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DM8148 USB

Dennis McLeod
Intellectual 925 points

The DM8148 EVM comes with an SD card reader/adaptor in the box. It plugs into a USB port and accepts several different types of SD cards, MMC, and MS. If I put an SD card into that adaptor, then plug it into the eval board I can see the device in lsusb and the volume gets mounted. But, if instead I plug in a standard thumb drive.. like a Sandisk Cruzer or anything like that it does NOT show up in lsusb and does not get mounted. I thought it might be because of the Filesystem type being FAT or something, so I formatted a thumb drive to be ext3. This still doesn't make a difference..    I see nothing in dmesg indicating a problem.  What could be going on here? 

  • 0
    Mastermind 8715 points

    1. Are you able to see the light blinking on your USB device when you insert the same to your board. (check the same by putting it to PC)
    2. If light is not blinking, Check your .config file of the Linux kernel to check if USB is enabled in kernel. 
    3. Select/set the proper usb mode and rebuild the kernel.
  • 0 in reply to Ravikiran HV
    Intellectual 925 points

    Here's what happens for various types: 

    The Adaptor that came with DMEVM:
    - 8GB SD card inserted
    - formatted to FAT32 (id b)
    - it works fine

    64MB Thumb drive:
    - formatted to FAT16 (id 6)
    - works fine

    8GB Thumb drive:
    - formatted to FAT32 (id b)
    - no light comes on
    - not mounted
    - not seen in lsusb


    It's not just the thumb drive either, I have tried many more.. same result.

  • 0 in reply to Dennis McLeod
    Mastermind 8715 points

    Hi Dennis McLeod,

    Can you post the output of below commands.

    1. cat /proc/devices
    2. ls -l /dev/sdxx
    3. cat /proc/partitions
    4. Try to mount the device(if found) explicitly using mount command.
    5. dd if=/dev/zero of=/dev/xxx bs=1024 count=10000

    Regards

    Ravikiran

  • 0 in reply to Ravikiran HV
    Intellectual 925 points

    1. cat /proc/devices lists both "usb" and "usb_device" in "character devices" among many others. 

    2.  ls -l /dev/sd*   produces nothing

    3. cat /proc/partitions  lists only mtdblockN listings. 

    4.  ... 

    5. if it DID see my device, why would i  want to blow away everything on the stick.. including the partition table and MBR!?!?

  • 0 in reply to Dennis McLeod
    Mastermind 8715 points

    Hi Dennis McLeod,

    your usb device should be mounted as sda or sdb or sdc etc.... So cmd ls -l /dev/sd not giving any output. That means USB not detected.
    I suggested to mount the device explicitly using mount cmd bcz, some time it may detect the USB/MMC but may not mount it properly.

    Following questions need to be answered to solve the problem.  

    1. Is USB driver is up in the kernel? If not change .config file to get USB up.
    2. If ans. to Q1. is Yes, does your USB mounted properly on the /media/ or /mnt/ wherever it is. 
    3. If not mounted manually mount it.
  • 0 in reply to Dennis McLeod
    Genius 3925 points

    if a device doesn't even show up in lsusb, don't bother looking for it in sysfs or udev tree.

    Take a mulitimeter, measure USB bus voltage on the connector, see if it's there. If not check the USB_DRVVBUS signal.

  • 0 in reply to Hongfeng Wang
    Intellectual 925 points

    Hongfeng Wang said:

    if a device doesn't even show up in lsusb, don't bother looking for it in sysfs or udev tree.

    Take a mulitimeter, measure USB bus voltage on the connector, see if it's there. If not check the USB_DRVVBUS signal.

    I do have +5V on the connector.  It's strange why one type of device would work and not another. 

  • 0 in reply to Dennis McLeod
    Intellectual 925 points

    Solved. 

    Some flash drives require more power than others. The ones that did NOT work were reporting a need for 200mA or higher. The ones that did work were 100mA. If I connect a *powered* usb hub, I can then plug in any type of flash drive and it works without problem.