AM335X and TPS23861. I2C problem

Roman Shibin

Prodigy 80 points

Other Parts Discussed in Thread: TPS23861

Hi.

Now I connect AM335X and TPS23861. Please see attach part of scheme. I use I2C1 interface and opt-isolator.

But SDAO always 0 (zero). I check Vcc and Reset. Vcc is 3.3V. Reset is 3.3V

In result I2C1_SDA = 0 too. And Linux not detect chip on I2C1 interface.

Why SDAO is 0?

over 11 years ago

0 Biser Gatchev-XID over 11 years ago

TI__Guru**** 393215 points

Hi Roman,

Check whether the return path optoisolator on SDA isn't the one that's pulling SDA low.

0 peaves over 11 years ago in reply to Biser Gatchev-XID

TI__Guru 64665 points

This question seems to be related to the operation of TPS23861. This E2E forum is for AM335x. I recommend looking for an E2E forum for TPS23861 and post your question there.

I would like to encourage you confirm the current required to forward bias the LEDs in opto-isolator is less than the steady state current rating of the respective AM335x terminal.

Regards,
Paul

0 Roman Shibin over 11 years ago in reply to peaves

Prodigy 80 points

Paul. Thank you. I will send question on E2E forum from TPS23861.

P.S.: Problem was solved. I found SDAO always is 0 if VPWR not connect. This is my case, because I use external high-power block. But this logic in TPS23861 is

unusual.

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AM335X and TPS23861. I2C problem