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weirdnerd10

1.8V Power for MSP430

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Hello All,

 

I am a beginner to MSP430G2553, however all I am trying to do is get the MSP430 to execute the blink code while on 1.8V power supply. 

 

I have tried it on the launchpad board and it seems to stop working around 2.1V power supply. I then tried the barebones method by only using a bypass capacitor, pull up resistor for reset, and LED/current limiting resistor on a breadboard, but it seems that again the circuit only works down to around 2.0V. I measured the output pin while at 1.8V and it is in 10's of mV so it is not a problem of the LED getting degraded voltage levels but the fact that its barely getting any voltage.

 

Is there something special I need to set on the chip before using this at 1.8V? 

 

Thank you for your time!

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Your MSP430 would only run at 1.8V when running at low clock speeds (for both SMCLK and MCLK), I guess 1MHz would be safe. Also, note that most red LEDs have a forward voltage drop of 1.8V, other colours even higher. Your MSP430 is guaranteed to have a high voltage output of at least Vcc-0.3V when within the defined current drain, so you know your output voltage is between 1.5 and 1.8 volts.

Your best bet is to use a low current signal LED with a red colour, and even then you might not be able to power it.

Alternatively, use a voltmeter instead of an LED and verify that the output is behaving as expected.

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I didn't pay attention to the clock speed since I was using a basic example off of Energia. I will try to go back and redo the blink code while manually setting the clock speed to be lower. I was using a green LED but also probing the output pin with a DMM to ensure the voltages. I will redo this as well without the LED and just the DMM.

 

Thank you both for your help!!

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I manually set the clock speed to 1MHz and it works great!!! Thank you so much for your help roadrunner84 and chicken!

 

Take a look in the datasheet http://www.ti.com/lit/ds/symlink/msp430g2553.pdfon page 21:

post-40280-0-16720100-1426870030_thumb.png

 

From figure 1, you'll see that you can even run the MSP430 at up to 6MHz at 1.8V. BUT take care not to program the flash below 2.2V!

post-40280-0-16720100-1426870030_thumb.png

Edited by Friedl

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