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Hi,
My customer uses XDS110 to programming F28377D with uniflash (ver 4.1.1078).
There is a failure message as below picture.
If TRST pin pull-high to 3.3V, the programming will be successful .
Why TRST pin should pull-high to 3.3V for XDS110 programming?
best regards,
Simen
Hi Peter,
Yes, there is a 2.2K pull down resistor at TRSTn pin.
Some F28377D devices are programmed successfully and some doesn't, the voltage of NG devices TRSTn pin is around 0.1V. My customer try to connect TRSTn pin to 3.3V and then the NG devices are programmed with no problem.
Would you please advise on this, what is happening?
Regards,
Luke
Luke,
The pull-down on the board insures that when the emulator cable is not plugged into the board, the mcu is not in the emulation mode (the emulation circuitry is disabled inside the chip). As soon as the emulator cable is plugged in, the circuits inside the emulator pod overcome the pull-down and drive the TRSTn pin high - this enables the emulation circuits inside the chip and puts the mcu in the emulation mode.
So, when you say the board connects more reliably with the pull-up than pull-down, it makes sense because you are helping the emulator to bring the TRSTn pin high to start the emulation mode. But having the TRSTn always pulled high will not get the mcu out of emulation mode when you disconnect the JTAG cable - making it not possible for software to run without the emulator.
I suspect that your problem is a damaged emulator that has trouble overcoming the 2.2K pull-down on the TRSTn pin. Please try a different emulator, or try changing the pull-down to a weaker value to get your current (possibly damaged) emulator to work reliably with the mcu target board.
REgards,
PEter