Good news and bad news --
Good news: It worked!
Bad news: I'm not going to be selling off this run of boards.
Why: I made three oversights in designing this board.
The biggest one was the omission of a resistor necessary for the bootloader to actually load on boot. The board can be modded to make space for the resistor because the ground-plane is right next to the pin. Easy fix, but hacky.
The other two oversights are regarding both buttons. (1) The spec for the mode switch rotated the landing pad orientation 90 degrees from the reference drawing (wut?). The result - the button is facing the wrong direction, but works. (2) I used a pre-made library part for the Teensy's reset button, but both the landing pad and orientation was wrong (wut?). My fault for not double checking. The result - the button is rotated wrong, and doesn't work. There are fixes for both these, but also hacky.
The plan: I'm going to make a revision for some new boards to come next month to give it another go.
Lessons learned:
- When shopping for SMD components, make sure you're not accidentally ordering metric profile codes. There's a huge difference between 0402 imperial and 0402 metric.
- 0402 components are a bitch to solder by hand. Don't do that to yourself. 0603 is still very small and much more reasonable to solder.
- Always, always, always check to see if pin 1 is where is should be before soldering everything in place.
- Invest in a soldering station if you're remotely serious about things. I'm loving my new Hakko 888 (10/10 would recommend).
Other thoughts:
The plan was to keep from modding the case. And, while it cleared the plastic case, the metal sheath for the cartridge protruded into the board and needed to be clipped to fit. Not something I wanted to do. Incidentally, with the pin-headers acting as stand-offs for the shield, I was able to clear the processor entirely -- so I actually had a lot more room to work with than I had previously imagined. The negative side of this is that the USB was really high in the socket, making it difficult to plug-in the cable. The solution is to find a connector that will affix to the side of the board, not the top. This (I think) would put it at an ideal height, but would require scrapping the current design to make space for the inset part-profile. I probably was going to need to do that anyway to make space for the 0603 parts replacing the 0402 ones.
xray303 wrote:Nice Project. About the integrated teensy, did you get a special deal with PJRC (creator of teeny) as the teensy is based on the HalfKay bootloader which is closed source and as i know you cannot download it to install the bootloader on your own microcontroller.
The PJRC store sells pre-flashed ATmega32U4 in a QFP profile for easier hand-soldering. I didn't know it was there until someone on those forums pointed it out to me.
And, you're right, it is closed source. The Arduino Leonardo has MIDI support, but I haven't gotten to tinkering with it yet. Might be a preferable alternative if it works.
And, for those who don't know, Noiseinabox (xray303) is responsible for the Teensyboy's existence. Thanks, btw.
Last edited by bit 9 (Dec 28, 2015 6:34 pm)