Midi in and out not working ;(

Hello I can’t get Midi in and out to work.

6N137 (the right chip) is in the right place. 8 is connected to vcc, 5 is gnd. I checked the connections with the diode, resistors and mcu. I even took out the optocoupler and put it in an arduinoboy, where it worked.
What else can I say. Pressing s6+s4 makes the leds go from left to right but nothing is sent through midi (though when I’m powering my shruthi from a 9v battery I noticed that during that process the screen losses contrast)

Ofcourse I didn’t see a note displayed in any corner :wink:

I don’t have an osciloscope yet.

I didn’t flash the MCU with the bootloader.

PS: When is the L8 lit?

  • L8 is lit when you press S6 (load/save page)
  • The fact that both MIDI in and MIDI out are not working is suspicious and makes the “chip damaged by an electrostatic discharge” theory more likely

When you have access to a scope, probe pin 6 of the opto… Even with a voltmeter, you should see it near 5v and temporarily moving to a lower value when a dense flux of MIDI events arrives…

woah, thank you for the quick reply :wink:

I get 5.13v from pin 6 and the value doesn’t change when I send some midi notes with a clock at a high bpm.

Maybe I’ll look for some shorts even though I didn’t find any and maybe i’ll flash my MCU with a diffrent program to check if the ports are intact.

Also maybe shruthi just doesn’t like my cheap midi->usb converter (though it works with arduinoboy).

just wanted to say that it works now :wink:

The problem was my cheap usb->midi conveter from china that I bought from dealextreme.com The pins inside it were swapped (no kidding).