Hi,
We are using TUSB1044 on our daughter card and performing testing on USB protocol. We are able to test USB 3.1 at 5Gbps. However, we see that our Ellisys USB tester box cannot detect 10Gbps data. We wanted to probe the signal and wanted to debug further to observe the issue.
We used a FPGA transmitter which is set to 5Gbps and 10Gbps data rates for testing. As indicated in one of the post, the TUSB1044 device is protocol agnostic and passes through the incoming signal through it. We generate 5Gbps and 10Gbps data rates from FPGA and probe at TUSB1044 output pins after AC coupling capacitor.
At 5Gbps, we see that the signal is of good quality and swings fully. Whereas for the same setup at 10Gbps, the signal attenuates when probed using 13GHz oscilloscope. We have performed signal integrity analysis on the board and have used very low loss material and signal traces are also <3" in length.
We wanted to check whether we can improve quality of the signal passing through TUSB1044 using VOD settings. We are using I2C for register programming. We are able to write to a register and read it back, just to check that the I2C channel is fine. When we programmed the VOD register, we did not see any change when we changed the register values and not even slightest improvement in the signal quality.
We are not sure whether the programming the registers are taking into effect or not. Our questions are provided below:
1. Is there any sequence we need to follow while writing to registers and to take effect?
2. When will the effect of programming a register be seen? Immediately writing to register or need to set some bit after writing to main registers?
3. Is there any device ID register in the device with which we can check whether we are correctly accessing the registers?
4. Is there any other registers to be programmed to improve the transmitter signal quality?
5. On receiver side also we see similar issue with which the equalizer settings does not change the quality of incoming received signal when probed and this is for 10Gbps datarate. At 5Gbps, we don't need to change any settings, with default settings, transmitter and receiver signals are good.
Thanks,
Naveen
