TUSB4020BI: Device detect fail

Hi Hedy,

Could you give me more information on what function this USB dongle has? Are you able to probe on DP and DM when device is inserted? Can you measure to see if dongle presents a pull up resistor to ~3.3V when connected? Is TUSB4020BI power-up sequence correct? Also please see link below for addtion debug steps that can be followed for TI USB Hubs.

https://e2e.ti.com/support/interface/f/138/t/719918?tisearch=e2e-sitesearch&keymatch=faq%3Atrue 

Hi Malik,

The USB dongle is mouse or Kingston USB drive. I will attach waveform later.

Question: Does TUSB4020BI need pre-programming?

I followed troubleshooting guide and the answer as below:

• When connected to the host, what is the voltage at the USB_Vbus pin? 0.495V
• For oscillator-based applications, does my clock input at the XI pin start before TUSB8044 comes out of reset? Yes
• Is the SMBUSz pin held low in the system? SMBUSz floating, it is "low" while booting then "high" automatically. I tried to solder SMBUSz to ground, but hub stays in programming mode and stop operating.

I floating I2C interface, and hardware configuration as SMBUSz=floating; PWRCRL_POL="1"; GANGED="0"; FULLPWRMGMTz'="1"

Please let me know anything I can check. Thanks.

Hedy

Hi Hedy,

TUSB8044 will only need pre-programming in SMBUS mode. To avoid this SMBUSz should be pulled high. If possible could you try to pull SMBUSz high externally? What is the voltage you see when the Hub is floating? Also please ensure that the power-up sequence is following section 7.7 Power-Up Timing Requirements in the datasheet. Is TUSB4020BI seen by the USB Host (PC)? 

Hi Malik,

The power sequence and level are followed datasheet.

I get the EVM today and connect with my DUT, but my problem is still exist. I list more detail including my debug steps for reference.

• Design background: TUSB4020 is designed to connect between SOC and two USB type-A connector
• Issue description:
  • Trial 1
    • power on hub but hold its reset pin
    • Plug USB flash disk (or USB mouse), SOC pull high hub's reset pin: SOC can detect USB device
    • Unplug USB device and insert USB device (reset pin is keeping high): SOC fail detect USB device
    • (Note. external pull high SMBUSz cannot fix this issue)

• • Trial 2
    • Use TUSB4020BPHPEVM connect PC
    • Plug USB mouse, PC can detect USB device
    • Unplug USB mouse and insert, PC can success detects USB device
  • Trial 3
    • Use TUSB4020BPHPEVM's U6 connect to SOC
    • Wait EVM all LEDs light
    • Plug USB mouse, SOC fail detect USB device
  • Trial 4
    • Use commercial USB hub connect to SOC
    • Plug USB mouse, SOC can success detects USB device

It seems PC can query TUSB4020 and avoid hub enter suspend mode.

SOC cannot communicate with TUSB4020 hub well, however, SOC can talk to other commercial hub and success detect USB devices.

Question:

If TUSB4020 enters suspend mode, can it detect USB device and return active mode?

Any detect mechanism (or hardware pull-high/ pull-low on which pin) can keep SOC connect with TUSB4020?

Thanks. Hedy

Hi Hedy,

What is the SOC that you are using? Is this using a non-Windows OS with custom USB drivers? The USB Host should bring TUSB4020 out of suspend using either a Reset or Resume bus condition and TUSB4020 had been configured for remote wake and the control interrupt endpoint has been setup. There is no hardware pins that would help this scenario as TUSB4020 lets the Host know when a device has been interested and Host decides when the Hub can "wake up" all over USB 2 protocol.