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F28M35M52C: F28M35M52C

Part Number: F28M35M52C

i have 10 boards that contain concerto and tiva.

i used up to now the XF28M35h52 and the LX4F232H and all board were working.

i upgraded the boards to F28M35h52 and TMC123G .

5 boards are working fine and 5 boards faulty

on the faulty boards a periodic reset pulses exist on the common reset line

it is impossible to program both u controllers

the u controllers are using the same jtag chain

GPIO 35,34,43,47 are puled up via 10k resistors

EM0,EM1 puled up via 4.7k resistors 

please your advice


  • Tsfania,

    I'm sorry to hear that you are having some issues. I have a few questions that might help us get to the root of the issue.

    1. Are these custom boards? where both MCUs are on a single board?
    2. Were there any board changes between working and non-working state?
    3. Can you share the oscilloscope images with clear annotations?
    4. If the common reset line between the devices is toggling, can you decipher which of the devices is driving the reset line? Have you tried pulling one of the MCUs off of the board and trying them in isolation?
  • Hi dear Mark,

    thank you for reply.
    both mcu are on the same board.
    The Concerto causes the Reset pulses.
    No change have been done.

    I already found why. The Concerto try to boot from flash and no SW exist so the internal WD send Reset pulses on the x1 Pin.
    i found that if i set EMU0=0 and EMU1=1 the MCU will not try to boot.
    i did so and i am able now to program both MCUs
    from my point of view the problem is solved.
    i wonder why 5 MCUs decided to reset the system and other 5 behave friendly ( Normal SW programming via emulator/debugger) all MCUs are from the same batch.

  • Tsfania,

    I'm glad that you have resolved your issue. If the MCU did not have any SW loaded, then the reset toggling does make sense. Do you now have a 5 boards with one EMU configuration and 5 with another board config?