LCD+grounding problem

[orsku]

I was testing my Megadrum a while ago and immediately faced a problem. When I hook up the USB-cable, the MIDI-led blinks once but the LCD shows nothing sensible. Here's a crappy mobile phone picture taken in a way too dark room:
http://www.freewebs.com/purgatory2/24102008269.jpg
Sorry for the size too.

It's an old LCD so my guess is that it's broken. What do you think?

[dmitri]

It does look like broken.

[orsku]

I bought a new LCD display today and it works fine. Thanks for the help.

[orsku]

This time my problems aren't concerning the LCD but I'll post it in this thread anyway.

I finished my Megadrum and started testing it with my pads and I'm having some major problems. I'm pretty sure it has something to do with grounding this time. However, I have no idea how to fix it so here we go:

When I hook up nothing but the USB cable everything seems to be fine. When I connect any pad, I start getting endless MIDI activity (according to the LED) even though none of the VU-meters dance unless I hit the pad. The same problem appears if I use external power adapter and a MIDI-cable.

Megadrum seems to work fine on itself but the problems start when I connect it to my computer.

The endless MIDI activity stops every now and then for a while if I touch the metal enclosure of my PC.

This is how I did the grounding of the jacks: There's some aluminium tape on the back panel to connect each jack's body, and only one jack is connected to the PCB with a wire. I have tested with a multimeter that the jacks really are all grounded. Is this OK?

There's 6 GND pins in the 40pin connector but I only used one of them to ground all the jacks. Is this OK? The others are left empty.


One part of the problem is that I don't see any activity in MIDIOX input monitor even though I should, but maybe we'll solve the grounding problem first.

Thank you.

[orsku]

Okay. I've been trying to solve my problem, and made some progress. I got rid of the noise problem when using external power and MIDI. However, I still get no MIDI activity in MIDI-OX. The problem isn't with my PC, because it works with my MIDI keyboard.

I would really appreciate your help.

[Synthex]

There's 6 GND pins in the 40pin connector but I only used one of them to ground all the jacks. Is this OK? The others are left empty.

It's better to use more than one connector to ground all the jacks.
Don't take your module in your hand to test it.

[orsku]

I found a ridicilous mistake I had made. Majority of the jacks I'm using don't have switches, but 3 of them does. I had connected the ground wire to one of these 3, and accidentally soldered it to the "pin" of the switch, not the sleeve of the jack (I don't know the right word for the pin).

Anyway, now my MIDI out works fine. Still having a weird problem with the USB, though. When I connect the USB cable, Megadrum works fine for a while, but after about 30 seconds it suddenly stops sending any MIDI data. Reboot doesn't help, but after some time it works again.

Luckily I don't need the USB now, but ofcourse it's a little disturbing to know that it doesn't work.

Tomorrow I will update the new firmware which supports Yamaha 3-zone cymbals. Then I just need to configure it to work well with my pads and I think I'll be done. I'll post some pics and maybe a video clip when it's ready. Thank you for making this possible.

Oh yeah, and the LCD backlight is very dim, so I'll replace the 470 resistor with a smaller one.

[dmitri]

Anyway, now my MIDI out works fine. Still having a weird problem with the USB, though. When I connect the USB cable, Megadrum works fine for a while, but after about 30 seconds it suddenly stops sending any MIDI data. Reboot doesn't help, but after some time it works again.

Sounds like a loose connection between Atmega and PIC18F2550 or PIC18F2550 not sitting properly in its socket.

[orsku]

Now I'm having some new problems and getting really frustrated.

I updated the new firmware with PonyProg2000. It wrote and verified OK, and the Megadrum seems to be working as it should be (according to the LCD) with the new firmware. It doesn't though.

First of all, the USB doesn't work at all anymore. Windows doesn't recognize Megadrum anymore. This is the smallest of my problems.

The main problem is that after the update Megadrum doesn't even send appropriate MIDI data out. It somehow reacts to hitting the pads but that's about all of the good news. It doesn't pick even nearly all of the hits, and the velocity of the MIDI-note it send doesn't correspond very well with the velocity of the hit. The velocity of the note changes dramatically even if I try to keep my hits the same.

MIDI-OX's input monitor looks just like one would assume. Nothing sensible.

What went wrong?

I bought Synthex's kit which included Atmega32 16PU, and I wrote the "megadrum32_16_32_20081020" version of the new firmware. It is the right one, isn't it?

I couldn't find the previous firmware so I wasn't able to test if it would work.

Sorry to bother you again, but I can't solve this one by myself. Any help will be highly appreciated.

[Synthex]

I bought Synthex's kit which included Atmega32 16PU, and I wrote the "megadrum32_16_32_20081020" version of the new firmware. It is the right one, isn't it?

The Atmega32 was already programmed with the firmware AND the bootloader.
Why did not you use the bootloader with MIDI-OX ?

If you use a 20 MHz crystal, you must use the "megadrum32_20_32_20081020" version of the new firmware.