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808Micro - Control Surface




In general I don't recommend starting any project with an enclosure that is smaller than what you can fit a proto version of your project in. But my enclosure supply just about gone, so I'll use what I have. The tekbox from TEKO enclosures. (NOTE: If for some insane reason you decide to emulate this work in progress, buy a tekmar case. It's the same but bigger)


Stage 1: Planning (barely) ahead.

Since this isn't a masterpiece by the MB gods, I 'm just going to build the control surface on veroboard (protoboard) and hand wire each component. This gives me that added option of making components sit really close to each other without worrying about PCB traces. My veroboards are from RadioShack. They are pretty standard 0.05" spaced holes and have pads on one side. To make sure the control surface would actually fit in the tekox, I created a new part of the pads in Eagle and then placed each component on the grid. My LCD in this picture is from the SparkFun eagle library. I also placed an optional 4 digit 7 segment display and knobs on the layout. (If you can, always place the knobs on encoder layouts. Even if its just a circle. I have at least 3 old projects that I never use because there isn't enough space for knobs and it looks like crap)

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For all intensive purposes the 4 digit 7 segment display will probably not get populated (but its nice to have the option to put one there).

Stage 2: Sizing up the competition

As you can see in the picture below, the 1:1 print layout of the control surface fits perfectly in the recess of the top half of the enclosure. The knobs might protrude on either side of the case recess, but I'll just have to live with that.

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Still not done checking though. I've burned myself enough to know that I'll have to test fit some parts on hand to make sure this is all going to work. After testing the LCD, I realized the SparkFun 16x2 LCD pin out is off by 0.05" but the outside dimension is perfect The SparkFun display was perfect. The Displaytech LCD footprint I used wasn't. I'll adjust the part and retest the fit. In the next version, I've also rotated the swing pot 180 degrees so that I can add the record indicator led next to the shift indicator led.

Stage 3: 3D Rendering

This step wasn't even remotely necessary. I'm just playing in sketchup with 3D rendering of eagle layouts. I've modified the EagleUp script and created some new models to generate a 3D rendering of this control surface. I originally had every intention of checking this against the enclosure DXF but OKW (TEKO) didn't have one available, so this is what you get. Still makes me happy to look at it.

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This project is still very much a work in progress. At the time of this writing, I'm still planning the base PCB. If for any reason the MidiBox gods see a train wreck coming, let me know.



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I like the look of your control surface! Are you going to have enough room for your Core, DINs and DOUTs in that box?

For the past couple weeks I've been working on a small MB-808 control surface as well. My enclosure is a little Hammond box with a 6.5" x 5.5" control surface. I like to etch boards myself, so I laid out all my buttons on a single-sided board, with numerous headers to connect it sammich-style to a custom DIN/DOUT board. I've spent a lot of time laying out this DIN/DOUT board, and I think I'm going to scrap it. Too many ICs on one board combined with my home-etch design rules (FAT traces, single-sided), and it is MESSY! Plus I think I'll be 2 hours just drilling the damn thing.

So now, instead of home etching I think I'll get my board fabbed by this fine gent at Dorkbot ( http://www.dorkbotpdx.org/wiki/pcb_order ). Since I have much more PCB density at my disposal, I plan to put my buttons and LEDs on the same board as my DIN/DOUT. To fit in the available space, I will probably use SOIC (surface mount) shift registers.

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I don't want to get ahead of myself on this blog her, but this is what I've decided.

1. I don't need a MIDI IN via a DIN5 jack. I can use MIDI over USB from a GM5 or a PIC18F2550 ( I happen to have a number of spares from sample requests)

2. I will need a MIDI OUT to trigger the drum machine

3. I will only have 1 EEPROM on board

4. Unused ports like AIN and J6/J7 are intentionally left out

Therefore, I've been considering emulating the Arduino power supply via USB or the one from MeeBlip. I have some fear about using the 5v from USB directly. But USB affords me from having a massive 2200uf 16v capacitor.

From a design standpoint, I'm using .008" (8 thou) traces whenever space is at a premium and so far I have a DINx5 and a DOUTx6 on the PCB.


While the CORE, DIN and DOUT wont change much except for spacing the USB section will change a ton the DIN SIL resistors will be mounted at 90 deg on the underside. This happens to be the PIC182550 version. I don't have a 16mHz crystal, so the GM5 version is scrapped for now. I also have enough DOUTs in this version to add the BPM display so that's awesome!

But I'm also considering where I will put an expansion port. I'm also considering the 4x16 led matrix on its own PSU in a matching case.

From a fabrication standpoint, I will make this myself. I'm using the pulsar toner transfer which works surprisingly well.

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I use the Pulsar system as well and have never had success getting traces that small. You make me want to try again though - I just got my hands on a different laser printer, so maybe I'll try one more time- the "new" one is a LaserJet 4 series, the old one is an ancient Apple Personal Laserwriter 300.

Can't wait to see your finished box. Thanks for blogging!

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Dear digineural,

I'm building a small drumsequencer (MB808) myself and somewhere I found the '808 hardware config pdf' that you posted. It really helped my to find out how to wire up my machine, it worked. But I really like your modified din mapping, so maybe you want to share the .hex file?! Thanx anyway,



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OK that would be great.

My case is not so small as yours, 2 dinx4 and 2 doutx4 will fit easily so it's not a problem for me. I thought that you already recompiled the code so I could use my dinx4 for an other machine. I'll use the code as it is for now, I'll only enable the accent for the midi out, but that I can do myself. I'll post some pics when the machine is ready. Your idea looks really nice!



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