I blew up the LCD 16x2 output on my MegaDrum (main board with ARM STM32F205RCT6 at 120MHz). By blew up, I mean I can no longer see anything useful except full blocks of pixels on the top row and nothing on the bottom row. The unit still does trigger midi and the MegaDrum Manager FX appears to continue to work properly. BUT I am not experienced yet running Megadrum so I've not tested every function.
All components of my Full Megadrum kit worked pre the following.
Blow out happened after I extended the 16 LCD lines through a 30" DB25 cable, two DB25 connectors, and 4" to 6" of cable. I tested this, leaving power on for about 10 minutes and figured the extension worked. Then, I hooked up my 4 button keys (not from DIY Megadrum kit) and diodes on a breadboard which initially did not work. I did change the orientation of key pins thinking I may have had it backwards. Then I noticed the ground pin in the key row had no solder on it (backside) and freely slide through the board, so I added some solder. At this point I should have checked grounds for continuity but did not
Then on the 4th or 5th try (1st try after solder), the left Key worked, and I noted it worked the same as turning the right rotary. I've not been able to turn my LCD screen on (long enough) to confirm what the left button does from the initial screen. Then, I pressed the up or down key and I got this "death row of boxes".I powered off and on a few times. One or two times, MegaDrum initialized properly then returned to this "death row of boxes", sometimes a garbled set of characters appeared.
Then, I tried the rotary buttons that came with my kit.
Then, I downloaded MegadrumManager FX and connected no issue.
I updated to the latest firmware 20190602. The screen flickered but "death row of boxes" prevailed.
Then, I rolled back to firmware 20181218 and the unit initialed but within 5 minutes returned to "death row of boxes".
With a nervous twitch in between other tasks, I've tried to power it up, too many times.
I ordered a 1.8 TFT Color Display from Amazon and that would not even light up (I did jump pins 13 and 14 on LCD).
So here's what could have gone wrong:
- Incorrectly connected buttons.
- The long run of wire to LCD, when in use/keys being pressed was the failure.
- I did not shield the ends of wire where they attach to connection cups of DB25 connectors. I've google searched that image and have not found anyone to leave them bare BUT I carefully inspected all my solder joints before proceeding and everything looked good. NOTE this is my 1st real electronics project besides maintaining my own gear for 30 years.
AND Dimitri's email response was:
As far I know it is impossible to damage the main board by connecting the buttons incorrectly - I've incorrectly connected buttons (and encoders for that matter) to my test boards countless times.
The buttons pins on the main board are input pins and connected buttons cannot feed any unwanted voltage/current whichever way you connect them. On the other hand, connecting the LCD incorrectly can cause damage to the board. Btw, as far as I remember you are the first to have a problem with a kit.
I don't want to blow up another board and have to decide if I should try the extension again, in another safer way OR mount the mainboard in my controller enclosure (which I want to fit into a pocket on my chest). The enclosure in the bass drum would have drum pad, midi and maybe power connections. The midi out will go to an iTouch running Sample Tank and audio out of iTouch wireless back to my PA rack. Part of my goal with this is to go from my current set of 4 wireless transmitters (trigger kick, trigger snare, mic on crash and mic on Hi Hat) to 1 wireless transmitter for all drums.
It seems I can get a STM32 for less than $10. This board will then go into a backup position and as a working board for a 2nd backpack drum kit I intend to build.