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TUSB2046B: TUSB2046B: USB Detection Issue

SRC
Intellectual 260 points
Part Number: TUSB2046B
Other Parts Discussed in Thread: TS3USB221, , MSP430F5659

Hi,

We are using TUSB2046 Hub and TS3USB221 MUX/DEMUX in our custom design. We have host processor connected to Common USB port of TS3USB221. We have one device connected to Port 1 of TS3USB221. Port 2 of TS3USB221  is connected to TUSB2046 at Upstream Port and few high speed devices connected to Download stream port of TUSB2046. 

We have configured the Selection input of TS3USB221 Common USB port is switched to Port 2/TUSB2046. such that the We are facing following problems:

(i) The devices connected to TUSB2046  are not getting enumeration for each power cycle. 

(ii) During few power cycle, even if the device is getting enumerated, the device is not responding.

(iii) During few power cycle, TUSB2046 Hub is not getting detected at Host Processor side. And we are getting the error as mentioned in the attached image.

(iv) If the device connected to TUSB2046 is getting detected, if we switch the  TS3USB221 to Port 1/Other Device and switch again to Port 2/TS3USB221, the device connected to TS3USB221 are not getting enumerated.

 

We have also tried in following sequence

(i) Connecting device before powering up the device

(ii) Connecting the device after completely powering up the device.

But, the result is same as the previous observations.

Have anyone faced similar issue. Can anyone please suggest some solution to fix this issue. 

  • 0
    Guru 316440 points
    These errors typically indicate an electrical problem with the cable; in your case, there is probably an electrical problem between the host and the hub.

    Please show the schematic of your circuit.
  • 0 in reply to Clemens Ladisch
    Intellectual 260 points

    Hi Clemens,

    Thanks for your reply.

    Please find the attached schematics of USB HUB circuit.

  • 0 in reply to SRC
    Intellectual 260 points

    Hi,

    As per our observation, in case of working condition (where hub gets detected) the status of SUSPND pin of TUSB2046 is High. Whereas, in case of non-working condition (where hub is not getting detected), the status of SUSPND pin of TUSB2046 USB Hub is Low.

    But, in datasheet, the states of SUSPND pin defined as follows:

    We am not sure what we are missing here. Can anyone provide fix for this issue.

  • 0 in reply to SRC
    Guru 316440 points
    Are the USB_OTG_D_P/N nets connected directly to the host chip? (Which one?)

    I see that there are 33 Ω resistors before the USB connector, but none in the USB_OTG_DS_P/N nets. Is this the correct circuit for your OTG controller? (When two USB chips are connected directly together, the connection must have a characteristic impedance that is equivalent to that of a USB cable connection, so it's likely that the host/hub connection is wrong.)

    The SUSPND pin might be high because the host could have decided to automatically suspend the hub when idle.
  • 0 in reply to Clemens Ladisch
    Intellectual 260 points

    Hi Clemens,

    Thanks for your reply.

    We are using iMX6 Processor (OTG USB Port) as host.

    We have 15K Pull-down at D+/D-  at downstream ports of TUSB2046B. And we have connected MSP430F5659 to first downstream port of USB Hub. Its was recommended to have 1.5K pull-up at D+ to VBUS. Will impact USB detection?

    In few boards, the HUB is working fine if we connect the any device to any port. But, in remaining boards, even HUB is not getting detected (even if no device is connected to any port). But we observe, if we remove the recommended 15K Pull-down at downstream port of  USB Hub, USB Hub is getting detected and even device are getting detected.

    TUSB2046B

  • 0 in reply to SRC
    TI__Guru**** 176281 points
    Sankara

    The 1.5K pullup is required on the USB device side for the connection detection. For high/full-speed device, 1.5K is on DP, and for low-speed device, 1.5K is on DM. Looking at the MSP310 USB User Guide: www.ti.com/.../slau284f.pdf.

    It states that "When a full-speed USB device is attached to a USB host, it must pull up the D+ line (DP pin) for the host to recognize its presence. The MSP430 USB module implements this with a software-controlled pin that activates a pullup resistor. The bit that controls this function is PUR_EN. If software control is not desired, the pullup can be connected directly to VUSB".

    Thanks
    David
  • 0 in reply to David (ASIC) Liu
    Intellectual 260 points

    Hi David,

    Thanks for your feedback and sorry for delay in response. 

    We have 6MHz crystal in our design. The probability for Hub & device are getting enumerated and Hub not getting detected is 50%-50%. When we  tried to probe for checking the clock, we are not getting any clock signal in both the cases.

    Please let us know if there is any suggestion for this issue. 

  • 0 in reply to SRC
    TI__Guru**** 176281 points

    Sankara

    You have two 27pF loading capacitors on the 6MHz crystal, have you tried to change these two capacitors and see if you can get the clock started?

    Thanks
    David

  • 0 in reply to SRC
    TI__Guru 60870 points
    Sankara,

    It sounds like the problem may be that the host is not seeing a device disconnect / reconnect when the switch path is changed. Also if DP is always pulled high, the hub may enter the suspend state when it is really disconnected. Can you confirm that if the application is started with a particular path on the TS3USB221 enabled and it is not switched, the application works?

    Regards,
    JMMN