Firefly / Arduino / POWER SHIELD (SKU:DFR0105)

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Permalink Reply by Andy Payne on June 22, 2012 at 7:52am

Hi Carlos.  I have to start by saying I've never used this shield... so I'm just going off how I think it works and from reading the wiki.  As I understand it, this shield will accept a power input from 4.5-35V (goes to the input screw terminal).  Make sure the Input Power selection jumper is set to the left side (so it uses the external power and not the arduino power source).  Then, there is an output voltage tune pot.  I imagine that turning this rotary dial will allow you to change how much output voltage is being supplied.  Ideally, you would use a multimeter on the output voltage terminals and see how much actual voltage is being supplied as you turn the voltage tuning pot.  Now, if you don't have that, it seems like they have a special mapping function which maps the output voltage to an ADC value (0-1023) which can be read by Analog Input Pin0.  So, I would imagine if you wanted 12V, then the analog reading would be 1023 (that's by guess).  You can also turn on/off the output power supply by sending a LOW/HIGH signal to digital pin 13.  

So, I believe (and again, I've never actually used this shield) that you can easily use this with Firefly.  Simply load up the Firefly firmata sketch onto your board.  Then stick this shield on top of your headers.  Open up Grasshopper and load up one of the example sketches (probably Firefly_00_Sensing.gh).  Now, the APin0 output of the Uno Read should give you a sense of how much voltage is being sent out of the output blue terminals.  Like I said, if it says 1023, then I think that would mean that you're supplying 12V.  I would still check it with a multimeter to be sure... (also, I would guess that the 12V led indicator would light up as you turn the knob).  Now, if you want to be able to turn the output supply On/Off, then simply use the Uno Write component to send a High/Low signal out to DPin13 (use a boolean toggle and set it to true or false).  Anyway, it should be pretty easy to use.  After that, you can easily supply a consistent power supply to any of your devices up to 12V and 3A.

HTH,

Andy

Permalink Reply by Carlos B.M. on June 22, 2012 at 8:47am

Ok! I'm gonna try this!

Thank you Andy

Permalink Reply by Carlos B.M. on June 22, 2012 at 10:53am

 

Ok! This is what I've tried. But nothing happens in Analog Port 0. All of them are working like the normal arduino board. I've got always a value of 155. and they only react if I connect a sensor, giving the normal values I use to have with them. The red LED light is always switched in 3.3v... even when  I turn the potentiometer (It has 25 turns maximum, as I read in the data sheet.) But the technical service of the board didn't give me any interesting clue, when I called them... ¿What do you think it could be missing?

 

Permalink Reply by Andy Payne on June 22, 2012 at 12:37pm

155 might be an appropriate analog value for 3.3V (if it's scaled between 1.25V and 12V which I think is what the wiki page said the range was).  Did you try measuring the voltage output with a multimeter to see if you're actually getting 3.3V output?  It seems like the tuner pot isn't changing the output values.  Also, how much voltage are you supplying?  It says that the output voltage will return only upto 12V or the maximum that you are supplying (which ever is lower of the two).  For instance, if you had only 9V going into the input, the maximum output would be 9V.  However, if you fed 24V into the input, then the maximum output voltage would be 12V.  Could you check to make sure you have at least 12V going into the input.

-Andy

Permalink Reply by Carlos B.M. on June 26, 2012 at 6:19pm

 

Thanks Andy!

At last we make it work!! As you told me, I measured the voltage and I found the way to make it work with 12v.  The technical service of Arduino in my country (Spain) told me how to solve the connections between the led and the Arduino Power shield, after making it work. The secret was to use some transistors.

 

All this is because, I won an international contest in Milan, few months ago with a luminotherapy helmet remote controlled with Touch OSC, Using Firefly for Grasshopper. Thanks to your help in this forum, I could solve lots of technical challenges.  I will go there in a couple of weeks to get involved in a industrial design course. And I will try to go on working this project, Mapping with sensors the City of Milan, with  these new Arduino Power Shield And several sensors.

 

Thank you very much again Andy, without your help this wouldn't be the same!