MIDIbox Forum Community Blog List

TheProf's Blog - It's alive! (Obligatory Mad Scientist Riff)

Wed, 15 May 2013 23:30:00 +0000

The missing socket arrived this morning. Full of will power I waited until after the days work was done before getting out the now rapidly declining box of bits. Socket in, C64 PSU tested, 9V tested good, so was ready to go. Small glitch until I realised that I had to change the core ID in MIOS Studio too, then all loaded smoothly. Fitted the 6852's one pair at a time, and ran through the sound banks, with a silly grin just getting wider on my face.

Still got a minor bit of front panel work to do, (3 spacers came unglued), and a little bit of fault tracing - the mix out doesn't seem to be working, but all is good, and the only last bits I need are 4 knobs for the feedback pots.

Now a lot of reading and learning to do. This thing is a small cased sound mainframe and I want to be able to drive it as it deserves.. Love the way my Korg Kontrol 49 keyboard loops up to a lot of the front panel controls too.

So very grateful to TK and Wilba for this.

TheProf's Blog - Closer

Wed, 08 May 2013 00:09:00 +0000

Still doing more stuff for other people than myself, but got another run at the MB6582. 3 parts to get, and it turns out that the ebay seller with the displays didn't ship what he thought. I have a 'plain, vanilla' black on green display, when I thought I was getting green on black 'negative'. I'll update once it's working. I had a reasonable idea for the display wiring, and put a single-in-line cable mount socket, (the kind you crimp pins to the wire, then insert into a housing), on the cable, and a 16 pin 90 degree pin header on the display. That means the fiddly display wiring only has to be done once, and I can change displays by simply plugging another one in. Pots for feedback were from Smallbear, and are neat, small Taiwan Alphas. I used heat shrink sleeving over the soldered pins to make the wiring more robust.

I Used some salvaged 2 pin computer pin connectors, from old PC cases for the 5V connections to the power LED, and teh fan, and a 3 pin one for the audio out. I have done connectors for all the I/O and the control surface connections, so that main board could be removed safely, if I need to work on it.

I hope to run it up next week, once my next batch of work is over.

nicolas' Blog - Midi & Ecran tactile

Tue, 07 May 2013 13:42:00 +0000

Bonjour,

Je me présente, je suis Nicolás, guitariste acoustique et passionné par les possibilités du MIDI depuis mon plus jeune age, même si j'ai découvert plus tard que je ne pouvais pas brancher mon joystick sur le synthétiseur de papa

Je me pose actuellement quelques questions concernant la gestion d'appareils midi depuis un écran tactile, et j'aurai besoin de quelques renseignements pour aller plus de l'avant:

Etant donné que je me dépatouille plutot en Macromedia Flash: où trouver de la doc pour communiquer via midi?
Comme je suis nase en éléctronique: comment adapter les modules proposés par le fantastique site de uCApps pour pouvoir leur intégrer une interface tactile? Genre un convertisseur de potentiomètre virtuel en valeurs physiques...
points suivants à venir, n'ésitez pas à participer...

Voila, merci de vos réponses et de vos suggestions. A très bientôt!

Nicolás

nicolas' Blog - MIDI & Touchscreen

Tue, 07 May 2013 13:23:00 +0000

Hy! My name is Nicolas, and I'll try to translate an already posted message in french.

Im passionated on MIDI technologies since I was a little boy, even if I understood later that i could'nt connect my joystick to dads minimoog ;)

Now Im looking to develop a touchscreen interface to manage different hardware equipments, so I need some peace of information to go forward on this:

As Im rather good on Macromedia Flash: where do you think I can find information on how to communicate via MIDI protocols?
But I'm a really bad electronician: so how can i find info on to integrate to fantastic uCApps interfaces touch screen capabilities?
next points to come. Thank you for your comments!

See you very soon,

Nicolas
*

Duggle's Blog - How to Offset and Scale an Analog Input

Mon, 06 May 2013 05:22:00 +0000

When interfacing a Joystick, Modwheel or Pitchbender it is sometimes found that the voltage range on the potentiometer output is well inside the range of the Core ADC input.

This can often be overcome with digital calibration in the firmware (e.g MIDIbox KB) in some cases there is extreme loss of resolution.

Presented here is a circuit to overcome this to give the ADC the full range (in this case 0..3.3V) even though the range of the potentiometer is well inside this.

The design process is very easily done following this app note: sloa097.pdf 230.01K 12 downloads

I've done a spreadsheet to make it even easier! Scale Offset.zip 2.45K 9 downloads If you don't have MS Excel, you can use it with free tools Google Docs, or Open Office.
To use the speadsheet you enter numbers into the blue fields. The input range at the top as measured on your pot. In preparing the examples, I played with the value of Rg2 so that Rg2+R1 came close to 10k. This allowed to replace them with a 10k trimpot as in the example circuits. It was just as well, as the trimpot did require some tweaking away from the calculated values, I found.

I chose LM324 op amp as it's output goes down very close to 0V. It's maximum possible output with a Vcc=5V is about 3.5V which should be quite safe with a 3.3V Core ADC such as LPC17 MBHP Core.
There are 4 op amps in this device, so 4 scaling/offset circuits can be implemented with 1 chip.

Here's the circuit with 2 worked examples:

Here's the test (input on left, output on right) showing 3 points (Modwheel example):

Here's another test (input on left, output on right) showing 3 points (Pitchbender example):

Blatboy's Blog - Now witness the firepower of this fully ARMED and OPERATIONAL battle station!

Sat, 02 Mar 2013 17:30:00 +0000

It's been a while since I've been able to work on any electronics projects, and while I've been using my MB-6582 in the studio at work, I've been so slammed that I I've not been able to finish my last touches. (Filter pots, mix out, power LED... stuff like that)

Starting next Tuesday, I'll have at least one recording session every week in my studio until sometime around mid 2014. Being that I'm already so slammed, my life, as far as my "hobby" projects go, will be over, for all practical purposes, until then. Therefore, I thought I'd try to get these last few touches installed before the onslaught of work starts.

I'll admit I've been dragging my feet a little on this. My box never really worked that well. Notes would stick, cores would randomly go offline (especially if I had more than 2 cores installed) I could use it in the studio, (if it did something freaky, I'd just re-record) but it wasn't reliable to use in a live performance...which was my original inspiration to build this. It was suggested that a nice new linear power supply would be the fix. I don't have the chops at the moment to design and build one of those, and with my new job, I feel I won't have the time to learn... so I figured I'd just have to live with a MB-6582 with some intense personality quirks (much like it's owner) and not use it in a live performance situation. I've certainly learned a lot and had a blast building it, so it wouldn't be a total loss.

Last night as I was preparing to cut some ribbon cable for the remaining filter pots, I noticed that the J1_SID1 and J2_SID2 jumpers were set for 12V. I'm rockin' 8580's! I had a really good feeling that I had found the problem!

Initial testing proves correct. It seems to be working better than ever. I still need to test with a full load of 8 SID chips in it, but it's working great with four chips now. Hopefully the fact that I've been using it for the last 6 months or so with the incorrect voltage on SID1 hasn't damaged the first two SIDs. I don't typically leave it on for very long at a time (the longer it was left on, the more quirky it used to act) so, maybe I'm cool.

This was yet another somewhat embarrassing oversight on my part. (This blog and my posts are chunk full of those.) Well, maybe my willingness to publish my mistakes will help someone troubleshooting in the future.

I will eventually replace the old C64 power supply by building a linear power supply. I want my SIDs to last. But there is no way I'll have the time to get the expertise and do the build any time soon. However, as the old axiom goes: When you've got the time, you don't have the money...and when you've got the money, you don't have the time. Anyone feel like building me a power supply?

Sasha's Blog - I`m back

Thu, 27 Dec 2012 10:44:00 +0000

I`m back after long time out of MB community and doing electronics in general. I have quite a few unfinished projects that needs some attention. In most cases it is just building housings and final touches, but still a lot of work. I feel bit rusty now, but I`ll catch what I`ve missed. See you around! ;)

TheProf's Blog - Back in the Groove

Fri, 21 Dec 2012 04:51:00 +0000

Finally getting back to building music gear. Trying to do a bit every night; averaging 30% at the moment. MB6582, nearly complete. Must take the 'wooden spoon' for slowest assembly from the initial batch, but #31 is on it's way. Wired and tested the LCD, last night, only to find I'd mis-read an advert ages ago, and got CrystalFontz normal, (black on green) displays. Will go with it for now, but will probably go for Optrex when I get the chance, (they take way less current too).

Chips burning session tonight. PIC4685 all burned, MIOS Loaded and basic test done. Reading through the notes, and using MIOS studio makes me realise just how much hard work TK and others have put into this. All went very smoothly.

Started edits for my small SID box, having got the panel wiring laid out. I got lucky on ebay with some Densitron 'mini' 2x40 displays, which match some old 'Digitast' style switches I got with some scrap, so a 2x40, 10 button design resulted. I can see myself compiling that a few times before I get it right though!
Mini production line
And the results
Tested - working showing Densitron 2x40 small display.

Duggle's Blog - 4 Midi IN/OUT Ports for SEQV4L (Adding 2 more MIDI I/O)

Wed, 12 Dec 2012 23:45:00 +0000

Abstract
This article documents the hardware and software mods to provide 2 extra (4 total) Midi I/O ports on the MB SEQ4L.
The added ports use the onboard UARTs (2,3) of the LPC MIOS32 core. The underlying sequencer code supports these ports (MIDI 3 and 4), but in the case of MIDI 3, the pins used, need to be replaced as they are( were) used to drive LED matrix columns. I chose J28 to provide these LED column driver pins, unfortunately they are part of the CV output (which I don't want) which has to be disabled in the software.

Introduction
The Midi Router functionality of the MB SEQV4 (Lite and "Full" versions) allows complex and well integrated MIDI interconnection of Synths and devices. The motivation in my case was to have Sysex Librarian and PC host synth patch design avaiable using the 4 available USB MIDI ports. Suffice it to say that having an extra 2 midi ports allows me to have RC50 Looper, MBSEQ, keyboards, and 2 Virus synths all talking and editable simultaneously from my PC. Perhaps the details should go in a separate blog article.

Hardware Mods
MIDI I/O Port 4
This one is straight forward as port J4B is free.
Simply connect a 2pin header receptacle:
J4B.SC->Midi In
J4B.SD->Midi Out
Ive used a GM5 PCB for MIDI sockets, opto, etc. but can use a standard circuit built on vero board. Just copy the circuit from a core.

MID I/O Port 3
This one is a little more involved as the pins that have the UART functionality are on J15 which is used to drive the LED matrix columns on the SEQV4L.
I've chosen J28.0 to replace J5B.6 (column driver)
and J28.1 to replace J5B.7 (column driver)
Core pin J5B.6->Midi IN (black wire in picture)
Core pin J5B.7->Midi OUT (red wire in picture)

J28.SDA->J5B.6 (connector) (white wire in picture)
J28.SC->J5B.7 (connecor) (blue wire in picture)

(above) MIDI port 3 wiring NOTE TRACKS ARE CUT between black and white and between red and blue!!!!

Software Mods
\trunk\apps\sequencers\midibox_seq_v4_lite\mios32\mios_32_config.h
This enables the extra midi ports in the firmware
include the following lines (comment out conflicting #defines)


#define SEQ4VL_FOUR_MIDI_PORTS            /*switch used elsewhere to compile this mod*/
#define MIOS32_USB_MIDI_NUM_PORTS 4  /*use with bootloader 1.010 or later for proper multiport usb */
#define MIOS32_UART_NUM 4

\trunk\modules\blm_cheapo\blm_cheapo.c
This is where the column drivers port pins are initialised, including the replacement pins of J28
replace

  for(pin=0; pin<8; ++pin)
    MIOS32_BOARD_J5_PinInit(pin, MIOS32_BOARD_PIN_MODE_OUTPUT_PP);

with


  // initialize all pins of J5A and J5B as outputs in Push-Pull Mode
  //***dug*** 6 and 7 are wired to MIDI IN/OUT3 
  //these signals are generated by J28.SDA and J28.SC, 0, and 1 respectively
#ifdef SEQ4VL_FOUR_MIDI_PORTS  
  for(pin=0; pin<6; ++pin)
    MIOS32_BOARD_J5_PinInit(pin, MIOS32_BOARD_PIN_MODE_OUTPUT_PP);
  MIOS32_BOARD_J28_PinInit(0, MIOS32_BOARD_PIN_MODE_OUTPUT_PP);
  MIOS32_BOARD_J28_PinInit(1, MIOS32_BOARD_PIN_MODE_OUTPUT_PP); 	
#else
  for(pin=0; pin<8; ++pin)
    MIOS32_BOARD_J5_PinInit(pin, MIOS32_BOARD_PIN_MODE_OUTPUT_PP);	
#endif

insert

#ifdef SEQ4VL_FOUR_MIDI_PORTS  
  //J5 bits 6 and 7 are not initialised for GPIO so have no effect
  MIOS32_BOARD_J28_Set(led_row[selected_row]>>6);//put J5 6,7 into J28 0,1
#endif

after
MIOS32_BOARD_J5_Set(led_row[selected_row]);
in
s32 BLM_CHEAPO_PrepareCol(void)
This drives the replacement pins of J28 of the LED matrix column.

\trunk\apps\sequencers\midibox_seq_v4_lite\core\seq_file_hw.c (about line 860)
comment out thus:


#elif defined(MIOS32_FAMILY_LPC17xx)
  	for(i=0; i<4; ++i) {
//    	MIOS32_BOARD_J28_PinInit(i, pin_mode);
//    	MIOS32_BOARD_J28_PinSet(i, 0);
  	}
#else

The remaining changes are to stop the J28 now LED matrix pins being driven by the old CV code:
\trunk\apps\sequencers\midibox_seq_v4\core\seq_cv.c
line 70 in SEQ_CV_Init()
change

#elif defined(MIOS32_FAMILY_LPC17xx)
  for(i=0; i<4; ++i)
    MIOS32_BOARD_J28_PinInit(i, MIOS32_BOARD_PIN_MODE_INPUT_PD);
#else

#elif defined(MIOS32_FAMILY_LPC17xx)
  for(i=2; i<4; ++i)
    MIOS32_BOARD_J28_PinInit(i, MIOS32_BOARD_PIN_MODE_INPUT_PD);
#else

comment out first 3 calls to MIOS32_BOARD_J28_PinSet in s32 SEQ_CV_Update(void) thus:


#if defined(MIOS32_FAMILY_STM32F10x)
    MIOS32_BOARD_J5_PinSet(9, start_stop);
#elif defined(MIOS32_FAMILY_LPC17xx)
    //MIOS32_BOARD_J28_PinSet(1, start_stop);		***HERE***
#else
# warning "please adapt for this MIOS32_FAMILY"
#endif
  }

  // DIN Sync Pulse at J5C.A8
  if( seq_core_din_sync_pulse_ctr > 1 ) {
#if defined(MIOS32_FAMILY_STM32F10x)
    MIOS32_BOARD_J5_PinSet(8, 1);
#elif defined(MIOS32_FAMILY_LPC17xx)
//    MIOS32_BOARD_J28_PinSet(0, 1);			***HERE***
#else
# warning "please adapt for this MIOS32_FAMILY"
#endif
    --seq_core_din_sync_pulse_ctr;
  } else if( seq_core_din_sync_pulse_ctr == 1 ) {
#if defined(MIOS32_FAMILY_STM32F10x)
    MIOS32_BOARD_J5_PinSet(8, 0);
#elif defined(MIOS32_FAMILY_LPC17xx)
//    MIOS32_BOARD_J28_PinSet(0, 0);			***AND HERE***
#else
# warning "please adapt for this MIOS32_FAMILY"
#endif

Conclusion
That's it!!

nebula's Blog - Where has “nebula” been?

Sun, 25 Nov 2012 02:06:00 +0000

MIDIbox has been a big deal to me, for a long time.  While I’ve built a few MIDIbox projects over the years, I always wanted to be a bigger contributor, and there has always been something in my life to stop me.

Over the past few years my marriage has taken a big shit all over my life.  I find myself with great ideas, only unable to fully realize them because of the amount of trouble in my life, particularly because I just couldn’t seem to get along with my wife.

I am not suggesting for a moment that MIDIboxing should be more important to anybody than the sacred institution of marriage, but … sometimes people will find that their creative life is being stifled by forces like an ill-chosen partner.  Such is the case with me.

I don’t want to go too far into the gorey details here., other than to say that I have been very hot and cold with the MIDIbox community for the past 4 years or so. What I have done has been with the very best of intentions:  I have organized multiple bulk orders and I have contributed interesting designs and ideas.  But it is difficult to properly see these things to full fruition when your emotions are forever being tugged by external forces.

I’m telling you now, with mixed emotions, that about two months ago my wife and I finally separated.  While this is a sad time in my life for obvious reasons, it is also very liberating.  Finally I can tell the truth:  the reason why I was often hard to reach, and I was sometimes (very) late in delivering on stuff that I promised, is that I have been completely consumed by marital breakdown.

Sometimes it took me a very long time to ship things like knobs, after having made deals in good faith.  While I have long since straightened everything around with everybody who may have ever had issues, I never really offered any good explanation other than “personal issues”.

Well today I am glad to announce freely that I have no more personal issues.  I finally left her about 2 months ago, and I am no longer looking back.  It will still take a bit longer before I achieve the participation level I always wanted with the MIDIbox community, and my own DIY projects, I am finally able to breathe a sigh of relief. I will finally have the time to devote to these things without judgement or undue punishment.

I really don’t want to sound like I have chosen MIDIbox over marriage.  Rather, I have chosen not to be unreasonably judged with no basis or standards, by an individual with no right to do so.  This encompasses not only my “Synth DIY” activities, but also the artistic rationale that allows me to freely create.

Without trying to explain everything that has gone wrong in my life, I am offering a sincere apology to all those who unnecessarily waited months for a few knobs, and to those who have received my (attemptedly constructive) critiques on their concepts and designs without detailed followups.

I have lots to offer this amazing community, and I am saddened that the value of my verbage has been continuously compromised by my scarcity.  Little by little I will be returning in the months to come.  Once I get my new home and new workshop in order, I hope to be able to participate with more regularity and loyalty than I ever have.

In other news, my stage name is no longer “nebula”.  I have recently been working with a Canadian label who will be releasing some of my music under my actual given name: Steve Cowan.  I’ll keep nebula for forums and maybe later as a musical alter-ego, but I’m excited to finally have an opportunity to get my music out to a larger audience, under any name.  (FYI: when I join forums and find that “nebula” is already taken, I’ve been registering as “infindebula”.)

I have also started a blog site to publicize the efforts of myself and other nearby artists.  Have a look at juggernautmusic.com to see what we’ve been up to.  The site is active now, but will officially “launch” sometime over the next few months.

Thanks for listening, my fellow MIDIboxers.  I’ve always enjoyed being a part of this community, and I can’t wait to play a bigger part in the years to come.