Thanks for the reply!
Regarding the photo, I've uploaded one of the actual circuit I'm using[1]. The only difference from the MMA spec is that I'm using two 220 ? resistors in place of a 470 ?, but it's something I read others have done without any issue[2]
To be more specific than "no luck", my project's eventual aim is to handle note-on/off and control change messages. In my initial tests I'm just looking to flash the LED on pin 13 on when a note-on is received. What I'm seeing now is that the LED hard wired to pin 13 comes on and stays on.
I've actually got a saleae logic analyzer[3], so tested the inputs by putting a 1k ? resistor between pin 5 and 4 of the MIDI input and have been able to see the signal coming off of devices using the saleae. It looks good, I can decode it, etc... When I try to look at the output from the circuit however, I'm not able to detect anything not with the saleae or just a LED.
The board I'm using is an Arduino Uno, and I am using digital pin 0 (the serial in) for MIDI in. When uploading a sketch I disconnect the MIDI so it doesn't interfere, and when actually running the sketch I'm not attempting to use the serial I/O for anything except MIDI.
Thanks again for your help, and hopefully something here makes it clear what I'm doing wrong.
1: Non functional MIDI circuit | Jeff Miccolis | Flickr
2: http://www.instructables.com/id/Send-and-Receive-MIDI-with-Arduino/step9/Receive-MIDI-Messages-with-Arduino/
3: Logic Analyzers from Saleae - #1 with Professional Engineers