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Topic: ARDUINO BT WITH HP LEDs and LED boost puck drivers (Read 2101 times) previous topic - next topic


hi all this is my first post here. I have a bit of a problem with my arduino bt at the moment.
I have connected 2 led boost puck drivers off my arduino both gnd at the same port and one off pin 12 and the other pin 10. Each driver has 2 1w leds (350mA, 3.3V) in series with a 10k pot each driver. This is powered from a lm7805 v reg. and entirely connected in parrallel with a fan that runs at 12v DC. The supply is 12v DC at 0.4A. At first I connect the positive terminal of one the LED series to pin 13 and reset the driver, now the lights flashed with from the bootloader thingy.

I then tried to upload the blink function to the device:
I changed the sketch around so it was pin 12(unplugged on of the series just to try and get one working)
I changed the upload.verbose = true
I set the baud rate to 115200
in the void setup()
i added serial.begin(115200);

and i saved the sketch in a new location.
it worked. ( but the leds did not flash ) so i used a multimeter and the drivers are now only giving 1v to each led) when they should be giving more like before with pin 13.
I now cannot upload sketches, even with trying different timings of the reset button and uploading to i/o board. it just keeps saying the thing not in sync error. I dont know enough about the arduino bt to make the right changes or even how to reset the device properly. looking forward to a response.


Jun 06, 2009, 01:58 pm Last Edit: Jun 06, 2009, 02:01 pm by Metalfan1185 Reason: 1
I had a similar problem, actually, almost exactly the same.  I shorted a Digital Pin to GND while it was high

I believe that you may have drawn more that 40mA from one of the pins on the chip and may have damaged it.  

I replaced mine and it worked again, idk if reburning the bootloader will help. you could try it

if you get a new chip, you may look into taking the output of the digital pins, going through a 100 ohm resistor and a Diode to the gate of a MOSFET.  connect the Source to GND and the load in series with Drain to +.


This will do it:

The diode will protect the arduino from reverse currents in the case of the MOSFET shorting out.

R1 limits the gate current to a reasonable level, R2 acts as a pull down resistor that prevents the gate from staying latched on.


thanks so much guys! hopefully i dont have to replace the chip. that would be quite annoying. im giving them a shot now will report back soon.


Im not sure which MOSFET you may try, if you try any, but i could ballpark the values for ya

R1 would be about 80 to 120 Ohms,
R2 would be about 1K Ohms

and the diode can be any general purpose IN40xx series

most common MOSFETS can be like, a TIP122, or other whichever.

be careful! MOSFETS have EXTREMELY sensitive Gate pins, if you encounter that the any 3 of the pins are connected directly together with no resistance via an ohm meter, then the silicon junctions in the FET are junk and you need a new one.

good luck

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