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F28377D Dual Core Boot GPIO Toggle Problem

Cem Koose
Intellectual 880 points

Hi,

I have a question about dual core booting on F28377D. I know CPU2 is booting under the control of CPU1. In cpu1 I have a lot of initilization routine, such as adc, dac, epwm, spi, i2c, interrupt etc. After the init routines in cpu1 I have IPCBootCPU2(C1C2_BROM_BOOTMODE_BOOT_FROM_FLASH) function to send to cpu2 IPCBOOTMODE command.

Some gpio's ownership are given to CPU2 in CPU1 initilization. Application works well both in cpu1 and cpu2 but at the beginning of the execution just after the reset, some cpu2 gpio's toggles randomly in a short duration. I verified that this unwanted gpio toggle occurs befored cpu1 initilization routine. I suspect that it may be about cpu2 bootrom or cpu1 cinit routine.

This gpio's may control a relay and I don't want an unnecessary relay switching at the beginning.Also, I don't think this is caused by a noise, gpio have a pull-down resistor at the pin, so it is not floating.

If you give some suggestions I will be glad,

Thanks,

DSP : F28377D

Compiler : CCS, v6.4.9

  • 0
    TI__Mastermind 19810 points

    CEM,

    the CPU2 bootROM doesn't toggle any GPIO, it doesn;t own any GPIO unless CPU1 applcation assigned the IOs and starts any boot mode on CPU2. This must be happening from CPU1.

    What is the boot mode on CPU1? did you set the boot mode pins to Boot from Flash? 

    Can you narrow down where the toggles are happening on CPU1? does it happen before it reaches main()? and which GPIOs are toggling unwantedly here?

    Best Regards

    Santosh Athuru

  • 0 in reply to Santosh Athuru
    Intellectual 880 points
    Hi,
    CPU1 boot mode is get mode which boots from flash. I put a while(1) at very beginning of main() before all initilization functions on both cores and I still see the gpio's toggeling after power on reset. I have led's with serial resistor on those gpios(GPIO31 and GPIO34).
    I think that the gpio's are output and high during reset and bootrom code, after that when program executes _cinit() it makes gpio's low.
    Thus I see a toggling action.
  • 0 in reply to Cem Koose
    TI__Mastermind 19810 points
    CEM,
    that is wierd, all the GPIO are input by default and with pull-ups disabled. When you enter main can you check the GPIO DIR and GPIO PID register contents for this GPIOs?

    GPIO31 and GPIO34 are not used by boot ROM at all. And I suppose this is a 337 or 176 pin package right? Which revision of Silicon is this and are you observing this behavior in more than one silicon?

    Best Regards
    Santosh Athuru
  • 0 in reply to Santosh Athuru
    Intellectual 880 points

    Hi Mr Athuru,

    The CPU is TMX version of F28377D which is a silicon revision B, BGA337 package. I will check GPIODIR/GPIOPID register and will tell the results. Also I'm desining a board that uses TMS version silicon revision C at 176 pin package, I will check this behaviour on that board.

  • 0 in reply to Santosh Athuru
    Intellectual 880 points
    I think I solved the problem. The gpios are connected to a buffer. Before the initilization, the gpios are input, so the input of the buffer becomes float. For this reason buffers have undefined states before main. If a put a pull-down resistors to gpios, it will be corrected.
  • 0 in reply to Cem Koose
    TI__Guru 57255 points

    Hi,

    You are correct.  On boot of the F28377D, all GPIO come up as inputs with the internal pull-up disabled.  As a result, all GPIO are floating - including the GPIOs that control the LEDs on the controlCARD.  In order to keep any IO at a specific state during power on, an external resistor (to pull the pin high or low) is needed.

    (note that after power up, you can write to the GPIO Pull-up Disable registers [ie GPAPUD] to enable internal pull-ups)


    Thank you,
    Brett