My future megadrum (another one that will give it a try)

[elrules]

Hello dmitri, I have been following your progress with your DIY module. It is great! I have now decided to register the forum because I'm going to build my own one. I have just purchases an LCD screen from ebay, and will buy the rest of components from Farnell.

I have some doubts:

1) when ordering components, I can see that in the list you don't include connectors. How are called those you use for connecting analog and digital board with a floppy disk cable?

2) if you build all the circuit in one board I suppose you can forget about conectors (the ones shown in each page of the PDF schematics to join each part), can`t you?

3) how is going to be physically the 32 input version of megadrum? using two twin analog boards? If i build the boards separatedly, as in you pictures, will I be able to update my circuit with only few changes to convert it to the 32 inputs version? Do you recommend me to wait some days for the 32 inptus schematics?

4) I am very curious of how some of you make a PCB design. Is there any tool to build PCB designs? How much does it cost? Is it very difficult to use it? I have the right amount of knowledge to solder small circuits, but I don`t know if PCB is difficult or not for me (and expensive)...

5) How is the latency now? someone said megadrum was quicker triggering than the roland td-12, but other said it was slow. Who's right? The latency issue is due to the atmega or due to the USB interface. I have an Edirol UM-1ex (usb-midi interface) so what option is better/quicker triggering: using true USB interface, or using MIDI out with the edirol interface?

Well, that`s all I`ll keep posting here if finally I start building it.

Thanks to all

[dmitri]

Hello dmitri, I have been following your progress with your DIY module. It is great! I have now decided to register the forum because I'm going to build my own one. I have just purchases an LCD screen from ebay, and will buy the rest of components from Farnell.

I have some doubts:

1) when ordering components, I can see that in the list you don't include connectors. How are called those you use for connecting analog and digital board with a floppy disk cable?

Example of a 16 way socket: http://uk.farnell.com/jsp/Connectors/I/ ... ku=1099238
Example of a 16 way header plug: http://uk.farnell.com/jsp/Connectors/PC ... ku=8395934

2) if you build all the circuit in one board I suppose you can forget about conectors (the ones shown in each page of the PDF schematics to join each part), can`t you?

You will still have to connect an LCD, Keyboard, Programming cable somehow.

3) how is going to be physically the 32 input version of megadrum? using two twin analog boards? If i build the boards separatedly, as in you pictures, will I be able to update my circuit with only few changes to convert it to the 32 inputs version? Do you recommend me to wait some days for the 32 inptus schematics?

I recommend building all boards separately: 1) easier to make. 2) easier to find problems. 3) it will allow easier upgrade to 32/40/48/56/64...256 inputs versions.
It's up to you if you want to wait or not. It may happen you'll have to wait for months or it may become available tomorrow:)

4) I am very curious of how some of you make a PCB design. Is there any tool to build PCB designs? How much does it cost? Is it very difficult to use it? I have the right amount of knowledge to solder small circuits, but I don`t know if PCB is difficult or not for me (and expensive)...

I used free version of DipTrace to design PCBs. To some it may appear difficult to use, to others - a piece of cake. Making PCBs at home is a matter of right amount of knowledge, determination, equipment, drill&drill bits and it still may turn out it's better to have them ordered.

5) How is the latency now? someone said megadrum was quicker triggering than the roland td-12, but other said it was slow.

I'm curious who said it was slow?

Who's right? The latency issue is due to the atmega or due to the USB interface. I have an Edirol UM-1ex (usb-midi interface) so what option is better/quicker triggering: using true USB interface, or using MIDI out with the edirol interface?

Some latency is unavoidable since signals from pads have to be sampled and measured. MegaDrum itself has under 4ms latency. Standard MIDI out doesn't introduce any additional latency. I guess same thing with Synthex's USB MIDI. Don't know exaclty how to measure latency for AVR-CDC or FT232 USB boards.

Well, that`s all I`ll keep posting here if finally I start building it.

Thanks to all

Good luck!

[elrules]

Thanks for your answers.

I have seen two different kind of boards on this forum.

The one you used, that has rows of holes connected. An the one from another user, which has all the holes disconnected and he used thin lines of tin to connect the components.

Could you post links from Farnell to both types of boards? What measures did you use? What kind of board do you think that makes easier the mounting?

To cut the rows of holes to avoid connectivity (I mean that holes you made underneath the atmega) what tool do you use?

And... if a buy an atmega32-20mhz, will the 20mhz overclock firmware work with that atmega? I want to buy directly an atmega32 that works at 20mhz, so to avoid doing overclock. Any advise on that?

Thanks again

[dmitri]

Thanks for your answers.

I have seen two different kind of boards on this forum.

The one you used, that has rows of holes connected. An the one from another user, which has all the holes disconnected and he used thin lines of tin to connect the components.

Could you post links from Farnell to both types of boards? What measures did you use? What kind of board do you think that makes easier the mounting?

Stripboard: http://uk.farnell.com/jsp/Semiconductor ... ku=1172154
Matrix board: http://uk.farnell.com/jsp/Semiconductor ... ku=1172182
For me personally stripboard is easier since it requires less wires.

To cut the rows of holes to avoid connectivity (I mean that holes you made underneath the atmega) what tool do you use?

http://uk.farnell.com/jsp/Mechanical,+O ... ku=3360568

And... if a buy an atmega32-20mhz, will the 20mhz overclock firmware work with that atmega? I want to buy directly an atmega32 that works at 20mhz, so to avoid doing overclock. Any advise on that?

Officially 16MHz is a maximum for Atmega32. To run at 20MHz without overclocking you will need Atmega324 and another firmware (which I can compile if you want).

[elrules]

Hi, I am building my order to farnell, and I am sure missing a lot of things.

Can you tell me a link to?:

- Female midi conector
- Linear ic socket (like this one but male version)
- Nice buttons

Is this socket valid for the atmega?

Is this conector valid for stripboard gap between holes?

[dmitri]

If nobody answers these questions sooner I'll try to answer them tonight. I'm just a bit busy at the moment.

[dmitri]

Hi, I am building my order to farnell, and I am sure missing a lot of things.

Can you tell me a link to?:

- Female midi conector

I think any DIN 5 180DEG will be fine, e.g.:
http://es.farnell.com/jsp/Connectors/Au ... ku=1204611
http://es.farnell.com/jsp/Connectors/Au ... ku=1193819

- Linear ic socket (like this one but male version)

This will do: http://es.farnell.com/jsp/Connectors/IC ... ku=1101347
(key word is DIL, e.g. DIL 40, DIL 16)

- Nice buttons

Sorry, you'll have to choose it yourself, it's a matter of taste:)

Is this socket valid for the atmega?

It is.

Is this conector valid for stripboard gap between holes?

What do you want to use it for? I don't see it fit anywhere on MegaDrum boards.

[elrules]

- Linear ic socket (like this one but male version)

This will do: http://es.farnell.com/jsp/Connectors/IC ... ku=1101347
(key word is DIL, e.g. DIL 40, DIL 16)

It is not what I am looking for. What I mean is an array with "male" pins on both sides, that you have in your digital board (pictures on the web) to connect the parallel cable coming from the analog board. You also use them to connect the cable coming from the LCD.

Is this conector valid for stripboard gap between holes?

What do you want to use it for? I don't see it fit anywhere on MegaDrum boards.

I thought that this could be a good option to connect digital and analog boards, instead of using two-rows connectors. Will they fit with the connectors on the board and with a common parallel cable? And if not, then I would use this and this
Is there any item number in farnell for the IDE cable you use to connect boards and LCD? Is it easy to sold/connect the IDE cable to the IDE connector?

PD: sorry if I ask too much, but the farnell catalog is huge and I get lost in it.

[dmitri]

- Linear ic socket (like this one but male version)

This will do: http://es.farnell.com/jsp/Connectors/IC ... ku=1101347
(key word is DIL, e.g. DIL 40, DIL 16)

It is not what I am looking for. What I mean is an array with "male" pins on both sides, that you have in your digital board (pictures on the web) to connect the parallel cable coming from the analog board. You also use them to connect the cable coming from the LCD.

Then I guess this is what you are looking for:
http://uk.farnell.com/jsp/Connectors/PC ... ku=8395934

Is this conector valid for stripboard gap between holes?

What do you want to use it for? I don't see it fit anywhere on MegaDrum boards.

I thought that this could be a good option to connect digital and analog boards, instead of using two-rows connectors. Will they fit with the connectors on the board and with a common parallel cable? And if not, then I would use this and this
Is there any item number in farnell for the IDE cable you use to connect boards and LCD? Is it easy to sold/connect the IDE cable to the IDE connector?

You can use an old IDE cable. They're probably called ribbon cables but I didn't buy it at Farnell. You don't solder it, you clip it - look at IDE or floppy disk cables.

[elrules]

Then I guess this is what you are looking for:
http://uk.farnell.com/jsp/Connectors/PC ... ku=8395934

Hmmmmmm more or less. But that has a plastic enclosure and the pins are in all together in two rows. What I meant was: pins in only one row, without plastic enclosure. Only a row of male pins, long enough so you can cut the number of pins you need. (you have a lot of them in your digital board on the photos of the website)