3.1 Synthex board problem (1 row of solid white boxes)

[samdrum]

That would explain the undesired behavior, because then the input pins are directly connected to ground. I will check it out. Thanks ignotus!

[samdrum]

Problems with the buttons are solved after some rewiring! Thanks gentlemen.

The other "issue", with the first VU meter staying up, is actually desired behaviour, as documented here:

https://www.megadrum.info/~megadrum/forums/viewtopic.php?p=7417#p7417

MIDI LED activity and the top left VU meter activity is probably due to not having HH pedal connected and having 'AutoLevels' for the HH pedal set to Yes (which is default). In this case smallest signal level change on the HH input will be generating MIDI CC messages. You can either connect a HH pedal or change 'AutoLevels' for the HH pedal to No and adjust 'LowLevel' and 'HighLevel' until MIDI activity from the HH pedal stops.

Now everything seems to work, apart from the USB issues I'm experiencing (USB connection goes on and off at unpredictable moments). I will investigate this further (also in the forum) and revert to a separate thread since this one is becoming offtopic.

Thanks for your generous help everybody!

[Firelord]

USB connection goes on and off at unpredictable moments

Please expand on that.

One known issue (so far reported in connection with Dmitri's design only, as far as I know) is that MD loses the USB connection because of power noise. I.e. when you turn a high-power device on or off near the computer with MegaDrum plugged in via USB.

[samdrum]

I've been reading the post on power noise but I'm not sure if that's the issue, because the on/off usb sound happens quite often (couple of times per minute), so not only when I switch another power device on/off.

Board type: Synthex 2.8
Firmware: 20090517 (supplied by Synthex)
Chip: ATMega32 16PU 0807D
Used crystal: 16Mhz (as advised for this Chip in the build instructions by Synthex).

So what happens is that the device quickly switches off and on (I can hear the usb on/off sound in windows quickly after each other). At first I thought that it was a loose connection, but even when I don't touch the device this happens.

Furthermore, I checked the USB cable and it is ok. I've used another USB cable and experienced the same symptoms. I also tried to put the cable in a different port & usb controller. Same results.

Any first thoughts of what the problem could be? Thanks!

ps. Maybe good to mention that I'm reluctant to update the firmware via USB at this point, because I'm not sure what would happen if during an update the usb connection fails.

[ignotus]

So what happens is that the device quickly switches off and on (I can hear the usb on/off sound in windows quickly after each other). At first I thought that it was a loose connection, but even when I don't touch the device this happens.

You might need the pullup resistor described in the topic called "Possible issue with some PIC18F2550 samples and a fix" (Hardware section; sticky). My MD started blinking on and off on my computer and this resistor solved the issue. Have a look, it might be that.

[Firelord]

So what happens is that the device quickly switches off and on (I can hear the usb on/off sound in windows quickly after each other). At first I thought that it was a loose connection, but even when I don't touch the device this happens.

Ok, this is not the power noise issue.

Did you wash the flux off the board after soldering? If flux is left on the board it can cause strange behaviour sometimes. And, as mentioned above, you could take a look at this topic.

[dmitri]

And, as mentioned above, you could take a look at this topic.

If Synthexe's kits come with PIC18F14K50 programmed with my version of the USB firmware, than the above mentioned topic is irrelevant.

[samdrum]

If Synthexe's kits come with PIC18F14K50 programmed with my version of the USB firmware, than the above mentioned topic is irrelevant.

Does that apply for both the PIC18F14K50 firmware update AND the pullup resistor fix? That is, in case I have the right firmware (don't know how I can check this yet), would the pullup resistor improve the situation?

I cleaned the board using isopropyl alcohol and unfortunately it doesn't help.

Also, while I don't know if this is of any importance, when booting with MIDI speed 38400, the computer doesn't detect Megadrum as a usb audio device, though it is adviced in the manual to use this MIDI speed for usb.

Any suggestions where to start? Thanks.

[dmitri]

If Synthexe's kits come with PIC18F14K50 programmed with my version of the USB firmware, than the above mentioned topic is irrelevant.

Does that apply for both the PIC18F14K50 firmware update AND the pullup resistor fix?That is, in case I have the right firmware (don't know how I can check this yet), would the pullup resistor improve the situation?

Synthex's kit v3.1 already has the pullup resistor - R28. You should ask Synthex about the firmware in the PIC.

I cleaned the board using isopropyl alcohol and unfortunately it doesn't help.

Also, while I don't know if this is of any importance, when booting with MIDI speed 38400, the computer doesn't detect Megadrum as a usb audio device, though it is adviced in the manual to use this MIDI speed for usb.

Where in the manual is it advised? I will correct it.

[Firelord]

If Synthexe's kits come with PIC18F14K50 programmed with my version of the USB firmware, than the above mentioned topic is irrelevant.

I'll keep that in mind.