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RM46L852: Serial communication inconsistencies

James Bocinsky
Prodigy 60 points
Part Number: RM46L852

I'm currently at an internship and am new to using the Hercules dev board. My task has been to prototype multicast using lwip for an application.

The code base uses logging statements through the serial output of the board. Yesterday I was able to use putty to connect to the board and receive these outputs, using COM4 and speed 115200 speed. I would like to get the serial communication back up as it is a good way of verifying different steps of the program have been initialized correctly without having to manually debug the program.

I've verified that the COM port is the same today as yesterday and I've tried restarting the board and my computer as well as using different cables to see if any of those could be the issue, but to no avail.

If anyone could give me insight on how to further debug the dev board and it's serial communication through putty I would greatly appreciate it.

  • 0
    Intellectual 610 points
    Tap the serial line to see (or hear) whether the problem is on the sender's or receiver's side.
  • 0
    Expert 1995 points
    Some simple PC side suggestions:
    wires become loose or previously contacting connections are not secure.
    serial continuity testers with LED lights are available at low-ish cost.
    serial drivers sometimes have timeouts (USB to serial might have USB timeout or inactivity behavior)
    serial drivers sometimes are connection limited and only work for a first connection (reboot PC to see if that is a possible cause).
  • 0 in reply to NeilBerry_at_Parker
    TI__Guru 68930 points

    Something that students miss quite often is the voltage levels of the serial connection.


    This won't apply if you are using the USB<>SERIAL com port that is built into a TI kit, but if you connect your own serial port

    to a hercules board, you need to make sure that the voltage levels are LVCMOS when you connect them to Hercules.

    So:

       - don't connect Hercules pins directly to a PC's DB-9 serial port

       - don't connect Hercules to a USB->Serial adapter that you may have bought for Arduino where the IO levels are 5V


    Do use a USB<>Serial adapter that supports 3.3V IO levels