SammichSID App Upload Problem - how to troubleshoot?

[Pete Brown]

Hi All

I've completed my sammichSID build, but I can't get MIOS Studio 2.2.2 to recognize the device.

• I double-checked that I have the right resistors in the right places
  
• I've done the loopback test and it passed
  
• I did the sysex test and it passed.
  
• The MIDI light on my MOTU 828mk3 blinks as the firmware is being sent to the sammich (although the sammich never changes from "Ready.")
  
• I have the JMI and JMO jumpers in the correct positions
  
• When I power on my sammichSID, I see the upload request.
  
• When I try and scan for the device, I get the "No response from MIOS8 or MIOS32 core...".
  

The MIDI troubleshooter starts getting specific at that point, and doesn't seem to apply to the sammichSID. IOW, the resistor numbers and other things don't really mean anything to me in the context of a sammichSID build.

Ideas on what to test? With the opto coupler in there, it's not like I can check continuity ;) I suppose I could bypass that, but I'm not sure that's the first thing I want to try. That said, the soldering *looks* ok to me. There's not much there in any case, it's pretty much a straight shot to the PIC.

Next step is to try the LED test on the MIDI in. Other suggestions?

Pete

[Pete Brown]

Did the LED test by removing the isolator from the socket and sticking an LED from the input to ground. During the sysex upload, it lights up nicely.

So, I assume bad 6n138 then? Would figure if so, since I have to order those online :P

I have a bunch of 6n136 around, but they don't seem to be a drop-in replacement.

Pete

[Pete Brown]

Ok, I figured out a way to test the isolator. I took that same LED and wired it up to the common (center pin) part of the JMI pin and ground. It stayed dimly lit, but pulsed in time with the MIDI messags coming from MIOS Studio.

So now I'm thinking this is uglier than a blown chip or some other hardware problem, but I don't know what else to test or do. Suggestions welcome :)

Pete

[Pete Brown]

And now, it's suddenly working! Hmm. Badly seated isolator maybe? Solder joints look fine.