TUSB422: Always looking for connection

Hi Jack,

With no connection, could you probe the CC pins connected to the TUSB422 and ensuring that you are seeing activity on those lines indicative of DRP, DFP, and UFP activity, I.E switching between pull-up and pull-down, consistent pull-ups or pull-downs?

Additionally, any schematic/block diagram you can provide would help.

Thanks,

Ryan

TUSB422 Eval Board_6Aug2024.PDF

Thank you Ryan!  Here's the schematic

If I set R1A = 0x05, I see 3.3V on CC1/CC2.

If I set R1A = 0x0A, I see 0V on CC1/CC2..

Hi Jack,

Would it be possible to capture a protocol trace of board when connecting to the eMarker, and one when connecting to a host? When connecting to the host, make sure to have the TUSB422 in UFP mode, or else there will be no connection. A trace of connecting to a host using a non-eMarker cable would be good too.

A protocol trace would help us see if the TUSB422 is communicating in the first place, and if not, whether the CC pins are the issue or not.

Thanks,

Ryan

Hi Ryan,

After reading the datasheet, my understanding was that we:

1. Check the INT register
2. Clear the INT register
3. Set the ROLE register
4. Check the CC STATUS register.
5. The BMC can only start when the CC STATUS register [3:0] is NOT 0.

We are right now stuck at #4.  When we plug in the cable, are we supposed to see CC protocols even during looking for connection?

Thanks!
Jack

Hi Jack,

We just want to see if there are any scenarios where we can get the CC pins to be detected, whether that be with the eMarker cable, or with a normal cable. If there is a connection, yes, b5 of Register 0x1D should be low, indicating a potential connection. Additionally, b4 should indicate whether the TUSB422 is presenting as UFP or DFP. If there is any communication on the CC lines, then I believe LOOKING4CONNECTION bit should be low.

If you are not seeing any changes on register 0x1D even with these different approaches, then we can see if we can try to narrow down where the issue is stemming from.

Thanks,

Ryan

Hi Ryan,

Maybe we had a cable problem.  I tried a different cable and followed the 7.3.3 to set it as DFP, and was able to see R1D[5] == 0.

Is there documentations on how to read back the eMarker vendor info?  We are trying to figure out what to do to exercise the PD PHY.

Thank you!
Jack

Hi Jack,

Jack Lin5 said:

Is there documentations on how to read back the eMarker vendor info?  We are trying to figure out what to do to exercise the PD PHY.

I'm not too sure about this, I haven't seen or heard about anything like this. I will ask around the team and try to get an answer back to you on this early next week.

For the other cable you tried, was that also an eMarker cable, or a different active cable? Or was it just a normal passive cable?

Thanks,

Ryan

Hi Ryan,

The other cable was also an emarker cable.

Thanks,
Jack

Hi Jack,

Okay, got it. Yeah, it sounds like it could be a cable issue then.

Again, I'll let you know if I hear any more info on reading vendor info early next week.

Thanks,

Ryan

Thank you!

We want to issue a discover identity command and how to receive reply via the USB PD BMC.  Any notes how how to achieve this would be great!  thanks.

Hi Jack,

Jack Lin5 said:

Using the same cable, we used the Power-Z Cable tester from Amazon (with one end of the cable open), and we were able to read back the eMarker.  So we know the cable should be good.

How is this Power-Z Cable tester communicating with the eMarker cable? Were they communicating and figuring out this information via the CC pins? Would it be possible to figure out how it is done with that for our reference?

Thanks,

Ryan

Hi Ryan,

This is the link for the Power-Z:
https://www.amazon.com/ChargerLAB-KM003C-Portable-Charging-Voltmeter/dp/B0BJ24PVNJ

We are not sure how they are reading the eMarker, but I have to assume it's via the CC lines.

Thanks,
Jack

Hi Ryan,

We found this example on Discover Identity command.  Some questions:
1. After we got Look4Connection == 0, we see R2F == 0.  Is this correct?  Do we need to set R2F to any values?
2. I can see Message Header[15:8] is mapped to R2E. Do you know where Message Header[7:0] is mapped to in TUSB422?
3. Do you know were VDM Header[31:0] is mapped to?
4. Are there steps we need to do to issue this command?

Thanks,
Jack

Hi Jack,

Jack Lin5 said:

We found this example on Discover Identity command.  Some questions:

I'm not too familiar with this command, or the means by which the CC lines communicated with an eMarker cable, so let me look into it, and I will see if I can find some answers to your questions.

Thanks,

Ryan