TUSB1142: Data not passing through

I am suspecting the series caps missing on the SSRX lines, I don't think I can cleanly jam these in but I have ordered a new board that does have these.

Hi,

Can you share what the data looks like on the scope?

Have you tried using the TUSB1142 EVM, it may have the functionality you are looking for.

Hello Vishesh,

I'm not able to share a waveform at the moment however what I do see is a constant 1V on the RX pairs which should be the TX pairs on the flashdrive. I see the same thing when I probe the cable I'm using. Despite this being constant I believe it still is a data signal transmitting nothing since I do see the exact same thing happening on another board I'm testing with that does have data pass through.

I did think about getting the eval board for testing however I'm not sure how useful it may be since the project I'm working on is going to be a project for my company and I need to understand and learn where I'm going wrong.

What is the pinout of the connector used? Is this a type-C connector?

Yes, it is a USB-C receptacle, this is not the J1 connector however. The USB-C connector is connected to the mounting holes shown in the schematic.

Abraham Garcia said:

I'm not able to share a waveform at the moment however what I do see is a constant 1V on the RX pairs which should be the TX pairs on the flashdrive. I see the same thing when I probe the cable I'm using. Despite this being constant I believe it still is a data signal transmitting nothing since I do see the exact same thing happening on another board I'm testing with that does have data pass through.

I did think about getting the eval board for testing however I'm not sure how useful it may be since the project I'm working on is going to be a project for my company and I need to understand and learn where I'm going wrong.

Do we know where this 1V DC offset is coming from? We should see LFPS waveforms on the TX pins if you are able to probe this pin.

When can I see some scope captures?

Hello Vishesh,

I don't know where the 1V offset comes from.

Here is a waveform I managed to capture on TX2+ of the USB-C receptacle, this should be H3 on the schematic I shared. 

I have adjusted my configuration since yesterday, the configurations I set are as follows:

AEQENZ = 1

Mode = 0

A0 = 1

A1 = F

EN = 1

CEQ0 = F

CEQ1 = F

SLP_S0# = F

AEQCFG = F

EQCFG = F

VIO_SEL = F

The reason I changed this was to match what was on the Eval boards settings, this still did not work. To keep things from getting hairy, I'm not going to adjust the configurations anymore unless needed.

Hi,

Can you share a system block diagram of the test? 

What's the sampling rate of the scope/ is the probe used rated for high speed signals? 

Hello,

Please see the attached block diagram and let me know if anything's uncertain. The GPIO pin has a 10K pull-up to +3V3. All data connections on the Main PCB come from the USB-C receptacle which then go out through wires onto the PCB with the TUSB1142 on it. TX+/- and RX+/- Pairs at the bottom of the TUSB1142 PCB is the J1 connector. 

The sampling rate should be 5.00 GS/s with 100k record points.

Try replacing the TUSB1142 on the board?

The only time I have seen a DC offset on the USB bus is after ESD damage.

The board(s) haven't been shocked and I'm in an ESD protected environment, however if that offset is from ESD damage I'll still get it replaced.

Is there anything that could be preventing the TUSB1142 from working?

From what I see in the schematic snippet provided, I dont see anything that would cause this.

Are you able to send the full PDF file, so I can double confirm?

USB Panel CC Adapter Board.pdf

Hello Vishesh,

Attached is the full PDF file of the schematic. I forgot to mention that the caps I used are only 100nF as opposed to 200nF though I don't believe this might cause any issues.

Also I replaced the entire board I was using along with the TUSB1142 for a fresh one and I'm still not getting data to pass through.

I've been probing around some more and when I have the flash drive plugged in and nothing on the J1 connector, I see the following waveform on the RX+ pin. If I'm not mistaken, this should be the either the flash drive or thee TUSB1142 attempting enumeration. TX pins also don't have any activity.

This looks somewhat like an FLPS pattern, but I am not sure. Can you test on the EVM to confirm if this is a system issue or board issue?

There are too many unknowns, which makes this difficult to narrow down. Id like to see the waveforms with a known working board.

Hello Vishesh,

I'll try to get an eval board in when possible, it'll take some time for it to get here however. I'll also be designing another board that has the USB-C receptacle on the same board as the TUSB1142 just in case it might be the wires jumping my 2 current boards.

Before I place the order, can you clarify the distance measuring in the datasheet? Forexample, "minimum distance of the AC capacitors from TUSB1142" is this measurement from the center of the pads of the TUSB1142 to the center of the pads of the capacitors, or is it from the center of both components?

Hi,

This measurement is from the center of the pads of the TUSB1142 to the center of the pads of the capacitors.