eptheca Posted February 28, 2017 Report Share Posted February 28, 2017 SEQ V4 (STM32F4) 092 MIDI OUT 4 is not working with MB SID. All other MIDI OUT from the MIDI_IO modules and the two Quad IIc are working fine with the MB SID, but for some strange reason not OUT 4 I have tested it with both MIDI-OX and Send SX, and normal MIDI messages are sent like clock and note on and off. Is there a reason that the UART for MIDI OUT 4 should not work with MB SID? I have 4 different MB SID V2, 2 are sammichSIDs and I have the same problem with all. They don't work on MIDI OUT 4, but work fine on all the other OUTs, and other synths seem to work on OUT 4, and the MIDI messages looks fine. I have even tried with a different DISCO board, and checked all connections with a multi meter. Same problem and no bad connections. ????? I just don't get it Any suggestions anyone? Cheers Hal Quote Link to comment Share on other sites More sharing options...
ilmenator Posted February 28, 2017 Report Share Posted February 28, 2017 Have you tried earlier revs (i.e. before 092)? If you find that earlier versions work, then it sure is a software bug. I remember that some MIDI outs that are based on 3.3V are problematic with some MIDI gear that expects the "regular" 5V sources (this seems to be an issue even though MIDI is essentially a current loop). Maybe there are some tolerances between the Outs on your board that you hit? Quote Link to comment Share on other sites More sharing options...
eptheca Posted February 28, 2017 Author Report Share Posted February 28, 2017 I have tried 088 as well, and it's the same problem, so I don't think it's a bug. I thought the MIDI OUTs where 5V? Quote J 11 E "This port provides four MIDI IOs at ca. 5V level (the pin is configured in open-drain mode, so that a resistor connected between the MOx pins and 5V can pull the output level to 3V or 5V. Normally this pull-up resistor is not required if an opto coupler is used at the receiver side) Interface to the MBHP_MIDI_IO breakout board." What is this pull up resistor that is mentioned here? Is this something I should add? The strange thing is that it only affects OUT 4, and only MB SIDs Is it possible to measure the output with a multimeter? Quote Link to comment Share on other sites More sharing options...
latigid on Posted February 28, 2017 Report Share Posted February 28, 2017 R5 and R10 are the output pullups. As Il said, the voltage is not as important as the current, which I believe is moreso configured on the opto side. Some hacks that spring to mind: Separate the power/grounds of the devices. With an optoisolated input, this shouldn't be a problem, but often loops can cause issues. Try to buffer O4 through another MIDI device, if it works then the problem is electrical. Disable your second quad I2C module by defining fewer ports in the SEQ app (and disconnecting the second module). It could be that the increased latency causes timing mismatches. Quote Link to comment Share on other sites More sharing options...
eptheca Posted February 28, 2017 Author Report Share Posted February 28, 2017 7 minutes ago, latigid on said: Separate the power/grounds of the devices. With an optoisolated input, this shouldn't be a problem, but often loops can cause issues. Do you mean that I should connect the two power supplies to different wall sockets? The power supplies are not earthed/grounded. 11 minutes ago, latigid on said: Try to buffer O4 through another MIDI device, if it works then the problem is electrical. I'll see if I can find a unit with MIDI thru. If it works, and the problem is electrical, what does that mean? 1 hour ago, latigid on said: Disable your second quad I2C module by defining fewer ports in the SEQ app (and disconnecting the second module). It could be that the increased latency causes timing mismatches. OK, that should be easy to test Thanks :) Quote Link to comment Share on other sites More sharing options...
latigid on Posted February 28, 2017 Report Share Posted February 28, 2017 Just now, eptheca said: Do you mean that I should connect the two power supplies to different wall sockets? The power supplies are not earthed/grounded. Do the SEQ and SIDs share the same power rails (I guess not, as one is +5V and the other is +9 or so). They will be electrically isolated if you have separate transformer-based PSUs Just now, eptheca said: I'll see if I can find a unit with MIDI thru. If it works, and the problem is electrical, what does that mean? Not sure, maybe an issue with the STM pin? Just now, eptheca said: OK, that should be easy to test A long shot, as you're not even using the Quad I2C, but it is "pushing the limits" to have double quads. Just now, eptheca said: Thanks :) Good luck! Quote Link to comment Share on other sites More sharing options...
eptheca Posted March 1, 2017 Author Report Share Posted March 1, 2017 Ok, done some testing. MIDI thru makes no difference, same result. When I measure between M+ and M-, on all other MIDI OUT pins its about 0,9V, but on MO4 its 2V. This must have something to do with it. Does anybody know why this is? Is it a bug/fault or by design? Can it be changed? I guess it's not a problem for most situations, and my computer can read the MIDI messages, but for some uses like MB SID it's a problem. Quote Link to comment Share on other sites More sharing options...
ilmenator Posted March 1, 2017 Report Share Posted March 1, 2017 Sounds like a faulty resistor R8 or R10, or wrong value installed? Unpower the unit and measure resistance across R8 and then R10, both should read 220 Ohms. If that doesn't help, check resistance between M- on J6 of the MIDI IO board and pin PC12 on the STM32F4 board - this should also be 220 Ohms. These errors are a pain to find the root for, but it's better than having to search for an error that only shows every now and then... Quote Link to comment Share on other sites More sharing options...
eptheca Posted March 1, 2017 Author Report Share Posted March 1, 2017 I have checked that :( The values I got are straight from J11E on the STM32F4 Core with a 220 Ohm resistor from Vd and one from MO4 (and the other 3 MIDI OUT) I have even tested 3 different DISCO boards with different revs. The MIDI OUT 4 from UART5 on PC12 is "hotter" than the other 3 I wonder if this is because it shares pin with this on-board function: PC12 CS43L22 (Audio DAC) SDIN TK, could you confirm / explain this when you have time :) Quote Link to comment Share on other sites More sharing options...
eptheca Posted March 17, 2017 Author Report Share Posted March 17, 2017 Could someone please measure the MIDI OUT 1-4 on their STM43F4 Core or MIDI I/O module, and see if they get the same values I get? Quote When I measure between M+ and M-, on all other MIDI OUT pins its about 0,9V, but on MO4 its 2V. Cheers, Hal Quote Link to comment Share on other sites More sharing options...
eptheca Posted October 27, 2017 Author Report Share Posted October 27, 2017 I still have a problem with this. TK, have you ran into this? Cheers, Hal Quote Link to comment Share on other sites More sharing options...
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