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Last Post 14 Sep 2016 10:35 AM by  Michael Lavoie
USB power control
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Michael Lavoie
New Member
New Member
Posts:9


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09 Sep 2016 02:17 PM

    I have an existing SOM-LV design that is showing a USB port issue when using a new (to this platform) device.  When this new device is plugged into the OTG port, the USB will cycle disconnect/connect.  The device is attempting to pull ~450mA through the port.  The VBUS (+5v) is repeatably cycling on/off.

    I don't have schematic for the SOM.  As a registered user, can I get one?  (Where can I find one?)

    It appears the SOM is using the tps65950 USB-phy for the OTG port.  Is this true?

     

    I suspect the SOM can not supply the current to keep the device happy.  So the VBUS power (pin21) is being tripped off, then is cycled back on,... and so it goes.  Is there some reason VBUS power is coming from the SOM?  Why am I not seeing a USB-pwr-ena (pin25) signal from the SOM?  (So I can use my own USB power-monitoring circuit/control.)

    bradb
    Basic Member
    Basic Member
    Posts:203


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    09 Sep 2016 03:27 PM
    Michael,

    The TPS65950 power management and USB PHY on the SOM only support 100mA of current. If you have a USB device that uses more than 100mA of current, it should work fine if a power hub is used between the platform and the USB device.

    You can download the schematics from the DM37x SOM-LV product support website. Here is the link below.

    https://support.logicpd.com/ProductDownloads/DM3730AM3703SOM-LV.aspx

    You can locate the design files based on the specific SOM model number you are using. The schematics are the same for all models. It is the BOM that documents the differences between the available SOMs.

    Thanks,
    Brad
    Michael Lavoie
    New Member
    New Member
    Posts:9


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    10 Sep 2016 12:01 PM

    Thanks for the info Brad.

     

    Can I get some guidance on the use of the USB1_PWR_nEN line.

    Is there some reason why it is not being used?  (A design consideration, A USB protocol consideration, no particular reason,..?)

    How can I bring this line to life?  (A build/compile switch, go to file-X and change widget-Y,...?)

    bradb
    Basic Member
    Basic Member
    Posts:203


    --
    13 Sep 2016 09:21 AM
    Michael,

    When using the Linux 2.4-4 BSP all seems to work as expected. In this log below I connected a USB memory stick (using less than 100mA) then a camera requiring more than 100mA. This generates the error seen below as (usb 2-1: rejected 1 configuration due to insufficient available bus power). Then I connect the USB memory stick and it works. I don't see USB1_VBUS toggling.

    DM-37x# df
    Filesystem 1K-blocks Used Available Use% Mounted on
    /dev/root 98900 80712 13218 86% /
    tmpfs 120584 52 120532 0% /dev
    /dev/mmcblk0p1 3878880 34688 3844192 1% /mnt/mmcblk0p1
    shm 120584 0 120584 0% /dev/shm
    rwfs 512 0 512 0% /mnt/rwfs
    DM-37x#
    DM-37x#
    DM-37x#
    DM-37x# [ 538.593566] usb 2-1: new high speed USB device number 3 using musb-hdrc
    [ 539.027770] usb 2-1: device v046d p0821 is not supported
    [ 539.033447] usb 2-1: New USB device found, idVendor=046d, idProduct=0821
    [ 539.040527] usb 2-1: New USB device strings: Mfr=0, Product=0, SerialNumber=1
    [ 539.048065] usb 2-1: SerialNumber: 5C0DABE0
    [ 539.053344] usb 2-1: rejected 1 configuration due to insufficient available bus power
    [ 539.061614] usb 2-1: no configuration chosen from 1 choice
    [ 915.175354] usb 2-1: USB disconnect, device number 3
    [ 947.413879] usb 2-1: new high speed USB device number 4 using musb-hdrc
    [ 947.847412] usb 2-1: device v046d p0821 is not supported
    [ 947.853057] usb 2-1: New USB device found, idVendor=046d, idProduct=0821
    [ 947.860137] usb 2-1: New USB device strings: Mfr=0, Product=0, SerialNumber=1
    [ 947.867675] usb 2-1: SerialNumber: 5C0DABE0
    [ 947.872955] usb 2-1: rejected 1 configuration due to insufficient available bus power
    [ 947.881256] usb 2-1: no configuration chosen from 1 choice

    DM-37x#
    DM-37x#
    DM-37x# [ 955.096343] usb 2-1: USB disconnect, device number 4
    [ 959.304504] usb 2-1: new high speed USB device number 5 using musb-hdrc
    [ 959.738372] usb 2-1: device v046d p0821 is not supported
    [ 959.744018] usb 2-1: New USB device found, idVendor=046d, idProduct=0821
    [ 959.751098] usb 2-1: New USB device strings: Mfr=0, Product=0, SerialNumber=1
    [ 959.758636] usb 2-1: SerialNumber: 5C0DABE0
    [ 959.763885] usb 2-1: rejected 1 configuration due to insufficient available bus power
    [ 959.772155] usb 2-1: no configuration chosen from 1 choice
    [ 3859.618438] usb 2-1: USB disconnect, device number 5
    [ 3861.835754] usb 2-1: new high speed USB device number 6 using musb-hdrc
    [ 3861.986846] usb 2-1: device v1307 p0165 is not supported
    [ 3861.992492] usb 2-1: New USB device found, idVendor=1307, idProduct=0165
    [ 3861.999542] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
    [ 3862.007080] usb 2-1: Product: USB Mass Storage Device
    [ 3862.012420] usb 2-1: Manufacturer: USBest Technology
    [ 3862.017700] usb 2-1: SerialNumber: 000000000000FC
    [ 3862.046874] scsi1 : usb-storage 2-1:1.0
    [ 3863.055847] scsi 1:0:0:0: Direct-Access USB 2.0 Flash Disk 0.00 PQ: 0 ANSI: 2
    [ 3863.087341] sd 1:0:0:0: [sda] 2023424 512-byte logical blocks: (1.03 GB/988 MiB)
    [ 3863.125030] sd 1:0:0:0: [sda] Write Protect is off
    [ 3863.130065] sd 1:0:0:0: [sda] Mode Sense: 00 00 00 00
    [ 3863.156188] sd 1:0:0:0: [sda] Asking for cache data failed
    [ 3863.161956] sd 1:0:0:0: [sda] Assuming drive cache: write through
    [ 3863.230407] sd 1:0:0:0: [sda] Asking for cache data failed
    [ 3863.236267] sd 1:0:0:0: [sda] Assuming drive cache: write through
    [ 3863.686614] sda:
    [ 3864.303192] sd 1:0:0:0: [sda] Asking for cache data failed
    [ 3864.309082] sd 1:0:0:0: [sda] Assuming drive cache: write through
    [ 3864.315551] sd 1:0:0:0: [sda] Attached SCSI removable disk


    DM-37x#

    If you like I can send you a link to upload a copy of your design so we can review the USB_OTG portion.

    Thanks,
    Brad
    Michael Lavoie
    New Member
    New Member
    Posts:9


    --
    14 Sep 2016 10:35 AM

    Thanks Brad,

     

    We have found the code for GPIO13. It seems to be init to the OFF state for our HW. 

    ID 205 is GPIO 13 aka USB1_PWR_nEN  

    In  otg.cpp , in OMAPMHSUSBOTG::Init()

    Was:    GPIOSetBit(hGpio, 205);

    Is now:    GPIOClrBit(hGpio, 205);

    We are still looking into this, but this is a start.



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