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TMS320F280045: GPIO24 and GPIO32 not pulled up with a resistor. Probably won't boot from Flash.

Part Number: TMS320F280045

I am very new to software for this TMS320F280045PM part.  Our Hardware team just gave me an internally developed board which I need to get software to run on.  I can run & debug code from the JTAG emulator but I don't think it is running from a fresh boot without starting from the emulator.  The hardware does not have GPIO24 and GPIO32 pulled up with a resistor.  The Hardware guys have assigned these to outputs - might be grief if they are pulled high at startup.  So I'm pretty sure that without the resistors it is trying to boot from something other than Flash.  Is there anything I can do?


  • Hi Curtis,

    Thanks for your question! Like you mentioned, if the hardware has the boot pins floating, it is not really possible to ensure that they will boot in the correct mode.

    Would you be able to use other GPIOs on the device for boot-pins and add pullups to those pins? We typically suggest when just getting started to just add weak pullups to the default pins (24 and 32), since that's the easiest way to just get going.

    But you can definitely change the boot mode select pins in OTP memory though, it's just typically the second option rather than the first option we suggest when just getting started (since it requires extra steps).

    See this excerpt from the device datasheet's "Configuring Alternate Boot Mode Select Pins" section:

    Regardless though, whichever pins you end up choosing, some kind of pullup/pulldown (depending on your boot mode choice) is required on the boot mode pins to initially boot the device apart from emulation mode.

    I hope this was helpful, I apologize if this was a bit all over the place, but wanted to make sure I cover any potential questions you may have when getting started.



  • Vince,

    So the pullup resistors are still required on GPIO 24 and 32 even if I configure the boot type in OTP memory?

    I will probably get the hardware team to cut and jumper the board.  This is a Proof of Concept prototype board so not a big deal.


  • Hi Curt,

    Technically you can completely not use any boot-pins if desired (use zero boot pins). You would just need to configure the boot settings accordingly. Would that be preferable for the prototype? If the time to jumper the board will take a long time, you could try doing 0-pin boot modes instead. But if you want to leave everything without modifying the boot settings, the pull-ups on the default pins would be necessary.