Misc FAQs

How do I determine the MAC address(es) of my MitySOM-335x?

Note that the AM335x features a dual MAC interface so it includes 2 MAC addresses for each processor. See this E2E post for some further details from TI (

The MAC addresses are burned in by TI and Critical Link does not record them for each module in any type of database or list. If you require the MAC address for each processor/module you would need to pull them from either UBoot or Linux and record them manually.

Assuming you only utilize a single Ethernet/MAC interface only one of those addresses will be used. If you want to record both possible MAC addresses you can do so from UBoot which I have included steps for. A little more decoding is required for the UBoot method as you will see below.

Linux read method:

  1. From the Linux prompt, login (if necessary), and type "ifconfig".
  2. In the "eth0" or similar entry you will see the "HWaddr" returned which will show the MAC address used. An example output is below showing a MAC of 00:17:EA:A9:FA:DF for this module:
    mitysom-335x login: root
    root@mitysom-335x ~ $ ifconfig
    eth0      Link encap:Ethernet  HWaddr 00:17:EA:A9:FA:DF
              UP BROADCAST ALLMULTI MULTICAST  MTU:1500  Metric:1
              RX packets:0 errors:0 dropped:0 overruns:0 frame:0
              TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000
              RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

UBoot read method:

  1. During the boot cycle "break in" to UBoot during the specified window by pressing any key
  2. Once in UBoot ("U-Boot# prompt") enter the following command: mb.l 44e10630 4
  3. Both MAC addresses will then be read from the processors registers. In the example below the MAC addresses are 00:17:ea:a9:fa:e0 and 00:17:ea:a9:fa:df
    U-Boot# md.l 44e10630 4
    44e10630: 0000dffa a9ea1700 0000e0fa a9ea1700    ................

Why am I not getting any response from the serial port?

  1. Make sure that you are using a Null Modem cable.
  2. Make sure that you are using the correct serial port settings:
    1. Baud Rate = 115200
    2. Data = 8 bit
    3. Parity = none
    4. Stop = 1 bit
    5. Flow Control = none

Incorrect cables

Please note that there have been a few reported incidents where the cable supplied with a development kit was NOT a NULL modem cable. If you believe this is your issue please contact us on the forum or at for a replacement cable.

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