards,

Tyler

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TCA9535: I2Cdetect can not detect TCA9535