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Help MSP430 working with USB power but not external on Vcc pin

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I wonder if anybody can give a newbie some advice.

I just started using my MSP430G2553 today. Was working great through USB and getting to grips with the basics using energia 101E0017 (I couldnt get R18 working). Then decided to disconnect the USB cable and power at 3.6V through the 3 pin header (Vcc GND, GND) was working good until I knocked the board and a cable must have shorted something, as the board will no longer power through Vcc but will when using the USB cable. Powering through the Vcc on the 3 pin header or the 10 pin header on the left side of the board I get 3.6 volts on pin1 of the chip (+ve supply of the chip) but also on pin 20 I believe the ground pin of the chip. I cant understand why this should happen with external power but not when powered by the USB.

Programs can be uploaded to the board. I've tried various sketches they all work.

I'm just getting back in to electronics so I've probably missed something obvious.

(A side note should the Vcc jumper be removed when powering externally or does that not matter.)

Any help would be gratefully appreciated.

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@BinaryA , This is from the user docs:

"The jumper J5 VCC also must be opened if the LaunchPad development kit is powered with an external power
supply over J6 Table 1 or the eZ430 interface J4."

Take look at: slau318.pdf (I'd provide a direct link but my holiday park wifi seems a bit challened here in Australia)




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Hi Bob

Thanks for that. I'll remember that for the future.

I did this after the short, in case I had blown one of the other ICs but still cant power the 430.

I'll just have to program it on the board and test with external power off board.

Thank you for all the help.



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