Trying to understand the schematics

[Goldie]

I'm not 100% sure what you mean about removing R1-R8. I asked to move resistor because it would be in logical position(for me at least). If i look finished PBC i dont understand thing, but now its easy to see. 22 inputs each going to 100R, going to 2 diodes, going to either 4051 or atmega. Sure if you have expirience you dont need that, Aaron did it in one night, read schematics and adapted design, it would take me days

We are thinking about same things . I think keyword would be compact. But guys discused this in other thread. Take a look at keyboard and ISP connector. If you remove those 4 resistors you can use 5pin connector for both keyboard and ISP, you put resistors on cable.

On 32 input as far i can see connections are little different. Do you have schematics for that?

[dmitri]

I had exactly the same question : I started building the analogue board and the digital board on the same strip board...

In this configuration, I guess that resistor R1 to R8 can be removed as there is no analogue connector.

My next question is :
As I'm building a 32 input version (with 4 * 74HC4051N)....that should be future poof (I should still have sufficient room on the strip board to cram in 32 more inputs), I won't use the pins PA-4 to PA-7 of the atmega chip.

You're risking not to be able to run MegaDrum for unknown length of time. I have not yet released 32 inputs firmware version.

So, should I connect a 100 resistor to those pins that I won't use to protect against static electricity anyway ?

If you do it on one board you can remove 100 Ohm resistors between Atmega and 4051's.

On a side note, I'm wondering a few things about the programming cables :
Wouldn't it be better to use regular serie or parallel cables and put the wiring on the digital board/usb board...instead of in the cable....

That way, we wouldn't have to modify the cable.

You're doing it on a stripboard so you can do it just as you described.

[Lakedaemon]

mmhh....

If I build a 32 inputs analogous board and if I program the atmega32 with the 22 inputs firmware,
won't 16 inputs out of my 32 work ?

If it doesn't...well...I did a bit of assembly programming in my youth....I might have a go at programming the atmega32...(it would be fun...probably..and I love challenges)

In my opinion, building the (working) hardware part of megadrum is much more scary than building the software part ^_^

I just soldered a Dil 16 socket, 8 R100 and 8 Bat85 to my strip board and I already feel exhausted : I have got to route the signals in a 14*8 holes rectangles with a pitch of 2.5mm....(and I still got to solder the other 8 diods)

I learned a lot about soldering and un-soldering today...

[dmitri]

mmhh....

If I build a 32 inputs analogous board and if I program the atmega32 with the 22 inputs firmware,
won't 16 inputs out of my 32 work ?

No, they won't.

If it doesn't...well...I did a bit of assembly programming in my youth....I might have a go at programming the atmega32...(it would be fun...probably..and I love challenges)

It'll be interesting to see! But imagine you're in the middle of doing this(and it's not like a couple of hours) and out of the blue I release 32 inputs firmware version. Won't you regret spending time on writing your firmware?:)

In my opinion, building the (working) hardware part of megadrum is much more scary than building the software part ^_^

I just soldered a Dil 16 socket, 8 R100 and 8 Bat85 to my strip board and I already feel exhausted : I have got to route the signals in a 14*8 holes rectangles with a pitch of 2.5mm....(and I still got to solder the other 8 diods)

I learned a lot about soldering and un-soldering today...

With some practice building first an Analogue board for 22 inputs version now, and then, when I release a firmware, building two Analogue boards for 32 inputs version will require much (and I mean MUCH) less time than writing your own firmware. But good luck anyway!:)