Jump to content
43oh

Recommended Posts

Hi all,

 

I have an msp-exp430g2, my power supply is from USB and i have another unit (LMR61428) that convert 3.3 volt to 5 volt.

 

I need this conversion unit to work only when I need. if i connect it to the VCC pin, it works all the time. Ive tried to connect it to an I/O pin that I can program to be on and off but the current output from the I/O pins is to low.

 

Is there anyway to program the VCC pins on and off? or to increase the current output of the I/O ports?

 

P.S. i tried to build an electronic switch with a bi-poler transistor but i couldnt make it work :(

 

Thanks,

 

Ofer.

Link to post
Share on other sites

If you are not confident with using a transistor (the perfect solution in this case) then you could use a relay. Some smaller relays can be driven from an I/O pin and used for switching VCC to your 5v booster on/off, bigger relays sadly need a transistor anyway such as those commonly used in automotive electrical systems.

 

Decent guide on using a transistor here though: https://learn.adafruit.com/adafruit-arduino-lesson-13-dc-motors/transistors
That is in the context of a DC motor connected to an arduino uno but could just as easily be your LMR61428 connected to the launchpad.

Link to post
Share on other sites

hi @@roadrunner84, I tried using the enable pin but i see that it only stops the conversion from 3.3 to 5 volts so the output to the load is 3.3 volts. maybe im using it wrong, do you know of a way to connect it so the enable pin would shut down the output voltage?

 

thanks,

Ofer. 

Link to post
Share on other sites

thanks @@SixSixSevenSeven i will try it, although i would have prefer a software based solution.  

Not possible to do in software, the VCC pin on the launchpad is linked to the VCC pin of the MSP430 and the onboard regulator. There is no on/off for it.

 

You're either going to have to look into the enable pin on your stepup converter or deal with the transistor.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...