@ Pete, if you would rotate IC2 togetter with R2 90 degrees clockwise, you could get rid of that weird angle there. Plus, if you swap RX and TX on that custom 4 pin connector, you could get rid of that one trace on solder side. Then move the connector slightly to R3 and your traces will have the room they need.
These are just suggestions, as I still believe PCB design is an art in itself 
@ Wouter
Thanks, Iāll try that out and see how things fit. Now that youāve mentioned it, I see I can really shorten some of those traces by doing that. Thanks!
I suspect if I swap +5V and ground on the pin headers on the right, Iāll be able to do some similar shortening of traces as well.
Pete
Latest, now with all 45 degree angles
At some point, I need to just call it ādone enoughā and send it in for fab. That time is likely to be Wednesday or Friday this week.
And here it is with the copper pour in place.
Very nice. One small thing, the IC1 label is on top of R3.
sorry for giving you all that extra work! But this small PCB might be the reason to get me started with Gadgeteer!
can I preorder one?
the text midi in and midi out will not be readable once assembled. You might want to repeat them on solder side
@ Wouter
Thanks. I redid the whole outline for the MIDI jacks as I didnāt care for the adafruit ones (and the SparkFun ones have bad schematic pinouts). Once I did that, I was able to fit the label in where itāll be barely visible. I didnāt want any silk screening on the back as mose fab houses charge a bunch more for that.
@ All
Ok, second issue, though: It seems like Iām stuck with vector fonts. I donāt understand why. I designed with proportional fonts, but when I look at the output from the Seeed CAM processor for Eagle, the fonts are all vector and completely screwed up. I tried with 3 different gerber viewers.
I wanted to try the ITead CAM processor (they actually do black silkscreening on prototype boards so I really wanted to use them), but their CAM processor crashes Eagle every single time. Like hard ghosted app crash. I donāt know where to start looking for issues there.
Any idea what I need to look for to get this font issue fixed? Iām pretty sure Seeed will do proportional fonts. The vector font stuff is capital U Ugly. Or do I just need to bite the bullet and do this as vector?
Pete
@ Pete
Rememberā¦these are Prototypes. Get something made, make sure it all works, then you can obsess over the right font.
Just sayinā¦ 
butā¦but, I hate vector fonts! Theyāre not even retro enough to look cool. 
(the main annoyance is that they require re-laying out all the labels, which is a pain, but itās mostly because theyāre ugly)
Pete
Submitted it to Seeed to see how it goes
Their fab is pretty inexpensive at only $10 for 10 boards of this size.
Thanks everyone for the help. Iāll post once they show up and I build and test a module.
Pete
I would hate tossing out 10 just to see if one works.
For smaller quantity (and cool purple color) I have use Temple of the Demented Diode before
http://dementeddiode.org/blog/
Good quality. Downside is waiting for a board to fill up for a run.
I sligtly remember needed to do something in eagle to get vector fonts to work right. Vectors are good, not bad. Only way to scale a font to right size you need. Maybe it was just a display thing or a switch. I canāt remember.
@ Pete I sent you an email to discuss the possibility of turning this into a production module. We love MIDI but there is no MIDI expert like Pete in this community. I have seen a picture of your lab
At $1 each, Iām not too worried. Thatās less than a soda or coffee.
Pete
@ Gus
Thanks. Replied
Pete
Ok, for the people interested in this module or a module like it, what kind of projects would you use it for, and what would your ideal API look like?
I have ideas of how Iād use it and some other ideas, but Iāll need to prioritize as well as generally fit the various approaches together
Pete
FYI: a friend just pointed out this will only work with 5v tolerant devices, which I was fine with until I realized the Hydra pins are not 5v tolerant, based on the AT91SAM9RL64 not being 5v tolerant:
Smart | Connected | Secure | Microchip Technology (section 44 of the full data sheet: http://www.atmel.com/Images/doc6289.pdf )
The STM32F4 chip used on the Cerebus seems to be a mixture of 5v and 3.3v tolerances.
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/DM00037051.pdf
I canāt really tell from that (page 99) which values come into play for the uart IO lines.
Iāve also made the assumption that the Spider is 5v tolerant. I just verified that it is by looking at the EMX manual (page 36 of this: http://www.ghielectronics.com/downloads/EMX/EMX_User_Manual.pdf )
Something to keep in mind when designing your own modules or using external devices.
Pete
By Gadgeteer specifications, your modules should never exceed 3.6V on IOs, so there is no need to dig into processor tolerances.
It took a couple reads to find that in the module builderās guide.
āThe low logic input is 0V minimum, 0.4V maximum. Logic input high is 0.7*Vdd min, Vdd+0.2 maximum.ā
With VDD presumably at 3.3v, that would give you 3.5v. +0.1v headroom gives you this:
āAll pins must be at least 3.6V tolerant.ā
Looks like Iāll need to find a way to drop that voltage to make it compliant. One possibility is seeing how well that 6n138 works at 3.3v vs 5v. Looks like Iāll have to cut a trace on one of my prototypes when they arrive
Pete
Pete
You just need to connect R2 and pin 8 of the opto to +3V3 instead of +5V and that will do it.
@ Barbadour
Right, that was my suggestion. However, Iāll need to see how well the opto runs off 3.3v. Many devices like that take a huge perf hit when you lower the voltage. Some of my other optoisolators wouldnāt work at all at 3.3v. Iāll need to test for sure
Pete