TUSB216EVM: EVM external test, eye diagram did not improve

In addition, the customer has a question:
If it is possible to directly start compensation through I2C, it is also possible. Please help confirm how to modify it to trigger HS mode!

Hi Alan,

Alan Xia said:

If it is possible to directly start compensation through I2C, it is also possible. Please help confirm how to modify it to trigger HS mode!

It is not possible to manually enable HS mode. HS mode can only be entered by the redriver seeing a USB2 HS signal.

Alan Xia said:

Let me explain why the customer did not use a fixture. The customer software set a strategy that would stimulate the Head unit to continuously send USB2.0 data packets as long as an external USB device was inserted for testing.

Could you send a block diagram of the customers test setup? Is it Head Device > EVM > Device? The expectation is that the EVM sees the host connect to an external device with a 50Ohm termination, such as an oscilloscope or a flash drive, and completes the USB2 handshake BEFORE any data is sent. Typically, the test fixture would also provide that 50Ohm termination.

My current thinking is that either the sequencing is wrong, I.E USB2 signals are being sent before a HS handshake or terminations are present, or that the current setup does not have the 50Ohm terminations the redriver is expecting. A block-diagram of the setup could help us better understand.

Additionally, for ENA_HS just to confirm, that LED will not turn on if the shunt is not pulled down towards ENA_HS. You can also use a multimeter to measure that middle pin to measure ENA_HS.

Thanks,

Ryan

Hi Ryan，

...

Head unit ->TUSB216 EVM->1.6M USB cable->USB box->USB Cable→USB cable to Differential Probe->Oscilloscope

Is there any problem with the customer's current connection test method?
The customer does not have an IF fixture, so their car computer is set to continuously send USB packet data as long as the USB device is plugged in.
Or do you have any suggestions for the customer's current test method, whether it is software or hardware.

Image upload failed,  upload again

The customer's operation process: connect a USB flash drive to the USB side of the oscilloscope to trigger the SOC to send out USB test signals. After the trigger, remove the USB flash drive and then plug it into the adapter board of the USB harness to differential probe; thus connecting to the oscilloscope eye diagram test;

Hi Alan,

This seems like a sequencing issue then to me. Thankfully, the EVM is being powered externally so that does help with this.

I would recommend unplugging the TUSB216EVM from the head unit after you unplug the USB flash drive, but keep it powered. That way, the head unit is still sending those test packets, just not connected to the redriver EVM. Then, I would connect the USB harness to the EVM via the setup you sent, and then finally connect the EVM back into the head unit, and see if that improves it.

I think with the sequence being first plugging in the flash drive and then having to unplug it and replug something else in, that is causing the issue. So adjusting the sequence should help this.

Thanks,

Ryan

Hi Ryan，

The customer chose to go to the laboratory for IF testing, but the test still failed and could not enter HS mode.
In order to eliminate the impact of Cockpit, the customer subsequently used the USB interface of the laptop for testing and found that during the handshake with IF, the following LED light of the EVM was on, but when sending the French USB data packet, the LED light went out, and it seemed that the signal improvement in HS mode was still unsuccessful.

Hi Ryan，

Supplementary test setup according to the customer's test using IF in a third-party laboratory:

When the above software is opened and no test packet is sent, both LEDs of EVM are on. However, when a test packet is sent, the LED of HS is off.

Do you have any more suggestions on this?

Hi Alan,

Alan Xia said:

In order to eliminate the impact of Cockpit, the customer subsequently used the USB interface of the laptop for testing and found that during the handshake with IF, the following LED light of the EVM was on, but when sending the French USB data packet, the LED light went out, and it seemed that the signal improvement in HS mode was still unsuccessful.

Can you confirm whether they are able to see the USB eye being boosted before they send these French USB data packets? Additionally, I would like more information about these French USB data packets are. Are these USB compliant test packets similar to what is sent in the HSETT tool? How are these packets being sent? Are they able to capture eye diagrams with these French USB data packets?

If possible, testing with the HSETT tool and then the French USB data packet and being able to compare the waveforms would be helpful, as I am not sure how similar these are.

Thanks,

Ryan

Hi Ryan，

I think the customer's test scenario is more like a device mode test, such as the test scenario in the following AN:

If device testing and verification is required, should we apply for TUSB216I-Q1 EVM for testing from customers?

Hi Alan,

If they are doing device mode testing, then VCC needs to be supplied externally to the EVM. I don't believe I see any VCC being supplied in the pictures you sent, so I want to confirm that that is the case.

Alan Xia said:

If device testing and verification is required, should we apply for TUSB216I-Q1 EVM for testing from customers?

When did they receive this EVM? Is this an EVM that was ordered recently, then there should be no issue with the current EVM. If this is an older one, a year+, then it may be good to order a new one.

Alan Xia said:

Supplementary test setup according to the customer's test using IF in a third-party laboratory:

When the above software is opened and no test packet is sent, both LEDs of EVM are on. However, when a test packet is sent, the LED of HS is off.

Sorry, I didn't see this yesterday. If you're doing device mode testing, then I'd highly recommend externally supplying VCC. Additionally, make sure to follow the guidelines set for following device mode testing in the datasheet.

Also, for this testing, we recommend having the flash drive replaced with a USB-IF device mode test fixture and connecting this fixture to an oscilloscope. Without the proper test fixture, it's possible the test will fail or will have difficulty running as expected.

Thanks,

Ryan