Author: Tom Zicarelli

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Arduino pull-up, pull-down resistors

notes

If you are hooking up a switch of some kind, you can eaily make use of the internal pull up resistor.  Usually we use a switch to turn on the electricity.  You push the button and the line goes high.  and you would need a pull down resistor to tie the input low.  But we also make the electricity go the other way.  You use the pull up resistor to tie the input high.  You hook one end of the switch to the input and the other end to ground, then when you push the switch the input goes low.  Then in your software you look for the input to go low when the button is pushed versus high.

from this thread: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1205614794

 

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Using Arduino MIDI shields/library

notes

To connect the Sparkfun MIDI shield, all you need connect is rx, tx, gnd, and 5v

Here is documentation for MIDI library:

http://arduinomidilib.sourceforge.net/a00001.html

Midi thru is enabled by default and can be disabled by MIDI.turnThruOff()

There were problems running MIDI library on an arduino UNO with the USB cable hooked up.  So I’m not sure what interaction is happening with the Serial comm stuff in that case, but everything works fine with external power source.

(Update) tried running the shield with minimal connection as above and had no problem using USB power connection.

MIDI out via USB

cable converter:

 http://shiftmore.blogspot.com/2010/01/quick-and-dirty-arduino-midi-over-usb.html

Midi In via USB Host shield (for MIDI devices that normally hook into a computer via USB)

http://www.circuitsathome.com/mcu/interfacing-midi-devices-with-arduino-using-usb-host-shield

http://www.circuitsathome.com/products-page/arduino-shields/usb-host-shield-2-0-for-arduino/