Power a Teensy via MIDI Port
- Thread starter yeahtuna
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Jp3141
Well-known member
I doubt there's enough power available -- MIDI just guarantees 5 mA (although usually provides more), and when connected to an optocoupler input (required for safety), you'll get less than that.
Basically (see http://www.personal.kent.edu/~sbirch/Music_Production/MP-II/MIDI/midi_physical_layer.htm), a MIDI IN will (may) have a 280 Ω to 5 V, but the pin will alternate between 5 V and 0 V as data is received.
Because the signals are pulsed (serial data), power might not be present for relatively long times. If you could figure a way to boot the Teensy in a low power (low speed) mode, and keep it running with a low duty cycle, you might be able to parasite enough power, but it's complex.
Basically (see http://www.personal.kent.edu/~sbirch/Music_Production/MP-II/MIDI/midi_physical_layer.htm), a MIDI IN will (may) have a 280 Ω to 5 V, but the pin will alternate between 5 V and 0 V as data is received.
Because the signals are pulsed (serial data), power might not be present for relatively long times. If you could figure a way to boot the Teensy in a low power (low speed) mode, and keep it running with a low duty cycle, you might be able to parasite enough power, but it's complex.
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