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Battery problem + LM317 + msp430g2553

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What voltage does your led use? Maybe 1.8 v isn't enough to turn it on.


Yes, it is 1.8 V. It's checked.


The problem is that nothing happens. Whereas, doing the same to the launchpad it works ok.


Now, i am connecting a dc transformer from main power to the lm317 but i have a 50 hz wave in each led. Just in that pins of the msp430...


It's really strange...


I think that i am forgetting something that the launchpad has.

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According to the data sheet, the output ports have a voltage drop of 0.3 volts. So they can deliver only 1.5 volts in your case, which might be too low. Can you check with a multimeter that the ports are active at all? Have you checked that the output of the LM317 really is 1.8 volts? And what do you mean with "50 hz wave in each LED"?

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Is there a 47k pullup on the reset pin of the MSP430?


I just saw his schematic posted on the e2e.ti.com forum. He doesn't have a pull up on his configuration .. jeez I thought he had a working system. He doesn't. You need a pull-up and probably a small cap.


I guess the first question should be post a schematic or a picture.


When you fix this and add the pull up, power the board first with the launchpad 3.3 v and its regulator to make sure that works. If that does work then try your lm317 setup.



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