Could I have fried the atmega?

[dmitri]

Are both Atmega32 and PIC18F2550 sitting firmly in their sockets?

[Beamtreetaker]

Yes all chips are more than firm in their sockets.

I finally got some good news again: My unit is now fully operating.
The solution for the missing USB detection was to set MIDI speed from 38400 to 31250! It now works, but if I switch it back to 38k, it won't be recognized. (Just the other way around as stated in the menu documentation! I seem to have specialized in 'other way around issues' with my megadrum e.g. the choke inversion hehe)

I just don't have a good feeling regarding stability as I did not do anything more than cleaning the pcb today. Let's hope my megadrum will work for longer than for one test drive now.....

[dmitri]

The solution for the missing USB detection was to set MIDI speed from 38400 to 31250!

Changing MIDI speed in MegaDrum menu should NOT effect USB detection in any way.

It now works, but if I switch it back to 38k, it won't be recognized. (Just the other way around as stated in the menu documentation!

No matter what speed you set, USB should still be recognized. 38k in the documentation was only meant for MIDI-over-Serial USB boards - FT232 or AVR-CDC.

I seem to have specialized in 'other way around issues' with my megadrum e.g. the choke inversion hehe)

If you're still having problems with the choke, raise it in the relevant topic.

I just don't have a good feeling regarding stability as I did not do anything more than cleaning the pcb today. Let's hope my megadrum will work for longer than for one test drive now.....

What is the exact type and make of your LCD? Isn't it drawing too much current?

In your opinion, where is the root of stability issues? Schematics? Firmware? Other?

[Beamtreetaker]

Hmm..I understand. This sounds really strange. Maybe my expectations just happened by chance, but I was able to reproduce them several times so I was really sure the midi speed was the solution here. But if it is like you said it's more likely that I am wrong here.

My display is this one: http://www.allspectrum.com/store/product_info.php?products_id=967. I will try measuring current soon maybe, but I also tested it without the display when in trouble and it still didn't work.

To your last question..I wish I could give a reasonable answer on that. I'm just trying some things out, things you propose, things that come into my mind. But I still don't know where is the root of my issues. The best explanation for all these strange things would of course be that there are bad lines/shorts on my board.

[dmitri]

Hmm..I understand. This sounds really strange. Maybe my expectations just happened by chance, but I was able to reproduce them several times so I was really sure the midi speed was the solution here. But if it is like you said it's more likely that I am wrong here.

Are you sure you don't confuse USB detection with getting actual MIDI data over USB? MegaDrum USB must be detected no matter what speed you set in MegaDrum menu, but you won't see any MIDI data if the MIDI speed set to 38K.

My display is this one: http://www.allspectrum.com/store/product_info.php?products_id=967. I will try measuring current soon maybe, but I also tested it without the display when in trouble and it still didn't work.

If you say it did not work even without the LCD, then it is not the cause of the problems, no need to measure current.

To your last question..I wish I could give a reasonable answer on that. I'm just trying some things out, things you propose, things that come into my mind. But I still don't know where is the root of my issues. The best explanation for all these strange things would of course be that there are bad lines/shorts on my board.

DIY electronics is such a thing that can sometimes cause frustration and desperation. Unfortunately? dealing with DIY is not like buying from a shelf where you can take a product back if it doesn't work. Trying to find a cause of intermittent problem with electronics, especially remotely, is a very difficult task. But believe me, if it's proven by others to work reliably it must be something to do with your particular parts/soldering/assembly.
I myself build 4 MegaDrums for developing purposes: 1 with Atmega8, 1 with Atmega32/22 inputs, 1 with Atmega32/32 inputs, 1 with dsPIC30F4011. All of them on stipboards. And with none of them I had problems you're having.
If I were in your shoes I would start from a clean sheet and build another MegaDrum just to make sure I'm not going crazy and it works just as for others or to prove something wrong with MegaDrum schematics/firmware/PCB/magnetic fields

[Beamtreetaker]

Are you sure you don't confuse USB detection with getting actual MIDI data over USB? MegaDrum USB must be detected no matter what speed you set in MegaDrum menu, but you won't see any MIDI data if the MIDI speed set to 38K.

Yes I am sure not to confuse those two aspects of USB functionality. It's still the case that 38k setting does not work (=USB device is not detected and therefore also no data is sent) but the 31k setting. Maybe I am not using the right firmware (wrong MHZ) as the ratio 38/31 is approx. the same as 20/16 and I now have shifted absolute midi speeds of 38k and 46k..? Just an assumption. (I am currently using the firmware that Synthex sent me in this thread).

DIY electronics is such a thing that can sometimes cause frustration and desperation. Unfortunately? dealing with DIY is not like buying from a shelf where you can take a product back if it doesn't work.

I was very aware of that when I decided to build the unit. Unfortunatey now exactly the situation occured that I feared, having a device that operates strangly and only a few starting points on how to debug it.

Trying to find a cause of intermittent problem with electronics, especially remotely, is a very difficult task. But believe me, if it's proven by others to work reliably it must be something to do with your particular parts/soldering/assembly.

Yeah I believe you absolutely. There must be something corrupt on my board and I just hope I will be able to find this spot. What for me makes it difficult to find is the comlexity of the whole setup, including settings, firmware, eventually faulty chips/components ...

I myself build 4 MegaDrums for developing purposes: 1 with Atmega8, 1 with Atmega32/22 inputs, 1 with Atmega32/32 inputs, 1 with dsPIC30F4011. All of them on stipboards. And with none of them I had problems you're having.
If I were in your shoes I would start from a clean sheet and build another MegaDrum just to make sure I'm not going crazy and it works just as for others or to prove something wrong with MegaDrum schematics/firmware/PCB/magnetic fields

I am thinking about that, too. I'll give my device a last chance by doing a detailed line check next weekend and resolder some of its parts. If that doesn't help I really would consider building another unit, maybe not PCB based to have more control over what I'm doing and to save some money. With a second, hopefully running, device I would have much more options to check what's the faulty part of the first one.

[Beamtreetaker]

Ouch! I found that I'm using a 12,2 Mhz crystal for the USB chip.. I didn't know that this difference would matter when buying it and I also forgot about it but yesterday after some research in the forum I read that even a slight difference in pulse won't work properly, then I checked the crystals I bought.... I will change it soon.