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Problem : Periodic Reset Signal

mehmet emin Cepni
Prodigy 120 points

Hi,

I designed a card with F28335 CPU (not first time) and tried to load a program but when I turn the power on, I saw below signal on reset pin : 

What could be the reason for the periodic internal reset? I checked the power on pins, external osc signal (30Mhz) and XCLKOUT (3,7MHz)

When I tried to load a program CCS 5 indicates that errors:

C28xx: Error: (Error -1135 @ 0x3FF9CE) The emulator reported an error. Confirm emulator configuration and connections, reset the emulator, and retry the operation. (Emulation package 5.0.872.0)
C28xx: Unable to determine target status after 20 attempts
C28xx: Failed to remove the debug state from the target before disconnecting. There may still be breakpoint op-codes embedded in program memory. It is recommended that you reset the emulator before you connect and reload your program before you continue debugging
C28xx: Unable to determine target status after 20 attempts

Also I removed the F28335 chip and test it on eZDSP it works fine, I soldered a new 28335 chip but still have the same problem.

Thank you

EDIT:

I changed the boot mode and periodic reset signal turns to the stable 3.3V signal but load problem couldn't solved. When I tried to load .out file I get these errors:

C28xx: Failed Software Reset: (Error -1137 @ 0x0) Device is held in reset. Take the device out of reset, and retry the operation. (Emulation package 5.0.872.0)
C28xx: Trouble Reading PC Register: (Error -1137 @ 0x0) Device is held in reset. Take the device out of reset, and retry the operation. (Emulation package 5.0.872.0)
C28xx: Trouble Reading Register ST1: (Error -1137 @ 0x6) Device is held in reset. Take the device out of reset, and retry the operation. (Emulation package 5.0.872.0)
C28xx: GEL: Error while executing OnReset(1): target access failed at (ST1&~(0x0100)) [f28335.gel:312] at C28x_Mode() [f28335.gel:38] at OnReset(1) .
C28xx: Trouble Writing Memory Block at 0xc000 on Page 0 of Length 0xb17: (Error -1137 @ 0xC002) Device is held in reset. Take the device out of reset, and retry the operation. (Emulation package 5.0.872.0)
C28xx: GEL: File: C:\Users\Mustafa Karamuk\Documents\MATLAB\PWM_Test_ticcs\CustomMW\PWM_Test.out: Load failed.

Also I measured the voltage at XRS pin at that stage, it is nearly 1V???

  • 0
    TI__Guru 61235 points

    Mehmet,

    The resets are being caused by the watchdog timer.  With 30 MHz input clock, the default WD resets will occur at 4.37 ms.  I can see this is what your scope shows more or less.  Since you cannot connect with JTAG, the WD keeps running and times out, over and over again.

    The real question is why you cannot connect with JTAG.  You've tested the chip and it is OK.  I also assume you used the same emulator when testing the chip in the eZdsp board, so that means the emulator is OK.  So the problem lies with your board.  I know you said you've designed F28335 boards before.  Maybe the issue is with the board fabriaction.  Check continuity with the JTAG signals from the JTAG header to the F28335 pins.  Check for a pulldown on TRSTn (2.2K typical).  Check the pullups on EMU0 and EMU1 (4.7K to 10K typical).

    You can also try using SDConfig utility to check the emulation connection.  It might tell us something (or it might not).

    Regards,

    David