www.megadrum.info

I have built megadrum using the Synthex v2.8 kit. How can I test it to make sure I've done built it properly and it's working?

I've downloaded the MCT and selected the Megadrum as the MIDI input device and MIDI output device (i.e. it was recogized).
I am currently in the process of building DIY drums so I connected a piezo to pins 1 (Ground) and 5 (Kick) of the 32 input cable (IDE Cable) for testing purposes using alligator clips.
I am not using an LCD yet (waiting on a connector to be shipped).
I'm using USB (not MIDI connectors & power).

What should happen when I tap the piezo? I expected to see the PCB LED light, the pad hit velocity bar to register a hit in MCT and also for the MIDI log to record a hit. None of these events occurs. Is there something additional I need to do in MCT for this basic test? Is there something I need to do with the megadrum buttons to start or initialize?

Thurston wrote:What should happen when I tap the piezo? I expected to see the PCB LED light, the pad hit velocity bar to register a hit in MCT and also for the MIDI log to record a hit. None of these events occurs.

If the PCB LED light does not light, there is a problem with the Atmega.
Is the LED flash when you switch on the Megadrum ?

Do not touch any buttons just yet, your kit came with Atmega pre-programmed. If you press wrong buttons at the wrong time you could erase MegaDrum firmware before you made sure Atmega<->PIC18F communication is working properly.

When you touch with tweezers or something metallic one of the pins 37-40 your MIDI LED should light up (provided you connected it correctly) and MCT should register MIDI activity (provided Atmega's firmware and crystal's frequency match, I guess it should be 16MHz in your case).

If you don't see MIDI LED activity, check for short circuits, breaks. Check that you have +5 on power pins of Atmega (10 and 30).

I have made an embarrasing mistake. After looking at the picture posted by avara here: viewtopic.php?f=3&t=456&start=80 I discovered that I had installed the Atmega installed upside-down. I have removed and reinstalled in the proper orientation. I am going to go over the rest of the board and check for any other mistakes including shorts and breaks before I waste any more of your time. To answer your questions, (with the Atmega installed properly) :

Synthex wrote: Is the LED flash when you switch on the Megadrum ?

Do you mean does the LED flash when I connect the USB cable? If so the answer is no, it does not flash.

dmitri wrote:When you touch with tweezers or something metallic one of the pins 37-40 your MIDI LED should light up (provided you connected it correctly) and MCT should register MIDI activity (provided Atmega's firmware and crystal's frequency match, I guess it should be 16MHz in your case).

If you don't see MIDI LED activity, check for short circuits, breaks. Check that you have +5 on power pins of Atmega (10 and 30).

Contact between pin 37 and pin 40 = still no flash (16MHz crystal installed)
I am getting +5 on Atmega pins 10 & 30.

1. Make sure that you have unbroken connection between pin 15 of Atmega and pin 18 of PIC18F2550.
2. With Atmega out of the socket, make sure you don't have shorts between each pin of Atmega - pins 1 and 2, 1-3, 1- 4,...,1-40, 2-3, 2-4,..., 2-40,...,38-39,38-40,39-40.
3. Make sure none of Atmega pins have shorts to the ground or to +5, except pins 11,31(gnd) and 10,30(+5).

I doubled checked all the components and they appear to be properly installed. There are no shorts or breaks.

dmitri wrote:1. Make sure that you have unbroken connection between pin 15 of Atmega and pin 18 of PIC18F2550.
2. With Atmega out of the socket, make sure you don't have shorts between each pin of Atmega - pins 1 and 2, 1-3, 1- 4,...,1-40, 2-3, 2-4,..., 2-40,...,38-39,38-40,39-40.
3. Make sure none of Atmega pins have shorts to the ground or to +5, except pins 11,31(gnd) and 10,30(+5).

1. Connection confirmed (zero resistance between pins)
2. Confirmed no shorts between pin 1 and all other pins, between pn 2 and all other pins, between 38 & 39, 38 & 40, and between 39 & 40.
3. Confirmed only pins 11 & 31 are grounded (to USB pin 4) and only pins 10 & 30 are connected to +5 (USB pin 1)

Thanks for the suggestions. Do you think the Atmega programming could have been disturbed by installing it upside down?

Thurston wrote:Do you think the Atmega programming could have been disturbed by installing it upside down?

It is a possibility ...

With the LCD, it would be easier to debug.

Thurston wrote:2. Confirmed no shorts between pin 1 and all other pins, between pn 2 and all other pins, between 38 & 39, 38 & 40, and between 39 & 40.

You did check 3-4, 3-5,...,3-40,4-5,...,4-40,... and so on, didn't you?

Try one more thing. Turn it on. Start measuring voltage on pin 3 of the LCD connector.
Press the key UP and keep it pressed for a few seconds. Was the voltage on the pin 3 of the LCD connector changing?
Press the key DOWN and keep it pressed for a few seconds. Was the voltage on the pin 3 of the LCD connector changing?

dmitri wrote:You did check 3-4, 3-5,...,3-40,4-5,...,4-40,... and so on, didn't you?

No I didn't ...but now that I understand I have checked every pin against all others. Between pins 11 and 31 I get a reading of 1.4 Ohms. Between 10 and 30 I get 442 Ohms. All other readings were much higher (1000+).

dmitri wrote:Try one more thing. Turn it on. Start measuring voltage on pin 3 of the LCD connector.
Press the key UP and keep it pressed for a few seconds. Was the voltage on the pin 3 of the LCD connector changing??

Yes, the voltage went down.

dmitri wrote:Press the key DOWN and keep it pressed for a few seconds. Was the voltage on the pin 3 of the LCD connector changing?

Yes, the voltage went up.