My future megadrum module.

[Lakedaemon]

Greetings.

This is just a thread where I'll post my progress in building the megadrum module :

I ordered the parts from GoTronic (I'm french)

Following is the components I'll use and their price.

To build the boards (was much too expensive to go the PCB way) :
ECS1 CARTE EUROPE PASTILLES RH 2x5.40=10.80€

For the Digital Card : 14.56€

ATMEGA32-16PU MICROCONTROLEUR ATMEL RH 1x6.40=6.40€
SUP-40L SUPPORT LYRE RH 1x0.37=0.37€
XT-16.000M QUARTZ HORLOGE HC49/U RH 1x1.50=1.50€
6N138 OPTOCOUPLE. GRAND GAIN RH 1x1.00=1.00€ (this looks like it's for isolation)
SUP-08L SUPPORT LYRE RH 1x0.08=0.08€
USB-B EMBASE USB-B RH 1x1.10=1.10€ (this is for powering the digital board and the usb communication)
RES.1%.6K2 5 RESISTANCES 1/2W 1% 1x0.30=0.30€
S-1.0MH SELF MINIATURE AXIALE 1x0.60=0.60€
1N4148 DIODE 75MA 75V 1x0.06=0.06€
RES5%.220R 10 RESIST. CAR. 1/4-5% RH 1x0.15=0.15€
RES5%.100R 10 RES. CARBONE 1/4-5% RH 3x0.15=0.45€
RES5%.330R 10 RESIST. CARBONE 1/4-5% 1x0.15=0.15€
RES.5%.6K8 10 RESIST. CARBONE 1/4-5% 1x0.15=0.15€
RES.5%.4K7 10 RES. CARBONE 1/4-5% RH 1x0.15=0.15€
RES.5%.10K 10 RES. CARBONE 1/4-5% RH 2x0.15=0.30€
PB545 PRISE CHASSIS 5BR 45DEG 2x0.90=1.80€ (this is for midi in/out...maybee I don't need those as I'll build the optional synthex true usb/midi board)

For the Analogue board : 27.70€

74HC4051 MULTIPLEXEUR 8 CANAUX 2x0.45=0.90€
CG213 JACK CHASSIS ST 6.35MM 20x0.90=18.00€ (some of those jacks will be used in the Ecymbals....you never have enough jacks...very usefull stuff)
BAT85 DIODE SCHOT. 0.2A 50V RH 44x0.20=8.80€ (that's a lot of diodes, what are their purposes ?)
Damn it looks like I forgot the support for the multiplexers.....

For the Keyboard (4€) :

R1826B BP TRIANG. 1P OFF-(ON) RH 4x1.00=4.0€

For Synthex true USB midi optionnal card : 21.10€

PIC18F2550I/P MICROCONTROLEUR USB RH 1x11.50=11.50€
SUP-16L SUPPORT LYRE RH 1x0.15=0.15€
XT-12.000M QUARTZ HORLOGE HC49/U RH 1x1.20=1.20€
CER-100N CONDENSATEUR CERAMIQUE 10x0.10=1.00€
CER-22P CONDENSATEUR CERAMIQUE 10x0.05=0.50€
CM-1000N CONDENSATEUR MULTICOU. RH 2x0.55=1.10€
RES.5%.3K3 10 RES. CARBONE 1/4-5% RH 1x0.15=0.15€
CM-470N CONDENSATEUR MULTICOUCHES 1x0.50=0.50€

For clean connections between cards (didn't know what to use) : 8.65€

MH100 CONNECTEUR HE-14 1X36 PTS 1x0.60=0.60€
FH100 CONNECTEUR FEMELLE RH 1x3.70=3.70€
HE10BD-2X8 HE10 BP MALE DROIT 2X8 RH 2x0.70=1.40€
HE10BD-2X17 HE10 BP MALE DROIT 2X17 1x0.80=0.80€
HE10F-2X8 CONNECT. HE10 FEMELLE RH 3x0.55=1.65€
HE10F-2X17 CONNECTEUR HE10 FEMEL. RH 1x0.70=0.70€

For The LCD (10.39€)

K010AMP POTENT. LINEAIRE ECO 10K 1x0.45=0.45€
B164A BOUTON ALU 16MM 1x0.90=0.90€

2*16 blue LCD bought for 9.61€ on ebay from this guy
cheap LCD
(by the way he sells a 4*20 blue lcd too, for around 30€ including shipping costs...can the atmega32 use this ?)

Total : 194.42-93.45=100.97€

Beyond this point, the costs are actually investments into developping/building tools!

Tools :
ESP012/100 100GR SOUD. 1.0MM SANS PB 1x5.15=5.15€ (for soldering)
CBH5 PLIEUR DE COMPOSANTS 1x1.20=1.20€ (
908T301 JEU 2 BRUCELLES ISOLEES 1x2.75=2.75€
HT214 PINCE A SERTIR HE10 1x19.30=19.30€ (for the HE10 connections)

For Programming :

CABLE-146 CONVER. USB-RS232 1.8M RH 1x19.50=19.50€
CABLE-144 CONVERTISSEUR USB-PARAL. 1x21.70=21.70€
(I have no Serial ports nor lpt ports on my newest computer, only usb. As I have an old computer somewhere with lpt and serial ports I could have avoided spending this money but It would have made development cumbersome, I chose comfort !)


To build E-cymbals (cheap, larger and hopefully better than the commercial ones that are priced in the 250€ish euros)

DP035 DISQUE PIEZO 35MM 2.9 KHZ 5x1.20=6.00€
(the heart of a E-Cymbal Pad !)

GRAPHIT33 AEROSOL CONDUCTEUR 200ML 1x11.90=11.90€
EPKM24 EPOXY BI-COMPOSA. 24ML RH 1x5.95=5.95€
(I'll use this to build tape switch to get edge/bell/choke functionnality on my cymbals)

Shipping costs : 8€
GRAND TOTAL : 194.42 €

[dmitri]

Greetings.

This is just a thread where I'll post my progress in building the megadrum module :

I ordered the parts from GoTronic (I'm french)

Surely you didn't try make it cheaper:)
Just an example:
Atmega32 - 3.60€
Crystal - 0.40€

Anyway, good luck and keep us posted!

[Lakedaemon]

Indeed !
As this is my very first dab at serious electronic, I lack the experience...but I'm already learning :

It may be preposterous to say that but I wouldn't be surprised if the most difficult part in electronics
was the "Shopping and looking for cheap parts" bit...

It took me like 3 hours to order the previous parts from gotronic
(you have to browse through their categories and find each part after the other...it took ages and many clicks).

And when you divide your order between different suppliers, you have to balance the savings and the shipping costs.
You soon bump into the law of diminishing return when you have more than 3 suppliers (for a project the scale of megadrum).

Now, instead of ordering everything first in Gotronic and then getting the lcd screen on Ebay, I should have done the opposite :
Buy whatever I can on from the same Ebay supplier and then turning to Gotronics for the rest....(oh well...let's do it next time).

On a side note, when megadrum's project will be more mature, it might prove of interest to sell megadrum kits (I would have bought one).
The kits seller would make a profit and spare the megadrums builders the pain of looking for parts and suppliers (and of forgetting parts)....
(I understand the purpose of kits now....^_^).

I went for a deluxe version of megadrum (with keyboard, lcd, true usb midi board and lots of jacks), that's why it is a bit expensive on my list.
I guess that you could build a bare megadrum (with edrum monitor) for less than 40 €(or less than 20/30€ if you do have spare parts lying around, but I don't...next time I'll).

Actually, building megadrum is just one step of my grand scheme to get at a reasonnable price an high quality electronic drum set, of better than the 5000€ sets from Roland in the following criteria :
a) Better sound quality, more kits, more customability, better effects, evolution possibilities (BFD2)
b) Better hardware (MDS12 with Gibraltar hardware instead of Roland, larger pads, larger cymbals)
c) More pads, more inputs. I'm planning to have at least 6 toms and 5 cymbals...I might add a second Kick...and others cymbals (another snare would be overkill ^_^) to get something allong this :

d) Better "remote" interactions : there are some stuff that are a bit disatisfaying with the 1600€ overpriced TD20.

Trying to realize the grand scheme, I managed to :
1) buy a TD20+3 Roland pads+3 Roland Cymbals+an Acoustic to Electronic kit for 1850€on ebay
2) Buy a mds 12 rack for 290€ on ebay
3) Build 6 dual trigger Pads (for around 40€ maximum each)
3') have fun and play the drums !

And my next steps are :

4) sell on ebay the stuff I don't need (I'm in the mist of doing just that...the pads and the acoustic to electronic kits will go first)
5) Build decent three-zones chokable cymbals for 30€ each (don't know yet if I will succeed with this one)
5') sell the Roland cymbals
6) build megadrum
6') if megadrum+BFD kicks the TD20 in the nuts, sell the TD20 !

7) build more things and try my hand at electronic (a megadeluxe version of megadrum would benefit from pots to set the volume, tempo tick, remote control of comp apps, etc...^_^)

So...going from 4) onwards, everything I buy is actually decreasing my costs.... ^_^

Well...ok, now, I shut up and just wait for my parts to arrive. ^_^

[Lakedaemon]

I received my parts today....(It took weeks to arrive because the french packet delivery service zeroed)

And my first reaction was : Damn...the board is really small !

I can cheat with the board by soldering every two holes instead of every hole....

But how am I going to manage that with the Atmega pins ?
They are really close...and I don't even know if it's possible to solder so tiny spots with my soldering iron...

This is going to be tough...

[Lakedaemon]

ok...just tried to solder one pin on the board and I somehow managed it....
This is precision work...and the smallest blunder will have dire consequences (I suck at unsoldering)...

The board I'm using are 16cm*10cm europa form factor with holes every 2.7mm...

Now...I got to adapt the schematics to this board and try not to blotch the sold(i)ering work ^_^.

I would love to produce a board half as beautifull as Synthex and Aaron...but well...
Let's try to make a board that works first...

My goal is to make a 32 input (all in one digital + analog+true usb+LCD+Keyboard) boards like synthex did.
As I lack some parts (support for multiplexers...diods, resistors and multiplexers as I ordered parts for the 22 input),
I'm going to make a 16 inputs analogue board first and add the next 16 inputs later on.

[dmitri]

Although people tend combine the Digital and the Analogue boards into one I'd still recommend to make them separate for these reasons:
1. 32 inputs version firmware of MegaDrum is not out yet. Who knows when I'll finish it:)
2. What will you do if I come up with 40 or even 48 inputs version?:)
3. The smaller boards the simpler it is to make them/find problems on them, especially if you're not soldering pro.

Good luck!

[Lakedaemon]

Indeed...
making separate boards has pro and cons :

Pro :
you can make simpler, smaller boards.
It is easier to make and to design.
It is an evolutive design

Con :
it increases the costs a bit
it actually takes more room than an all in one board


I was thinking along the lines that :
The LCD/Keyboard/True UsB/Midi boards won't change in the future
The only thing that is more than likely to change is the analogous board
(depending on optimisations of the firmware, you could Add some inputs).
As adding inputs require adding a multiplexer,; 16 diods and 8 resistors and wiring it to 1 DA/AN pin of the atmega32,
I was planning to only use 4 of those pins and let 4 pins free for the future...

So, If I build an all in one card athis way, I might still add some inputs in the future.

[Lakedaemon]

Although people tend combine the Digital and the Analogue boards into one I'd still recommend to make them separate for these reasons:
1. 32 inputs version firmware of MegaDrum is not out yet. Who knows when I'll finish it:)
2. What will you do if I come up with 40 or even 48 inputs version?:)
Good luck!

Theoretically, I had some questions about that :

with a 20mhz quartz, an atmega32 should have around 20 Mips
As 1 risk instruction of the Atmega 32 takes 2 clock cycles, that makes 10 millions instructions for each second.

now...musicians usually want low latency and that means less than 4 milli seconds of latency.

So that it gives Megadrum 40000 instructions to take care of the inputs (say 22, 32 doable and theoretically 40, 48, 56 or 64....might be doable if an higher latency is acceptable)
Now, 40000 instructions for 22 inputs gives you around between 2000 instructions/input (for 22 inputs) and 666 instructions/input (for 64 inputs).

As a piezo's frequency is 4.6khz for 27mm piezo (Roland meshhead), 2.9khz for the 35mm piezo (Roland Rim), it means that
in 4ms you can get between 12 and 16 "inpulses" in a 4ms span of time....

Now, I don't know what kind of algorithm you use to detect hits, to prevent false re-trigger/crosstalk, etc...
(I guess it has something to do with thresholds, maximum detection, increasing amplitude, etc..., span of time after which there is no hit detection....)
But is is definitely an interesting problem (I'm a mathematician...I love those) and it might just be a problem that can be optimised (say....if you detect a hit on 4 different inputs...there is no need to scan the remaining inputs for the next 6ms (appart if you have a drummer with additionnal limbs or that is able to hit notes faster than 32th notes at tempo 240).....
If I'm not mistaken, there might just be lots of ways to optimize and spare clock cycles utilisation.

That's for the hit detection part...the other aspect of the firmware (midi notes writing, lcd and menus...) should be pretty generic.

[dmitri]

I thought that early MegaDrum adopters would be those who are more adventurous and more inquisitive:)

[Lakedaemon]

Ok...here are my progress....

I spent hours today soldering 18 diods, 8 resistors and 1 dil 16 socket...

It was interesting : I learned the behavior of a soldering iron...
The frustration of soldered parts that get un-soldered..

And that soldering iron don't last forever....

Got to order new parts and some stuff to clean my soldering iron befeore I can go on....
Let's wait for next week....