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TMS320F28335: POR vs XRS

Bryon Powers
Prodigy 90 points
Part Number: TMS320F28335

I have a TMS320F28335 that uses multiple serial channels for communications with a PC (via Modbus protocol).  The device firmware can also be re-flashed via a PC using serial communications.  If I follow this procedure when re-flashing, everything works as expected.

>>>Power down the device.  Set the boot pins for serial flash. Apply power to the device. Reflash using PC. Power down the device. Set boot pins for boot to flash. Apply power to the device. Code runs correctly.

Again, this procedure works fine. If however, I use the following procedure:

>>>Set the boot pins for serial flash. Reset device (via XRS pin). Reflash using PC. Set boot pins for boot to flash. Reset the device (via XRS pin).

The new firmware runs, but I cannot communicate with the device on any of the serial channels via Modbus.  If I power cycle the device, communications work.  It acts as though there are differences between a power on reset (POR) and an external reset (XRS).

Anyone have any ideas?

  • 0
    TI__Guru 55700 points
    Bryon,

    When you tried to program flash using XRSn method, did flash program successfully? Did you compare flash memory contents? Was it programmed correctly?

    Regards,
    Manoj
  • 0 in reply to Manoj Santha Mohan
    Prodigy 90 points

    Yes, the flash was programmed correctly.  I am still investigating, but I believe it is a hardware issue.  I had a ribbon cable that was not making good connection between two boards.  Strange that it would exhibit this symptom though.  Will post an update once I know more.