Troubleshooting my Core MIDI interface

Testing/Troubleshooting
1

Hi. Apologies in advance for the newbie questions. I am currently working my way through the MIDI Interface Troubleshooting page on uCApps. I have a USB-MIDI interface and I am not seeing an upload request or getting a flicker on an LED connected to my MIDI Out port. I am stuck at the point of testing the polarity of my MIDI plugs (TEST CORE6) using this diagram:

I have a few questions/confirmations:

  1. Should the lower pin on J12 be M+ instead of M-?

  2. The MIDI in and MIDI out refer to the female MIDI sockets and not the male plugs right?

  3. Am I supposed to be testing the polarity of the plugs or the sockets?

  4. Should I be testing with my USB plugged into my PC and the plugs in the sockets or not?

  5. I am looking for positive DC voltage of pin M+ with respect to M- right?

Apologies again for all the questions but I have been stuck at this point for 4 days now. :frowning:

mbhp_core_extract_midi_plugs.gif
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2

Update:

Moved ahead to TEST CORE7: - don’t know how to test the polarity of a diode but the direction was marked on the SmashTV PCB so I’m pretty sure that’s OK.

TEST CORE8: R8 and R7=220 Ohm - checked and OK

TEST CORE9: crosslink between the core module and PC is correct

TEST CORE10: not applicable. Not getting any messages

TEST CORE11: 2200uF Cap looks to be soldered in fine.

TEST OUT1: No Good - not getting any flickering of the LED

TEST OUT2: Didn’t try but disconnected PSU on laptop and still no upload request or LED flickering.

TEST PC1: check the MIDI-Ox configuration -downloaded MIDI-OX and routing looks OK

TEST PC2: didn’t get it working with MIDI-OX SysEx view but managed to receive MIDISync timestamp and other data sent when the loopback was connnected so my USB-MIDI interface appears to be OK. I also  got a flickering on an LED connected to the MIDI out pins.

I should have mentioned that:

I am getting the ‘READY.’ message on my LCD so some of the PIC and Core appears to be working OK.

I installed the 10 MHz crystal as supplied in the SmashTV kit - TEST CORE1 -looks fine.

I have gone through the schematic and continuity and resistance checked all the available soldered connections (TEST CORE3) -all tested fine.

I have checked the Vdd and ground connections of the PCB as per the schematics (TEST CORE4 and TEST CORE5) - all fine.

I’m not sure what is meant by the TEST PROG1: 'use the verify function of IC-Prog/P18 ’ but since I bought the PIC with bootstrap loader from SmashTV it’s probably not applicable.

Am I correct in saying that there is no point in going on to testing the MIDI-In or the Opto-coupler if I am not getting the upload request or getting a flicker on an LED connected to my MIDI Out port?

Thanks in advance to anyone who can spare a few minutes to help out a hopeless newbie.  ;D

3

Diode polarity : You can test that with a multimeter. For instance by measuring resistance with a multimeter - should be 0 in one direction and infinity in the other direction. See: http://www.allaboutcircuits.com/vol_3/chpt_3/2.html

The MIDIOut (upload requests) does not go through the opto so a broken opto should still give you upload requests.

“Ready.” on the LCD means that MIOS is on the PIC. That’s good :slight_smile: But now I’m wondering, since you said you got the PIC with only the bootstrap loader on it: How did the MIOS get on there?

4

Oh dear. :-[ :-[ :-[

I believe I may have spent the last 5 days troubleshooting a problem that didn’t exist. Maybe the reason I wasn’t receiving the MIOS upload request was that the PIC already had MIOS loaded…  Doh!

I was following Thorston’s Core testing segment and when he said “The next step is to upload MIOS” I followed that procedure. I just went back to SmashTV’s website and confirmed that the PIC comes “Programmed with the bootstrap loader and MIOS”. Oh well, at least I am now intimately familiar with the Core PCB layout.  :slight_smile:

Thanks very much for the response nILS. Not only have you saved me more days of pointless troubleshooting: but now I know how to test the polarity of a diode! :smiley:

This newbie owes you ein weissbier!

5

Um, just to make sure - even with MIOS installed you should get [at least] ONE upload requests within 3 seconds after power-up.

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Thanks nILS. I’ll do some more reading and then keep plugging away until I see some sign of life.  :slight_smile:

7

Further Update:

As a result of SmashTV spending a couple of hours with me on chat I was able to confirm I am getting that single LED flicker on power-up (TEST OUT1). I also see a flicker on the input LED on my USB-MIDI interface.

TEST PC2: I’m able to get data back on a loopback set-up but the received bytes is much less than the sent. It looks like I am having problems with my USB interface. This may be the reason I don’t see the upload request (on start-up) in my In Monitor on Midi-Ox or MiosStudio.

I have tried updating the USB-MIDI interface driver as Thorsten suggests in the MIDI Interface Troubleshooting page but the windows message says I have the best one. I also lowered the Low Level Output Buffer size and increased the output delay in the MIDI-Ox SysEx configuration menu as suggested with no success.

Has anyone else had issues with these USB interfaces who might be able to point me in the right direction?

Thanks.  :slight_smile:

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What is the name of your MIDI Interface?

Best Regards, Thorsten.

9

Hi Thorsten;

Unfortunately there is no name on it. I bought it from one of the many Hong Kong vendors selling them on eBay: http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=180180954171&_trksid=p3984.cWON.m313.lVI

Their photos have been taken down but the interface cable comes with the MIDI IN and MIDI OUT plugs on one end, USB on the other and this device in the middle:

It came with nothing except these instructions.

Would you recommend going with a better/more reliable interface or to keep trying with this one? I also have an older desktop PC with a joystick port. I tried several shops but could not locate an old-style Soundcard -> MIDI IN/OUT cable to suit it. I have found one locally on the web. Would it be worth trying this approach instead?

Thanks; Ciaran.

10

It seems that it is using the standard USB-MIDI driver, so the firmware is probably buggy. I would open the case and check, if a PIC has been used - if so, I could give you an alternative firmware which works :wink:

Best Regards, Thorsten.

11

Here’s a shot of the internals of the case. Maybe you can tell me if there is a PIC in there.  :slight_smile:

How would you load new PIC firmware? Via the USB?

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No, it doesn’t look like a PIC

Best Regards, Thorsten.

13

OK, I’ll look into my other options.

Thanks for the rapid responses.  :slight_smile:

14

Update:

I bought a gameport-MIDI interface and hooked it up to a desktop PC. I got the upload request immediately after power-up every time. I was also able to display text on my LCD using the MIOS LCD Message facility on MIOS Studio.

I tried uploading the MIDIO128 application using Midi-Ox but the core still did not reboot and I did not get anything back on my Input Monitor.

I went through the TEST PC1 and TEST PC2 steps on http://www.ucapps.de/howto_debug_midi.html

Then I went through TEST IN1 to TEST IN6 and TEST INOUT1. All these tests went through with no problem.

I tried uploading the software implemented loopback test .hex file from TEST SW1. This didn’t go so well. I got the following response from MIOS Studio.

The LCD displayed a constant ‘Rebooting MIOS’ message. When I powered down and back up and ran MIDI-OX with the virtual MIDI Keyboard I got occasional messages back in the Input Monitor but they didn’t correspond to the notes in the Output Monitor. I have reloaded MIOS successfully now.

Any ideas, advice or suggestions would be much appreciated.  :slight_smile:

Thanks.

15

Hi,

the loopback test is a special firmware which cannot be uploaded via MIDI, it replaces the bootloader and therefore is only useful for somebody who owns a PIC burner.

However, although the bootloader refuses to upload this firmware… the messages are looking good! The block between 0x3000..0x30ff (the only one outside bootloader range) has been uploaded successfully. This means, that the bidirectional connection is working.

Before uploading MIDIO128, you have to upload MIOS v1.9f (can be found in the mios_v1_9f_update package within the pic18f452/midi directory)

Best Regards, Thorsten.

16

Thanks Thorsten. It’s good news that the bidirectional connection is working.

I have already re-uploaded the mios_v1_9f_pic18f452.hex file from the  mios_update_v1_9f[1]\mios_update_v1_9f\pic18f452\midi directory and I get the “MIOS V1.9f © 2007 T.Klose”  and the ‘READY’ messages on my LCD when I power up.

The next thing I do is to attempt to upload the midio128.syx file from the mk_midio128_syx\mk_midio128_syx\pic18f directory using MIDI-OX. All the 1590 Bytes of data goes out as it appears in the Output Monitor but nothing appears in the Input Monitor and there are 0 Bytes received in the Display Window of the SysEx View and Scratchpad. Also there is no reboot or change visible on the LCD.

Am I doing the right thing here?

Edited to add: I just went through the .syx file generation process using the instructions in http://www.ucapps.de/howto_tools_mbsyx.html just in case I should not have been using the midio128.syx file in the mk_midio128_syx\mk_midio128_syx\pic18f directory . I successfully modified the midio128.ini file and converted it to a .syx file with a new name. I loaded this file in the MIDI-OX SysEx tool and sent it but again nothing appears in the Input Monitor.

Any ideas would be welcome.

Thanks; Ciaran.

17

Hi Ciaran,

before uploading the MIDIO128 configuration file, you have to install the MIDIO128 application - you will find the package at the MIOS upload page.

It seems that this approach (installing MIOS -> MIDIO128 -> configuration) isn’t so obvious, therefore I will add this info to the MIDIO128 introduction page soon

Best Regards, Thorsten.

18

before uploading the MIDIO128 configuration file, you have to install the MIDIO128 application -

Thank you Thorsten. That was the key to the problem. I have spent a lot of time trouble-shooting my core when it was actually working fine. :-[

Looking on the bright side it is working now and I am more familiar with the design of the core and the associated software than I would otherwise have been. :)  I’m pretty sure this will be a good thing in the long run.

As discussed with stryd_one, when I finish this project I am planning to put together a ‘dummies guide’ to MIDIO128 in  order to document some tips and the pitfalls a complete newbie can avoid. I will run it by him for accuracy before posting it.

Anyway the bottom line is that as a result of your post I spent the last half hour watching a row of LED’s dancing around to the merry tune of ‘Morrison’s Jig’.

This has been my best MIDIBox day.  ;D  ;D  ;D

Thanks again Thorsten.

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Great! :slight_smile:

Please inform me once the dummy guide is avalable, so that I can add a link from the MIDIO128 page - It will be really helpful :slight_smile:

Best Regards, Thorsten.