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Discussions on how to get your MSP JTAG programmer up and running.
By xhuo
#52845
My MSP430F2350 works fine when it is connected to Olimex programmer. But it can not be started when it is directly connected external power supply. The set/reset circuit seems no problem. I also disabled the watchdog. What could be the possible reasons cause this problem?

Thanks,
Xueliang
By OldCow
#52951
You said your F2350 cannot start when it is directly connected to external power supply. I do not understand. Is it a bare chip? And you connected a power supply (must be external, there is no internal power supply inside the chip) directly to the chip?

I assume that your F2350 is soldered on a board. The board has a JTAG connector and an external power connector. The nRST pin has a pull up resistor. There may be a LED on the board too. Anything else?

Now when this board is connected to a JTAG-tool, no external power is needed. the power is supplied by the tool via pin 2 of the JTAG connector. And the firmware works.

Now you disconnect the JTAG tool, and connect an external power supply to the board. But the F2350 cannot start.

1) What does you firmware do? Does it uses the crystal oscillator or other stuff? I suggest that you try a simple one first. Just hold the watchdog, do not change the BCS default settings, do not use the crystal, do not enable other peripherals. If your board has a LED connected to one of the port pins, enable that pin and use a simple delay loop to flash the LED.

2) Before you disconnect the JTAG-tool, did you tell it to release the JTAG and let the firmware run by itself?

3) What is the voltage when power is supplied by the JTAG-tool? What is the voltage of the external power supply? Is that power clean? Any ripples and noise?

If the two voltages above are within +-0.2V of each other, you can try the following.
(a) Power off the JTAG-tool.
(b) Disconnect the Vcc of the board from pin 2 of JTAG connector.
(c) Connect it to pin 4 instead.
(d) Connect your board to the external power supply
(e) and turn on the power of the JTAG-tool.

With this configuration, your board is powered by external supply. But F2350 is still controlled by the JTAG-tool which has its own power at the same voltage (important). Does the firmware work?