Hi,
I have a project, where I want to use a single board, but I have multiple outputs required:
Sparkfun Motor Board requires 5V for the board itself and then VIN for the motors that are each 5v
Sparkfun Sound Detector requires 3.3V for the board
I wanted to power everything off a single board, i.e. the Uno plugged in with a DC adapter, but I'm afraid if I output the VIN to all of the boards I will fry them if my power source I'm inputting is 12v above the 5V operating voltage.
How do people deal with this? Can I plug one thing into 3.3V, another into 5V, and then something else into the VIN? Or does the board not work this way?
You really don't want to power the Uno directly from the 12V supply. Theoretically it is possible but the onboard regulator will struggle to dissipate the heat. Probably better to use a DC-to-DC (buck) converter to drop the voltage to something more tolerable..
What kind of current does the Sparkfun motor draw?
If You power the controller via Vin You should not power anything more the an LED or two with the board.
Read the specification for the controller. Never exceed Absolut maximum rating on Vin. A blow up comes instantly.
Logic supply voltage (VCC) can be in the range of 2.7--5.5VDC, while the motor supply (VM) is limited to a maximum voltage of 15VDC. The output current is rated up to 1.2A per channel (or up to 3.2A for a short, single pulse).
Also, does using the barrel mean I'm powering the VIN? Or does the board just know if something is plugged into the VIN pin? A little confusing.
Yes, it's the same, almost. I think there's a diod involved but it doesn't change anything.
The logic parts need 5 volt. If the motors are 5 volt motors You should apply 5-6 volt to the motor power Vin.
Vin is a common name used for controller boards, Barrel Jack and the Vin pin. Your things looks like containing a motor driver part also having a "Vin pin".
Make sure You know what it's connected to, what it's supplying.
Your link to Sparkfun goes to a sales site. Datasheet had been telling much more.
Vin and the power jack both feed the on board 5V regulator. The on board regulator is not heat sinked so will dissipate little heat before it overheats and shuts down (best case). That is why it is suggested that you drop the 12V to 5V with an external buck converter and connect that 5V to the 5V pin on your Arduino. That will bypass the weak onboard regulator.
There is 50mA available from the on board 3.3V regulator.
Be sure to connect all the grounds, ideally at one point (star grounding).
Yes, the barrel jack and VIN are the same, both are connected together to the input of the voltage regulator. So in this case you have 12V there.
And the 5V pin can only provide 500mA, I think. And it powers the Arduino and everything connected to it. So, I think that you shoudn't power the motors with that.
And anyway, to use the 12V source is possible, but the regulator will have to waste 7V in heat.
I think that the easiest would be to get a 5V transformer with barrel jack, and then you could power the motors from VIN, if there is enough current for everything
Care should be taken when also connecting USB for communication. The 5V from the 5V pin might flow back to the PC. I'm e.g. using a Mega for addressable LEDs. My approach is to have a 5V power supply for the LEDs and a boost converter to create 9V for Vin; that prevents the issue.
@mpromeo
It does not look like you need 12V so I would use the above approach; the sound detector can more than likely be fed from the 3.3V pin. You need to pay attention to the signal levels of the sound detector; feeding a 5V output signal from the Uno to a board powered with 3.3V can damage the board. Can you provide a link to the sound detector?
That is if you feed from USB; I think that the 5V regulator can actually do less.
This is all really great advice, sounds like the VIN is not the solution, but power the logic boards via the arduino and anything else should have a separate power supply.
VIN as the name implies is a Voltage INput not an output.
There is no problem supplying an UNO with 12V to VIN or the barreljack, provided you don't draw any more than 50-75mA from the I/Os or the 5V output.
Don't connect a voltage source to the 5V output unless you know what you are doing.
