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I need a LED that lights up when the Brain v1 is on and enabled

edited March 2014 in Hardware

Hallo, I'm approaching the end of my Hammond MIDI controller building (here a lot of post with a lot of pictures)

I'm using a Brain V1

I would like to have a led on my controller that lights up when the Brain is connected and the host is enabled.

Is there a pin where I can "bring out" such a signal? a sort of "replica" of the built-in led soldered directly on the brain surface

I was reading the wiki about the External Header JP3 and the pin #9 (RG3/!SHDN) or #13(VDD) or #14(VCC) but I'm not sure it's safe to use it and I don't know which one to choose.




  • I would recommend wiring it in place of or in parallel to the built in LED. You could solder a wire on each end of the built in LED and run the up to your indicator LED.

    You could also tap into the external pin header like you said. You would want to use pin 1 (the white arrow) for GND and pin 13 (VDD = 3.3V). You also will want a current limiting resistor and probably a big one.

  • Hi Mark,

    thank you for your suggestions.

    I'll prefer to not touch the Brain so using the external pin header would be the ideal (for me) solution.

    Having my LED a forward voltage of 3V and a forward current of 20mA the resistor should be 15ohms 1/8W, isn't it?
  • Thank you Moon for your help.

    So if I choose to go with Pin 14, how do I limit the current draw to 10mA from my LED? Is just a matter of the resistor value? 

  • Ok, thank you!

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