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Original question:

LAUNCHXL-F280049C: Flash program does not run after power on

TMS320F28334: System does not always boot into flash

fred perrone
Prodigy 30 points

Part Number: TMS320F28334

GPIO pins 84,85, 86 & 87 are connected to 3.3v through 22k pullup resistors.  The system always boots properly from the emulator, but with the emulator disconnected and cycling power, sometimes it boots and sometimes not.  These are new boards, but the situation appears to be the same on the 5 units I've tested.

  • 0
    TI__Mastermind 45606 points

    Hi Fred,

    fred perrone said:
    GPIO pins 84,85, 86 & 87 are connected to 3.3v through 22k pullup resistors.

    Are these GPIOs used for another purpose after boot-up? Are they connected to circuitry other than the 22k pull-ups?

    fred perrone said:
    but with the emulator disconnected and cycling power, sometimes it boots and sometimes not.

    This is interesting, that it sometimes works. Maybe the boot-mode pins, GPIOs 84-87, are not always in the steady high-state for Flash boot and that's why it's only sometimes working. To check this, you could probe the boot mode pins to look at their states during start-up (i.e. see if they don't always get close to 3.3V), or try reducing the pull-up resistor value to make it stronger.

    Best,

    Kevin

  • 0 in reply to Kevin Allen18
    Prodigy 30 points

    Hi Kevin,  Thanks for the reply!   The boot pins are used as outputs and are connected to TI ULN2003ADR transistor array.

    However, I have just this moment believe I have located the problem.  On this new board design, I neglected to add a pulldown resistor on /TRST..

    I just soldered one in between the pins on the JTAG, and it appears to be working. 

  • +1 in reply to fred perrone
    TI__Mastermind 45606 points

    Hi Fred,

    That explains it. Glad you were able to find the cause.

    Best,

    Kevin