Jump to content
Sign in to follow this  
hamada

How to control DC motor with ULN2003 and msp430?

Recommended Posts

Hello,

I'm trying to control a 3v dc motor from msp430 launchpad connect by USB cable with array of darlington transistors circuit known as ULN2003 (data sheet in attachement)

in the picture below, I replaced the motor with red LED to protect the chip while testing. but I can't light it 

is 3v not enough to power the ULN2003?

 

post-32949-0-79319400-1460416637_thumb.jpg

ULN2003.pdf

Share this post


Link to post
Share on other sites

@hamada

your setup should work fine as far as I can tell. The datasheet from ST on page 6 says that it should be fine even with 2.4V input on the "data pin", only the output current will be lower, but it is still 200mA at 2.4V, more than enough for your led.

Maybe you could test it without the launchpad first by just applying 3.3V or 5V to the input pin on the ULN2003. If this doesn't work, I would say, your LED or the ULN2003 is damaged. Or use a multimeter to check :)

Share this post


Link to post
Share on other sites

Presuming the diagram you attache is correct, you have the LED connected to ground. As the ULN2003 switches the other lead to ground, the LE will not light. You need the anode to f the LED attached to the 3V rail, and a current limit resistor in series with it (maybe 100ohms)

 

Again, the outputs switch to ground, not positive supply.

Share this post


Link to post
Share on other sites

1) you will blow up that LED without a current limiting resistor.

2) I don't see a connection to power the ULN2003. It just might work barely through unintended back-powering through the logic pin. (Which also might have saved your LED so far.

Share this post


Link to post
Share on other sites

SOLVED: He is final working circuit, Thanks everyone for your help!

Won't work.

 

The ULN is on one side of the breadboard, not spanning the gap in the breadboard, so pins 1/16, 2/15, 3/14 and so on are bridged.

Share this post


Link to post
Share on other sites

2) I don't see a connection to power the ULN2003. It just might work barely through unintended back-powering through the logic pin. (Which also might have saved your LED so far.

The ULN2003 doesn't require power. It is darlingtons with flyback diodes

 

The ULN is on one side of the breadboard, not spanning the gap in the breadboard, so pins 1/16, 2/15, 3/14 and so on are bridged.

Whoops. I didn't notice that. If built like as shown, I concur that is another problem. I have grown used to not paying attention to the position on the board in this style of diagram, as they so often do not reflect the actual construction.

Share this post


Link to post
Share on other sites

1) you will blow up that LED without a current limiting resistor.

2) I don't see a connection to power the ULN2003. It just might work barely through unintended back-powering through the logic pin. (Which also might have saved your LED so far.

 

Well, it does have the COM pin, which is typically tied to VCC/Vsup when you drive an inductive load/motor. It's the common pin for the built in flyback diodes. But the ULN2003 doesn't have active logic that needs its own supply.

Share this post


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.

Sign in to follow this  

×
×
  • Create New...