/tilted/

Nope, you have the D7 pin as an output, and you set your RA0 pin as an input. Source impedance is around 2.5k for these pins, so no huge current pull.

OK. What if each core were to simply read the E->LCD pin from the other core before doing a write? Say, using a spare AIN pin? Say FM wants to write to the LCD. {Code written in "I know shxt about C" brand C} [tt]FM Core checks RAO ;(which is connected to SIDcore RD7 - E pin) RA0 returns high ;(meaning SIDcore is writing to LCD) FMcore returns without writing, does whatever else it does... RA0 returns low ;(meaning LCD bus is free) FMcore sets RD7 high FMcore writes to LCD[/tt] I guess this would all be better if it were part of the ASM driver for the LCD, right? Is this a fix? Is there any time during a core LCD write, when the RD7 (E) pin goes low?

Woudn't it be simpler to have a third PIC which takes parallel data from the 2 CORE PICs and decides for itself how to drive the bus?

The diodes would prevent damaging things, but I'm not sure that you can drive the LCD bus this way. As I say, no damage to be had, but you might need the cores to do a little polite handshaking too.

.....(sin(1))..... .....(cos(1))..... ....... 0.5 ........

I'd say that doing a prototype on veroboard is much more challenging than buying a board (or a kit) and assembling it. Well done.

Hmmm.. 75019 = $16.50 each (inc shipping) vs about $33 each+shipping... I think I'm going cold on the 8113!

So, I plan to do a SEQ and FM on one board, and as much SMD as possible (cause I'm a sucker for punishment)... I figure that I can connect pin TX of SEQ direct to pin RX of FM, no need for opto, as there are no "potential" problems. OK, so, if I also want a duplicate MIDI OUT from the SEQ without needing to do any IIC tinkering, can I simply do this: [tt] (SEQ)TX]---+--------[RX (FM) | +-/\/\/--[Midi Out 220R [/tt] Problems?

Greetings strec. Check here: http://www.midibox.org/forum/index.php/topic,11262.0.html Also, please, try the search first. (stryd_one will set the angry raccoons on you) ;)

The motion is carried. shut up stryd ;D In other news, I think the matrix board itself might end up coming in two flavours. The 75019 is a socketable PLCC-44, while the 8113 is a 100 pin LQFP. Also the 8113 has SMD bypass caps on the reverse side, under the chip itself, much like the eval board offered by AD. Why SMD bypass caps? something to do with fitting 19 caps in the space beneath a 14mm chip, with each cap "as close as possible" to the pin in question... Therefore, perhaps it would be best to offer both boards. One as a "beginners->medium", the other as a "medium->advanced" version. Analog pinouts are of course identical, and serial control will be very similar, but the 8113 has the parallel option. Of course, if NO-ONE has any objection to soldering 100pin LQFP (0.5mm/0.02" pin spacing), then maybe we don't need the 75019 version? Or if everyone objects, I guess I'll be building a different "prototype"... Thoughts?

Now here's a little subject I've been wondering about. Is there a less-than-official chat somewhere?

MFs- negatory. I say if someone wants to put motorfaders and a switchpoint matrix in the same box, they can add another core. -they'd probably need to anyway. For mixed serial/parallel control, we just need to hold on to as many free pins as we can muster.

One thing i am curious about... Why do the refund thing on the DIN module? Are you not determined, as the rest of us, to make like seven of each type of midibox, plus three or four user projects on the backburner at any time, forever? We have to keep Smash hella-busy at all times, right?

You crazy kids and your fast LFOs. I remember when the 'L' was for "low" ;) Mind you, according to the electricians, 240V household mains is referred to as "low voltage". They count anything less than 1000V as "low". -cause they're tough. :)

10k is very highly recomended. Others can work, but too high a value is a bad thing, as it creates jitter (noise) on the AIN pin, which the core is duty-bound to process and spit out as a string of MIDI values. Too low a value can put extra strain on your PSU, leading to the inevitable posts of "my core keeps resetting, I have 64 100 ohm pots and a 25uA power supply. What is wrong? ;D

I of course have no idea here, but: Is it possible to change the divider? To maybe 1536 or 768? Both significant numbers in the binary world... unfortunately the only way to ensure even divisions regardless of your time sig is to use ? ppqn. This makes your sequencer run very slowly... Edit: fixed the ?...

AD75019 layout - done. AD8113 layout - analog done, digital control - I have questions. Input buffers - done as a 16 channel, 4xTL074 layout, then re-done as a 16xTL071 layout, which allows for better power segregation between channels = lower crosstalk. Output buffers - not done yet. AD75019 and AD8113 s are fully cascadable in two axes using dual-row 2x8 pin headers. BAM. BAM again. And now the question: The AD8113 has a serial mode and a parallel mode. I'm thinking the serial mode is what we'd use the most often. Would we use the parallel mode at all? I can see it being useful for creating patches, ie one connection at a time, the serial being better for slamming an already built patch in to the chip... My query is one of MBHP pins to use. If we use J10, the easiest option is to skip 595s and plug the serial connection straight in there. But if we use parallel mode, we'll need more pins, so we'd use 595s. But using 595 pins to spit serial data into a chip is gonna take months!! Ie, PIC->(Serial to parallel via 595)->(Serial input at AD8113) Perhaps we could cascade serial data out of the 595 into the AD8113? Would this limit the number of AD8113s we could chain?

My aim at this point is to make the matrix a line-level device, intended to patch signals at +4dBu type levels. Inputs and outputs will be balanced TRS connections. I'm also considering a +6dB gain switch for unbalanced inputs.

Hi Lylehaze. Some really good stuff. I wonder if it might be a good idea to keep compatable pin headers between these projects, as they would work very well together. I think especially that combining the FX routing options of the MBMixer would tie in very nicely with a switchpoint matrix such as this. A switchpoint matrix might also be good for dropping in things like channel inserts... hmmmmmmm.

Jesus Stryd!! The suspense is killing me! You trying to give me a heart attack?? ::) maybe I need to cut back the caffeine a little bit

Holy carp! That is a very nice piece of vero work! Well done Pierrot.

The 8113 has the option to do either a full chip dump, or individual crosspoints. This option is selectable any time, using the (!Serial)/Parallel pin. - however, it is also a 100pin LQFP. The 75019 does not have this option. In any event, as a crosspoint inherently happens only on one chip, we could chose to re-load only that chip, not the whole matrix... Hi Doc. I meant to get to this earlier, but got swept up a bit... I hope you don't feel that we are completely re-inventing the wheel/stealing your thunder here. I feel that where we're at here is perhaps more like a modularisation/ re-visit of your "vicky". It was certainly no-ones intention to ignore your work. I only hope I can do it justice. :-\

Exactly. By definition, less effective. They are basically discussing turning your board into a shielded device. My concern is that this may all be fruitless if we end up ganging boards together using ribbon (=unshielded) cable. On the other hand, is all this a little overkill if the whole deal is to be mounted in a heavy steel box, connected to earth? Or would something in between be better, to take a leaf out of the RF world. Perhaps we could go for your example 2, with signal traces on board top, ground plane on board bottom, ground traces between each signal trace, and an Al lid mounted on top (a la the RF box in the C64, to use a common example) Edit: PS, re the ground plane argument... there are two basic design concepts to be taken into consideration here. 1) the ground as a sheild. 2) the ground as a 0V reference, as the "return" for an unbalanced signal. in the former, you want the ground to surround the sensitive areas of your circuit, and to be connected only where needed, ideally in one location only, or the minimun number of locations. in the latter, you want to avoid ground planes, as these are the opposite of the ideal, which is a star sheild arrangement.

I think that since the chat went down, these threads are getting stranger...