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MIDI Interface


ivop

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Thx. :-)

 

If you wish I can build one for you ( I orderd three sets of pcbs from OHS park), but p&p to USA could be a little bit expensive... in fact, it was not very difficult; the problem was finding a preferably small housing that includes the pcb.

 

 

Since you created the method of interfacing the two boards via a female DB9 connector on the Realan case side, could you describe what you used for a pinout on that connector?

 

 

Front View looking into a Female DB9 Connector

1432204827_rs232_db9_f.gif

 

I figure if I copy what you did, then later we can test the new board on your system without having to make any changes.

 

I numbered the pins in accordance to J1 of your S2-board:

post-18285-0-94818000-1551994560.jpg

 

Pin 7 is connected to pin 1 (+5V) and drives the relay (Uups, I forgot the free-wheeling diode...!)

 

I´ll do a little drawing tomorrow.

 

If there is a more wise assignment, it´s no problem to change my wiring; up to now it´s an individual item ;-)

 

Sleepy

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Remind that doing the changes like I did, the "either-nor"-function isn´t available anymore!

If the external interface-board is connected to the XEL, the internal wave-board is deactivated.

If the external interface-board is not connected to the XEL, the internal wave-board is activated.

 

post-18285-0-26436700-1552025827_thumb.jpg

Switch dropped

J4 goes to a cable with male SUB D plug with pin 7 connected to +5V. (In fact, the 0.1"-header is still populated and the SUB D cable is pluggable)

 

R5 should be dropped, added at the S2-board

D2 and D3 can also be dropped

post-18285-0-40638700-1552025843_thumb.jpg

Relay K1 and D2 (protective diode) added

J1 goes to a female SUB D jack with pin 7 connected to the coil of relay K1. (in fact, the 0.1"-header is still populated and the SUB D jack is pluggable)

 

R4 (pull-up for SYNTH IN) should be added

 

Sleepy

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Sleepy thank you very much for taking the time to post the schematic mark-ups with your changes. It seems very logical to go with your pin numbering scheme. I'll start playing with a new design next week.

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orpheuswaking / venom4728a: Are we talking about the external interface only or both pcbs (external + S2-board)?

 

I did only one for me, but I think I can assemble one for you, too. ;-)

 

But, as I mentioned before, postage from germany to usa is very expensive - an insured parcel with dhl is about 38€ (~$42)!

 

 

 

Sleepy thank you very much for taking the time to post the schematic mark-ups with your changes. It seems very logical to go with your pin numbering scheme. I'll start playing with a new design next week.

 

I have to thak YOU for this great 1088XEL and the accessories you´re designed / designing... this is much more effort! :thumbsup:

 

Sleepy

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Yes, price is really unbelievable... and the other services (ups, fedex and most of all the others I checked) are more expensive. I always asked me how it can be possible to order a PSU in china for two or three euro INCLUDING p&p whereas, if I send a parcel to my neighbor (ok, or to someone else in my country;-), I have to pay six euro just for postage...

 

But I found another service, a little bit cheaper: USPS asks 21€ for shipping to the USA.

 

Provided that soldering is no problem for you and you can order the required parts: Modding the housing is not too complicated: In fact, you have to do three straight cuttings for the DIN jacks, two countersunked 3mm drillings to fix the pcb, a drilling matching to the cable to the SUB D connector you used and filing at the DIN jacks (they are a little bit too high for the housing I used) / for cleaning the "saw borders".

If you have a (fret)saw to saw plastic, a (rechargeable) driller (ideally a box column driller) with 3mm drill bit with corresponding countersink and a file as well as an electronic side cutter, you should be able to mod the case. If you like to have the sticker (tinfoil with s/w printing) I can send them as letter. ;-)

 

If you want to try, I can give you detailed help how to do the moddings.

 

Sleepy

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Sleepy I think I can make this concept better and simpler. So I can still do the board with the integral DB9, but move all of the required electronics for the interface minus the DIN jacks over to it. Then all that would be required is to wire the 3 din jacks via a cable to the mating DB9. There would then be three possibilities for that side of things, either use individual panel mount DIN connectors in a box, or make a board with only the 3 PCB mounted jacks, or use inline cable mounted DIN jacks hanging from the DB9 connector.

 

I would eliminate the manual switch for the synth source select and just go with a solid state version of your relay that would connect up the synth to the MIDI-OUT when nothing was plugged into the DB9 (same as what your relay is presently doing). And I can get rid of a couple of diodes in the process.

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That sounds very good... I think we should wait with assembling until you finished doing the new layouts. I´ll update my unit, too; the slack attached relay (which needs a lot of power) with the single pinned 5V-line and the mounting of the s2-board on the subchassis not necessarily pleasures me. :-)

 

Sleepy

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Here's a preliminary schematic of what I have in mind...

 

post-42561-0-55752600-1552169524_thumb.png

 

So the only thing required to connect to J3 are DIN-5 jacks. And if you don't need MIDI-THRU, it'll only require two jacks, otherwise 3 are needed to cover all the possibilities. The /S2-OFF pin when grounded, will essentially disconnect the S2 Synth from the MIDI-OUT line. This can either be done with a switch, or a soldered jumper so that when you plug in the external DIN jacks the S2 is disconnected.

 

MIDI-THRU and the activity LEDs are buffered.

 

Also no LEDs are required in this version. Proper bias for the enable pin is provided by R1, so the LED indicators are now optional.

 

 

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Looks like a good plan. :-))

 

Some Ideas:

 

1) I´m not a musican, so I can´t judge if it make sens: Pin 3 and 9 of the DSUB are both ground; you could use one of the pins to drive an optional MIDI COM indicator LED on the external interface (connect Pin 3 or 9 to <LEDI / J2/pin 4. Then the optional LED could be optional connected to J2 or fit into the external interface.

 

2) At the interface-board, it could be usefull to let a little bit more space left behind the DIN-jacks. The jacks sold by my electronic parts retailer must be reworked because they covers some of the soldering points:

post-18285-0-56768000-1552323874_thumb.jpg

 

Not a real problem if the jacks can be modified, but when you´re doing a new layout no extra work (I think;-) and better compatibility.

 

Sleepy

 

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Good idea on routing a remote LED connection on the DB9. I will do it as a separate current limit resistor from the common AND gate output. This way if plugged into a system that is already using the remote LED, there will be no dimming.

 

Yeah the original layout was based on different DIN jacks which did not have the extended feet like the ones from Jameco. I too have been cutting off feet :grin: . That particular board was originally aimed at the 1088XLD for rear access, but has been replaced by a combination CF drive mount and MIDI DIN front panel board instead. Still be nice to keep this one to allow for the rear option, so I'll have to see if there is room for making the board a bit deeper so that the jacks will fit without modding. But it's not going to be high on my things to do list ;) . BTW, on the 1088XLD, the remote LED indication is already routed to PIN 6 on that header (J4).

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Introducing MIDI XEL II

 

post-42561-0-54450200-1553012488_thumb.png

Dream Blaster S2 MIDI Synthesizer mounts on the bottom side.

post-42561-0-97482900-1553012500_thumb.png

 

Board is designed to use this style of DB9 connector for DIN interface connection.

post-42561-0-58516300-1552693712.jpg

 

Updated Schematic

post-42561-0-81534100-1553012515_thumb.png

 

There will be a mating board for the DIN Jacks which will have a right angle male DB9 connector. So all that would be needed is a DB9 male/female cable to interconnect the two boards, or for testing they could be directly connected together without the cable.

 

Updated Design on 3/19/2019: Added additional ground pin to J2 header for audio wire shield connection if using coaxial cables.

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A suggestion for mating board/J1: Can you place solder points for a 10 pin 0.1" header at the place under the DSUB-connector, so that I can use a 0.1" header alternativ to the DSUB?

post-18285-0-58351300-1552721687.png

(sorry for poor, not true to scale drawing; I used paint to visualise my request;-)

 

If I use a cable direct soldered to the board, I can do it pluggable. :-)

 

Sleepy

 

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A suggestion for mating board/J1: Can you place solder points for a 10 pin 0.1" header at the place under the DSUB-connector, so that I can use a 0.1" header alternativ to the DSUB?

post-18285-0-58351300-1552721687.png

(sorry for poor, not true to scale drawing; I used paint to visualise my request;-)

 

If I use a cable direct soldered to the board, I can do it pluggable. :-)

 

Sleepy

 

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A suggestion for mating board/J1: Can you place solder points for a 10 pin 0.1" header at the place under the DSUB-connector, so that I can use a 0.1" header alternative to the DSUB?

 

If I use a cable direct soldered to the board, I can do it pluggable. :-)

 

I don't really see an advantage to adding the header, when a pre-made DB9 male/female cable can be bought off of eBay or Amazon for $3-4 with shipping included. And if you want to solder one end as you also suggested, no reason I can see that you can't still do that to the pads of the DB9.

 

Personally I hate building cables, so I always look at solutions that either eliminate the need or allow for an inexpensive pre-made cable to be used.

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@mytek: The possibility to use pre-made cable is a good idea; no question. This layout requires a housing with a exact matching width to the dimensions of the pcb - on the one side you have to do the cutout for the DIN-jacks, on the opposite side the cutout for the DSUB-connector.

 

I prefer a fixed cable; it can´t get lost or used for something else :-D and it´s easier to find a matching housing. I find it easy to service if the cable inside the housing is pluggable (like this)

post-18285-0-81194900-1552752823.jpg

 

and not soldered. In fact, I uses pre-made cable, too, to build my first version of the external interface board - I cut of the one end which ends in the interface board and made it pluggable.

:-)

 

I´ll check if there is a small DSUB-connector I can use instead of the PSK-connector shown above fitting inside the housing.

 

@Mathy: If you need a interface with MIDI IN / OUT only, this way you have to do one cutout in the housing; if the not populated because not needed THRU jack is in the middle, you have to do two cutouts.

 

Sleepy

Edited by Sleepy
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Why put the MIDI THRU on the outside? Usually it's in the middle.

When I was first began working on the idea of adding MIDI to the 1088XEL, I was originally thinking of limiting it to MIDI-IN and MIDI-OUT only, so I copied the 2 jack MIDIMATE arrangement where it goes from left to right, MIDI-IN, MIDI-OUT. Then later I decided to add in the MIDI-THRU jack, and just placed it towards the far left. No real rhyme or reason for making that decision.

post-42561-0-71813100-1552750277.jpg

 

Because of your post, and out of curiosity I did a quick search online and here's what I kept finding.

 

post-42561-0-72405000-1552750011.jpg

post-42561-0-59913200-1552750018.jpg

post-42561-0-23647400-1552750024.jpg

 

So it appears that several manufacturers have a different arrangement, with MIDI-THRU also on the far left, However MIDI-OUT is front and center.

 

And then there is ivop's board, which yet again is unique, with MIDI-THRU now on the far right.

 

post-20947-0-35587500-1510080962.png

 

 

Bottom line, does it really matter? Personally I would think not, so long as the connectors are labeled as to what they are.

 

Anyway to change my arrangement would just mean there would be inconsistency from what I've already done on previous boards, including the upcoming 1088XLD.

 

----------------

 

Well I guess I'll have to eat my words on that last sentence. Because when I looked back at the board and then the schematic, it soddenly appeared to me that I had mislabeled the jacks vs the schematic. So here is the reality at this point after correcting the labels...

 

post-42561-0-94829000-1552754646_thumb.png

 

It now matches ivop's jack arrangement. Such a dilemma... what should I do :?

 

I guess I could always go with what I said in the sentence before that, where so long as the jacks are labeled what does it matter :) .

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I guess I could always go with what I said in the sentence before that, where so long as the jacks are labeled what does it matter :) .

 

AFAIK there's not a standard. I always check the ports when I'm connecting devices.

 

As for my arrangement, I figured what goes in, must come thru, so I grouped those together. On the original 5x5 design, they were on opposite sides, considering it's a continuous "pipe" on which midi in is "snooping".

 

But of course, one can also argue that midi thru is an output and hence group it with MIDI out.

 

Or put it in the middle ;)

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AFAIK there's not a standard. I always check the ports when I'm connecting devices.

 

As for my arrangement, I figured what goes in, must come thru, so I grouped those together. On the original 5x5 design, they were on opposite sides, considering it's a continuous "pipe" on which midi in is "snooping".

 

But of course, one can also argue that midi thru is an output and hence group it with MIDI out.

 

Or put it in the middle ;)

 

Agreed :) .

 

But I also like consistency, so I updated both the schematic and the board layout to be consistent with the arrangement on my other MIDI designs. To see that update go HERE.

 

As a side issue, it actually produced a simpler trace layout as a result.

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Hello Michael

 

Talking about consistency, here's HARdwareDoc's MIDI-Mate interface:

 

midimate_mit_buchse_und_kabel_klein.jpg

 

:grin:

 

Sincerely

 

Mathy

 

LOL everybody has there own unique vision. Is there any information on this design? Looks like it too might be micro-controller based, but I'm just guessing by the visual.

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