Author Topic: Optocoupler?  (Read 2928 times)

SpufuZ

Optocoupler?
« on: August 22, 2006, 03:40:45 PM »
Hello.
Im new to microcontrollers and DSP...

I would like to know what the optocoupler after a MIDI input in a circuit does exactly.
Is it just dividing two circuits?

//dave

Peter Snowberg

Re: Optocoupler?
« Reply #1 on: August 22, 2006, 06:38:40 PM »
The optocouplers in MIDI keep the ground in each device separated from the ground in the next one, preventing ground loops which can cause problems from hum to blowing chips.

MIDI is what's known as a current loop interface where as things like RS232 are voltage level interfaces. The difference between them is that 0 and 1 on an RS232 interface are signaled by the polarity of the voltage present, in MIDI it's whether or not current is flowing through the LED side of the optocoupler. It's a more industrial strength style of interface but the speed is limited by the speed of the optocouplers.
Eschew paradigm obfuscation

bioroids

Re: Optocoupler?
« Reply #2 on: August 23, 2006, 10:07:05 AM »
Thanks Peter, I didn't knew that!

Miguel
Eramos tan pobres!