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TI TMS320F2808PZA Waking Up During Firmware Download

Daryl Warkentin
Prodigy 140 points

I’ve got a problem with a TMS320F2000 design where the processor is waking up during the firmware download.

We are using the SCI-A Boot mode by letting GPIO18 and GPIO29 float and grounding GPIO34 during power up. We can start the firmware download which proceeds for a short period of time and then the processor wakes up. The wake-up occurs during the boot loader download, before the FLASH is erased, so when the processor wakes up it boots into normal operation because the old firmware is still there.

Some additional info and things I’ve noticed:

-          The reset signal (XRS) is not being asserted at any time during the download

-          The wake up occurs randomly. Sometimes the firmware download completes successfully

-          The wake up only occurs on the latest revision of our PCB and the changes we’ve made are:

  • Added EMC filters (NFM21CC223R) on GPIO2, GPIO12, GPIO13, GPIO14, GPIO15, GPIO28, GPIO29, GPIO34, GPIO17
  • Changed to using a single ground plane for the processor instead of having split digital and analog grounds

 

What can cause the processor to wake-up during a firmware download?

  • 0
    Guru 192875 points
    Hi Daryl,

    EMC filters could be the culprit. As I've seen few issues arising due to to EMFs. Try replacing these chips with 0E resistors esp. on boot pins.

    Regards,
    Gautam
  • 0
    TI__Mastermind 19810 points
    few things to check:-

    is there any reason you have left GPIO18 and GPIO19 floating - are you depending on the internal pull-ups? As I understand you will be switching between between Boot to flash and Boot to SCIA whenever you want to run the application or do a FW upgrade. So if you have GPIO 18 and GPIO 19 coming up HIGH then you can either pull GPIO 34 LOW or HIGH depending on if you want to boot-to-flash or boot-to-SCIA.

    But process of deciding on which boot mode to use happens only once when boot ROM is run after reset. Once device is in SCIA boot it will not go back and read the boot mode GPIO again unless device is reset or unless the application does a branch back into bootROM. Device can get into SCIA boot mode but still boot to flash only if SCIA Boot doesn't get a proper KEY value (0x08AA) after the autobaud lock. Not sure if this is what is happening?

    can you scope GPIO34 and see if it is toggling for any reason? Do you know if a call /junp is being made back into the bootROM before erasing/programming flash?

    Best Regards
    Santosh Athuru
  • 0 in reply to Gautam Iyer
    Prodigy 140 points
    Removed all EMFs. Problem disappeared. Replaced them one by one and foudn that the EMF on GPIO29 was causing the problem. This is also the serial transmit (S_TX) pin that is used during the firmware download.

    The only effect an EMF should have on a serial transmit pin is to filter and possibly distort the serial signal. This could cause bit errors at the receiver but I'm not sure how it was causing the processor to wake up.

    Thanks for your suggestion Gautam.
  • 0 in reply to Daryl Warkentin
    Guru 192875 points
    Excellent Daryl!

    Goodluck & Regards,
    Gautam