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Original question:

LAUNCHXL-F28069M: Running from Flash on F28069M

LAUNCHXL-F28069M: Boot Modes v/s TRST pin state

venkatesh chilapur
Mastermind 6460 points
Part Number: LAUNCHXL-F28069M

Hi,

Can anyone help me explain this behavior on the F28069M launchpad Ver 1.1.

I have code running from flash and it blinks a LED.

I disconnect the USB, And connect an external power supply to board (from another launchpad) to the 3V3 pin on J9 header and GND.

With this connection, the device is able to boot from flash in standalone mode. Note: JP2 and JP1 are also closed. And all switch in S1 are towards ON.

I measure the voltage at TRST around S1 and find it to be low. 

so based on the Table 2-8. Stand-Alone Boot Modes with (TRST = 0), GetMode - Flash is working.

Now, I remove the external power, Just connect the USB(power on reset), the boot from flash again works and LED blinks.

I measure the voltage at TRST around S1 and find it to be High. 

So from table: Table 2-7. Emulation Boot modes (TRST = 1) it should go to wait state. Because the EMU key are not programmed.

Why is the board booting from flash even now?

  • 0
    Guru 30330 points
    Venkatesh,

    Have you observed the memory Location 0xD00 in a CCS window?

    I have a new LaunchPad which I know I have not modified and I see that EMU_KEY is 0x55AA and EMU_BMODE is 0x3, which will boot to Flash.

    I am researching a bit more into this.

    -Mark
  • 0 in reply to Mark Labbato
    Mastermind 6460 points
    Hi Mark,

    Thank you for looking in to this. When I remove the 3V3 power, the board is having no other power source and is complete power down. Now I power up the board using USB. So, it is a complete power on reset for the board. So, the RAM must not hold the EMU_KEY. Why is that the board boots in a way which makes it appear like EMU_KEY is on a non-volatile memory than volatile.
  • 0 in reply to venkatesh chilapur
    TI__Guru 55700 points
    Venkatesh,

    As Mark suggested, in emulation boot, you need to check the contents of 0xD00 and 0xD01.

    Even in Emulation boot mode, it can still boot to flash. Please check Tale 2-7. Emulation Boot modes TRST = 1) in Pg210 of www.ti.com/.../spruh18g.pdf

    If 0xD00 = 0x55AA and 0xD01 = 0x000B, then it boot to flash

    If 0xD00 = 0x55AA and 0xD01 = 0x0003 (Get mode) and 0x3D7BFB (OTP_KEY) != 0x005A, then it boots to flash

    if 0xD00 = 0x55AA and 0xD01 = 0x0003 (Get mode) and 0x3D7BFB (OTP_KEY) = 0x005A,
    OTP_BMODE = 0x3D7BFE = 0x000B, then it boots to flash

    if 0xD00 = 0x55AA and 0xD01 = 0x0003 (Get mode) and 0x3D7BFB (OTP_KEY) = 0x005A,
    OTP_BMODE = 0x3D7BFE = (0x2,0x3,0x8,0x9,0xA,0xC,0xD,0xE,0xF), then it boots to flash

    Regards,
    Manoj
  • 0 in reply to Manoj Santha Mohan
    Mastermind 6460 points

    Hi,

    The only thing surprised me is out of power on reset by connecting USB, and not launching CCS, which would programmed EMU key, the board still boots from flash. So my question was, how EMU key is persistent through power cycle. I hope I am clear.

  • 0 in reply to venkatesh chilapur
    TI__Guru** 113015 points

    Venkatesh,

    When you power the device by USB, there will be delay between power-on and TRSTn pin going to high. Look like device is power up Ist and then TRSTn goes high hence it boots up as per the BOOTPIN setting. Once emulator is connected and then you reset the device then it'll definitely BOOT as per the emulation boot.

    Hope that is clear.

    Regards,

    Vivek Singh