most basic usb version

[Stienoo]

I already bought most of the component for a megadrum but I don't think I will succeed to make a PCB.
Now I want to make it on a breadboard but to start I want to make an as basic version as possible.

On the next image: http://fotos.stienoo.be/digital%20board-sch.png
I think I can just skip the red part (MIDI)
I hope I can skip the blue part, but can I use a megadrum without an LCD?

Can you guys confirm this and are there other parts I can skip?

Thanks!
Stienoo

[ignotus]

You *can* go without an LCD, but it is very helpful to have one; the hassle later of not having one is not worth it, IMO. Otherwise, when you're testing your MD to see if it works or you want to do firmware updates you'll be missing all the feedback a display gives you, particularly when doing it on breadboard, as mistakes are much more likely and harder to pinpoint. Are you using 4851 multiplexers? They'll save you much more pain than just leaving out the LCD.
You can also leave out the inputs you don't plan on using, if what you want is to to cut down on soldering.

[Stienoo]

Ok, the LCD isn't that much work to install :p
But I can skip all the red selected parts?

I couldn't find 4851 multiplexers so I have 4051 with BAT85 diodes.
Could I build the analogue board with only one 4051 IC to test if it works and then add the 3 other ones? (I think I'll build the analogue board on a prototype PCB)

Soldering is not the problem, I just don't have the stuff to make a PCB.

[ignotus]

Yes, you can skip the red part and just solder in one multiplexer and its associated parts for the time being to see if it works (someone please correct me if I'm wrong!).

Soldering is not the problem, I just don't have the stuff to make a PCB.

I built my MD on breadboard too about 4/5 years ago and it's still alive and kicking. I couldn't get the 4851's either but I used diode arrays instead of all the bat85's, using a pcb design that was quickly superseded by the more compact one with 4851's; I could dig it up if you're interested.

[Stienoo]

I've built most of the digital board and the 'most basic' analogue board, I even programmed the PIC!
But I see you have to buy the avr from Dimitri :O
I already bought one (Atmega32) and want to test my board right now!
I downloaded a zip with all hex and syx files, isn't it really inpossible to program this myself? (an older version or so?)

[ignotus]

You can program the latest unencrypted firmware into it - it's in the FAQ list (forum hardware section). It lacks a lot of features the current firmware has but it will get you going.

[Stienoo]

Ok, nice
Don't misunderstand me, I'm willing to pay for stuff like this but I want to be sure everything works!

[Stienoo]

I've completed the digital board so now I want to connect a piezo element.
As analogue board I ussed only one 74HC4051.
I think I connected everything correct (the red wire to 'pads-connector' 10 or 74HC4051 pin 1 through a resistor and the black one to GND)
When I connect my MD to my PC sometimes the fifth block of the bottom line dissapears but nothing else happens.
Is there a guide how to set up a DIY piezo pad?

[ignotus]

When I connect my MD to my PC sometimes the fifth block of the bottom line dissapears but nothing else happens.

Block? You shouldn't be seeing blocks. Did you manage to programme the firmware in the Atmega?

Is there a guide how to set up a DIY piezo pad?

There are about several gazillion guides on how to wire piezos and make your own pads - if you can't find one here you can try the diy section of the vdrums forum, there's tons of information there that you might find handy.

[Stienoo]

Yhea, as far as I understand I could just connect the black wire to the ground and the red wire to pad connector 10 for a snare.

When I turn on my MD I first gets the welcome message and after the normal 10 seconds I get those blocks (VU meter) as you can see here:
http://fotos.stienoo.be/MD.jpg
I can scrolls trough the menu so all buttons works!

When I tick on the piezo nothing happens on the screen, does this mean I have connected something wrong or could it also be because of the type of the piezo so I have to change some kind of setting?

I think I wired everything right but there always could be an error so I'll triple chek it this weekend!