32 inputs on MegaDrum

[dmitri]

Hi,

I just wanted to give a preview of a future version of MegaDrum. It will support 32 input channels. It will be based on MegaDrum32 Digital board (no modification of the board will be required) as Atmega8 doesn't have enough memory to handle 32 channels. This version of MegaDrum will only require a different version of Analogue Board ( actually two Analogue boards, each having 16 input channels. This is the schematics for this board:

megadrumanalogue2.jpg

I will compile a 32 channels specific firmware version of MegaDrum when I have time for building this board to test it with, and this may not happen very soon since I don't like soldering that much:)

[elrules]

Do we have to build 2 of this analog board? And then connect the remaining 4 and 3 outputs of the analog connectors of one board to the other outputs of the second board? Is that the way they will work? Is this the 32 inputs version you are NOW working on? or are there changes on the board?

This is because if I'm going to build the analog board, I prefer to directly build two analog boards like on that schematic you have posted, and wait till the 32 inputs firmware is out. Am I doing right?

[dmitri]

Do we have to build 2 of this analog board? And then connect the remaining 4 and 3 outputs of the analog connectors of one board to the other outputs of the second board? Is that the way they will work? Is this the 32 inputs version you are NOW working on? or are there changes on the board?

You will need to build two these boards and with jumpers you will select which one is the first board and which one is the second.

This is because if I'm going to build the analog board, I prefer to directly build two analog boards like on that schematic you have posted, and wait till the 32 inputs firmware is out. Am I doing right?

It's up to you. You can build all analogue boards right now and only use 22 inputs version Analogue board and later switch to 32 inputs version. Or you can just wait...wait...wait:)

[robotfriend]

What do you mean "select with jumpers"? I don't understand how two analog boards, each with a 16-pin output, can both connect to a single digital board with a 16-pin input.

[Synthex]

What do you mean "select with jumpers"? I don't understand how two analog boards, each with a 16-pin output, can both connect to a single digital board with a 16-pin input.

On the first 16-pin input board you plug the J2 and J3 jumper.
On the second 16-pin input board you plug the J4 and J5 jumper.
Or you can use the 32 inputs PCB All In One too

[robotfriend]

I'm sorry, I'm still really confused. I've taken 2 electrical engineering courses in college so I have a little bit of theoretical knowledge but I've never used any PCBs or done any projects this big. I really want to understand what's going on though.

What do the jumpers do exactly? Don't they just connect pins together? How can the processor determine which signal from the drum pads is being activated, and its velocity, from only 16 pins? Does it use some sort of MUX?

I probably have too many questions...can you refer me to any documentation or books that explain this stuff?

Thanks!!

[Synthex]

What do the jumpers do exactly? Don't they just connect pins together? How can the processor determine which signal from the drum pads is being activated, and its velocity, from only 16 pins? Does it use some sort of MUX?

Jumper connect a MUX output to an analog input of Atmega.
Yes, 74HC4851, MAX4558, CD4051, ... are 8/1 MUX.

[robotfriend]

ok...I think I get it...I think...thank you!

[xploited]

What do you mean "select with jumpers"? I don't understand how two analog boards, each with a 16-pin output, can both connect to a single digital board with a 16-pin input.

On the first 16-pin input board you plug the J2 and J3 jumper.
On the second 16-pin input board you plug the J4 and J5 jumper.
Or you can use the 32 inputs PCB All In One too

I'm about to put together dmitri's design (2 analog x 1 digital) and I ran into the same confusion.

I don't think I understand exactly what you mean by "plug" and after reading this thread i'm a little confused as to which schematic I should be using for the analog board.

The schematic attached to this thread shows a j2-j4 on the analog connector 1. The schematic in the schematic section as of today shows a j2-j7. Which one should I go with?

Also, one more thing. I'm pretty inexperienced at reading schematics so I was hoping you could explain this.

Where the jumpers (j2-j?) are shown on the analog board I see little 1's and 2's. What exactly do they mean?

If you could maybe do up a quick connection diagram for connecting the 2 analogue boards together it would be much appreciated!

Thanks

[dmitri]

What do you mean "select with jumpers"? I don't understand how two analog boards, each with a 16-pin output, can both connect to a single digital board with a 16-pin input.

On the first 16-pin input board you plug the J2 and J3 jumper.
On the second 16-pin input board you plug the J4 and J5 jumper.
Or you can use the 32 inputs PCB All In One too

I'm about to put together dmitri's design (2 analog x 1 digital) and I ran into the same confusion.

I don't think I understand exactly what you mean by "plug" and after reading this thread i'm a little confused as to which schematic I should be using for the analog board.

The schematic attached to this thread shows a j2-j4 on the analog connector 1. The schematic in the schematic section as of today shows a j2-j7. Which one should I go with?

Doesn't matter. For 32 inputs version only j2-j5 jumpers are used. j6-j7 are reserved for future use. You just set two jumpers on j2 and j3 on the first Analogue board, and set two jumpers on j4 and j5 on the second Analogue board.

Also, one more thing. I'm pretty inexperienced at reading schematics so I was hoping you could explain this.

Where the jumpers (j2-j?) are shown on the analog board I see little 1's and 2's. What exactly do they mean?

They mean first and second pins of a jumper. You connect 1 and 2 with a jumper (like they do with jumpers on PC motherboards)

If you could maybe do up a quick connection diagram for connecting the 2 analogue boards together it would be much appreciated!

Thanks

Do not exactly understand the question. What diagram? You just connect 2 Analogue boards to a Digital with the same flat cable. Just as the do when they connect two IDE hard drives with one cable to a single IDE socket on a motherboard.