Core doesn't seem to recieve MIDI.

[tobamai]

Hi guys,

  I ordered a midibox core module (along with a handful of other items) from SmashTV early this year. I put together the core module but found I didn't have time to invest in the project because of class and work (I'm a college student). I'm just getting back to it (finally!).

  I suspect the input side of my core isn't working, it doesn't send any feedback when trying to upload an application. I want to make sure it works right before I start assembling other modules.

  Like I said, it's from SmashTV, it's a Core_R4D board with a PIC 18F4620 (marked as preloaded with BSL v1.2B and MIOS v1.9F, it should be Device ID 0). I'm trying to upload revision_id_v1b's main.hex just as a test.

 

  So here's what I've done: (is there anything I've missed or any conclusions I've jumped to that I shouldn't?)

 

  I'm using MIOS studio. I sent main.hex down the cable and back through a loopback without any data errors (I took the time to make sure the input matched the output exactly, because that's come up a couple times on the forum). This makes me confident the interface is not the problem, nor the software settings.

Input Log:

00000058330583 ms | Sysex message: F0 00 00 7E 40 00 02 0C 00 00 20 43 7B 63 1F 04 23 5E 19 78 22 3D 71 4F 42 15 6F 0C 7C 11 3E 78 67 61 3E 77 46 3E 0C 3F 3C 33 70 64 3B 63 1F 06 17 5E 19 78 31 5D 71 4F 43 13 6F 0C 7C 18 2E 78 67 61 41 77 46 3E 0B 7F 3C 33 70 60 3B 63 1F 04 03 5E 19 78 20 3D 71 4F 42 05 6F 0C 7C 10 3E 78 67 61 44 77 46 3E 0C 1F 3C 33 70 42 3B 63 1F 04 17 5E 19 78 21 5D 71 4F 40 24 00 00 00 02 20 00 00 00 12 00 00 00 01 10 00 00 00 09 00 00 00 00 48 00 00 00 04 40 00 00 00 24 00 00 00 1F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 78 38 F7
00000058330865 ms | Sysex message: F0 00 00 7E 40 00 02 0C 20 00 20 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 78 60 F7
00000058331171 ms | Sysex message: F0 00 00 7E 40 00 02 0C 40 00 20 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 78 40 F7
00000058331459 ms | Sysex message: F0 00 00 7E 40 00 02 0C 60 00 20 09 00 02 20 00 48 00 12 00 04 40 01 10 00 24 00 09 00 02 20 00 48 00 12 00 20 5D 41 37 41 5C 0E 7B 1B 46 30 77 5D 5D 1E 76 05 5E 04 00 3A 11 6C 0B 3C 1E 29 77 78 1D 76 37 3F 61 6F 3B 38 7E 0E 7C 1B 41 10 07 57 1E 06 78 02 20 0F 2E 3C 0F 70 7C 1A 5E 28 70 1D 21 18 76 05 5E 00 32 42 31 6C 0B 3C 16 00 71 13 58 16 78 01 6A 07 78 2C 49 6C 0B 3C 00 65 03 7C 16 24 76 05 5E 01 10 00 00 0C 29 19 2E 66 4B 4D 52 6F 37 08 09 14 21 68 24 00 09 00 02 20 00 48 00 12 00 04 40 01 10 00 24 00 09 00 02 20 00 48 00 12 00 3F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 78 60 F7

Output Log:

timestamp [unknown] | Sysex message: F0 00 00 7E 40 00 02 0C 00 00 20 43 7B 63 1F 04 23 5E 19 78 22 3D 71 4F 42 15 6F 0C 7C 11 3E 78 67 61 3E 77 46 3E 0C 3F 3C 33 70 64 3B 63 1F 06 17 5E 19 78 31 5D 71 4F 43 13 6F 0C 7C 18 2E 78 67 61 41 77 46 3E 0B 7F 3C 33 70 60 3B 63 1F 04 03 5E 19 78 20 3D 71 4F 42 05 6F 0C 7C 10 3E 78 67 61 44 77 46 3E 0C 1F 3C 33 70 42 3B 63 1F 04 17 5E 19 78 21 5D 71 4F 40 24 00 00 00 02 20 00 00 00 12 00 00 00 01 10 00 00 00 09 00 00 00 00 48 00 00 00 04 40 00 00 00 24 00 00 00 1F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 78 38 F7
timestamp [unknown] | Sysex message: F0 00 00 7E 40 00 02 0C 20 00 20 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 78 60 F7
timestamp [unknown] | Sysex message: F0 00 00 7E 40 00 02 0C 40 00 20 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 78 40 F7
timestamp [unknown] | Sysex message: F0 00 00 7E 40 00 02 0C 60 00 20 09 00 02 20 00 48 00 12 00 04 40 01 10 00 24 00 09 00 02 20 00 48 00 12 00 20 5D 41 37 41 5C 0E 7B 1B 46 30 77 5D 5D 1E 76 05 5E 04 00 3A 11 6C 0B 3C 1E 29 77 78 1D 76 37 3F 61 6F 3B 38 7E 0E 7C 1B 41 10 07 57 1E 06 78 02 20 0F 2E 3C 0F 70 7C 1A 5E 28 70 1D 21 18 76 05 5E 00 32 42 31 6C 0B 3C 16 00 71 13 58 16 78 01 6A 07 78 2C 49 6C 0B 3C 00 65 03 7C 16 24 76 05 5E 01 10 00 00 0C 29 19 2E 66 4B 4D 52 6F 37 08 09 14 21 68 24 00 09 00 02 20 00 48 00 12 00 04 40 01 10 00 24 00 09 00 02 20 00 48 00 12 00 3F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 7F 78 60 F7

  When I do connect the core to my MIDI interface I get one upload request right away and nothing after that. This makes me confident MIOS is present (if it wasn't I should get an upload request every two seconds). When I unplug the power I sometimes get a system reset message (about every other time).  

00000057160930 ms | Sysex message: F0 00 00 7E 40 00 01 F7
00000057162727 ms | [FF] System Reset

  So at this point I suspect the MIDI input side of the core module isn't working. The output side appears to be working as I get one upload request. It's worth mentioning that I don't have an LCD hooked up right now (so there's less to go wrong), but when I do it displays the copyright notice followed by the "Ready." message. I think that if there was a problem with the power supply the core would reset and I would receive multiple upload requests.

  Does it sound like I'm on the right track? I'm going to move on to the MIDI troubleshooting page from ucapps and skip down to Test In1. Since I do get an upload request string, I'm not going to post Test Prog1 - Test Out2 (they all passed, I don't think there's anything relevant to post).

 

  Test In1: All three resistors are correct. Visually inspected and tested with DMM.

  Test In2: Polarity of the MIDI plugs is correct, swapping polarity does not help.

  Test In3: LED lights, but does not flicker while MIDI is sent to the core.

  Test In4: Should be able to skip, LED lit in Test In3. LED lights when connect to IC2:6, but still doesn't flicker on data transmission. LED lights when connected to IC2:8, but obviously doesn't flicker on data transmission.

  Test In5: LED flickers on when data is sent to the core. Went ahead an double checked the polarity of the diode both visually and with a DMM, looks good. I've already checked the MIDI plugs, the sockets are soldered straight onto the board so there isn't much room for error.

  Test In6: LED stays lit, regardless of grounding M-. What does this mean?

  Test In7: 5v open and .037v closed. This is less than the .1v that's expected, does this along with Test In6 indicate a bad optocoupler?

  Test InOut1: No data returned. (by the way, this test doesn't specify if the core should have power or not. I believe it should, but I tried it both ways.)

  It looks to me like the optocoupler is the culprit, but tracking down another here is a bit of a drive. I wanted to get a second opinion before I drive out to get a replacement. Also, how bad of an idea is it to try to bypass the optocoupler by jumping J13's M- straight to the PIC's RX pin? Not as a solution, but just to see if the optocoupler is actually what's bad. My understanding is that it's there to protect the PIC from potentially damaging voltage on the MIDI cable.

[stryd_one]

Now THAT is a troubleshooting post!!!! You get a fricken gold star man. All newbies, take note!!!

You're totally right about everything. It's the opto. When you go for the long drive (sorry about that) grab a few. They're tetchy little buggers.

Wow you made that easy! Thanks!

[tobamai]

Thanks for the quick reply stryd, that's exactly what I needed to know :D

[tobamai]

The follow up: picked up some new optocouplers today and the first new one in worked perfectly. :D I'm pumped, I've wanted to work on this for a while now and I've actually got something started now.

[nILS]

[me=nILS Podewski]starts singing: [/me]

"The optocoupler is the cause,

it always is, it always was,

replace the opto swift and quick,

beat the old one with a stick..."

[TK.]

Could you please try the "bad" optocoupler with a lower pull-up value for R6?

Proposal: solder a 1k resistor in *parallel* to the 1.2k resistor (leads to ca. 550 Ohm, and you don't need to desolder the 1.2k resistor)

It would be interesting, if the MIDI In is working thereafter?

Best Regards, Thorsten.

[stryd_one]

Oh, crap, I forgot about that!

FYI dudes, TK is referring to a hardware design flaw in some midi interfaces, which can be worked around by using the lower R6 value as mentioned. It's rare, so I forgot it. Sorry!!

[tobamai]

Thorsten, I popped the "bad' optocoupler back in and soldered a 1k resistor in parallel with r6 (1.2k). I loaded up MIOS studio and had similar results to before, I can send whatever I want and nothing seems to get through to the core.

Test In1: All resistors are where they should be, r6 now measures 535 ohm.

Test In2:MIDI plug polarity is okay

Test In3: LED lights, but does not flicker.

Test In4: LED lights in both positions, does not flicker in either.

Test In5: LED flickers when data is sent.

Test In6: LED lights, but won't flicker if M- is grounded.

Test In7: Still 5v open, 0.037v closed (this hasn't changed)

Test InOut1: Regardless of what or how much data is sent down the line, nothing is returned.

I also tried Test In7 with a 1k ohm resistor in parallel with the 1.2k ohm resistor between Pins 6 & 8 (measured at 536 ohm): 5v open and .071v closed.

I'm using a Korg padKontrol as my midi interface.

Thorsten, thank you for your hard work and effort into this project. :)

(edited: sorry, originally typed ".0071v closed", fixed it to ".071v closed" -- 71mv, not 7mv)

[TK.]

Thanks for the input! :)

Best Regards, Thorsten.