Rockit 8-Bit


While messing around on kickstarter one day, I decided to do a search on synth projects, and got a hit on Hackme’s Rockit 8-Bit kit. The bidding closed on the project in 2011, so I was curious whether it ever went forward as a finished product. With a bit of digging, I found the Hackme site, which has several open source projects. Along with the Rockit, there’s a stripped down version called the Sprockit. The designer, Matt, wrote on the site that there’s only 4 or 5 of the Rockit kits left and when they’re gone, that’s it – he’s moving on to another synth project.

The Rockit has analog oscillators, but all of the voltage controllers are digital and accessible through MIDI calls. Implying that I might be able to configure the Roland A-300 Pro to do whatever I want with it. The kit is open source, and based on the Arduino. Since I like working with the Japanino, it just keeps looking better and better. Plus, the price is about $200, including the case, and it promises to be much more flexible than the PAiA Fatman at 75% of the cost. Finally, my family was going to get it for me as a birthday present…

Building it is pretty much a breeze, compared to the Fatman. I do have some complaints, though. There’s two versions of the kit; the first version had the wrong-shaped holes for the DC power jack, and the MIDI circuit didn’t work with some devices. The second version updated the design, and resulted in some of the resistor values changing. Unfortunately, I received the older version with the wrong resistors, and had to go to the parts shop near my apartment to get the right ones. The kit was also missing 2 other resistors and the side panels for the case. Assembling the circuit board took about 6 hours, which included the time for me to go to the parts shop, and to triple-check my soldering work. I did screw up at one point, though – I wasn’t paying attention and didn’t realize that the MIDI jacks are supposed to be mounted on the bottom of the board. I had to de-solder both of those and put them in correctly. After that, I turned on power to the kit and nothing happened. No lights, nothing. After fiddling with the board and unplugging and plugging it in again, the LEDs turned on but flashed on and off REALLY slowly. I mentioned this to Matt, and he replied that he may have programmed the Arduino to use the internal clock rather than the external crystal. So now, I’m waiting for a new Arduino chip along with the missing case side panels.

The next step will be to unsolder the current Arduino, solder in the new one, and hope I don’t break anything. The kit does have a “drone” mode, which allows the oscillators to free-run independent of the microcontroller. I have to hold the front panel buttons down for several seconds for the kit to recognize them, but drone does work as-is, and it sounds pretty cool. I’m looking forward to getting the Rockit 100% functional and then plugging in the MIDI keyboard to see what I can get out of it.

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