Idea

Looking at the mini-PCIe specs, the connector has mandatory USB 2.0 lines so communication was solved. The area available, roughly 5.1 x 3.0 cm, is not too bad  -more than how big the Arduino Nano is in comparison. The biggest challenge probably was that there are only 3.3V power lines available, and most example designs use 5V power supply.

Fortunately Arduino is released under quite permissive Creative Commons CC-BY-SA license, which means whoever makes an Arduino clone, also has to release it under the same license. This gave a lot of interesting designs to scout and learn from.

The original plan was using a similar Bill of Materials as the Nano, based around the ATmega328P, but two things happened to change it. First, I’ve changed my mind that I didn’t want to use the FTDI FT232 chip they used for USB-to-UART conversion. Second, my clever electronics friend Niko figured out that the tiny bit more advanced ATmega32U4 microcontroller would also work at 3.3V and since it speaks USB natively, could cut a bunch of components (that’s always good). The trade-off is a bit of clock speed (running at 8MHz), but that’s acceptable.

Design

I did find clone with these parameters (3.3V power and ATmega32U4), the SparkFun Pro Micro 3.3V.  Took that basic design, replaced some components, added a Power LED,  and broke out the pins differently. Done in KiCad, the result is this PCIeDuino design below (or check the PDF version).

The next step was fitting all these components onto a mini-PCIe card. The board size was sketched in detail in the specs, though somehow all the dimensions were described in a way that it was quite inconvenient for making a board outline. Nothing that an hour of math cannot fix…

Actually, had to do the board layout twice, because for the first prototype (that I actually got printed) somehow had a crystal footprint that doesn’t correspond to any available 8Mhz crystal that I needed – so had to start again a bit. I took that chance to reorganize the board bit, and that extra round of design did a lot of good to the quality! More logical layout, better component grouping, simplified arrangement.

The biggest challenge at this stage was wiring the output pins. That part was done with a few tries of autorouting with FreeRouting. The idea being that it’s a low frequency, small board so likely not too demanding design-wise, and getting it printed is more important that fine-tuning it to death. The USB line was hand-matched, though, and the LEDs were arranged to face the same way for easier mounting, so not all just auto-optimize.

The tape-out happened in May, about 9 months after getting started (and about 4 months downtime in between). The resulting board looks like this:

I’ve submitted the board to Seeed Studio’s Fusion PCB service, and got it back in about 2 weeks. In the meantime the components were ordered from Mouser, the parts for 10 boards (equal to the number of PCBs printed)  just being above the minimum threshold for free shipping.

Alive

Then came the assembly – hand soldered surface mount components can be really frustrating, but I really got to like them by now. If only my left hand was better (I’m right handed – solder in right hand, tweezers supposed to be in left). The assembly took about 1 hour altogether.

Now it’s time for waking the board up. Fortunately SparkFun’s Pro Micro firmware fits nicely onto the PCIeDuino too. Using an USBTinyISP clone (from eBay), a bunch of pogo pins, and the ISP headers on the board I could flash the firmware.

Plug it into the the embedded board and powering up, the blinking D13 LED showed that everything should be pretty close to alright!

Since then I’ve assembled altogether 7 of the boards (still takes about 1 hour each by hand, but I’m getting better). Had a few failures, but now I also know how to diagnose those issues better.

(If curious, so far had “magic smoke”, cold joint, shorted microcontroller pins, and now a board with a short somewhere that triggered the fuse. Ah, the learning!)

Advanced

Now the PCIeDuino is available on Tindie (whenever I have a bit of time to assemble more). It a great experience trying to make a compelling maker project that other people want to use too! Having better documentation, more explanation, better software, better communication, and actually going out finding people who are interested in this could be pretty much full time work!

I got my first Hackaday feature too, not that it was a great article, but the discussion was very illuminating and helped me to polish my own idea regarding this project.

All the KiCAd source and Gerber files are available on Github with CC-BY-SA license, so others can take this design to places too!

Future

The PCIeDuino is still very much a prototype project, more suitable probably for advanced users who are not put off when not every path is well worn out. I have to test it a lot more too, and find interesting use cases!

It looks like that the SparkFun firmware is not very well maintained, and it could be useful to look for alternatives. Optiboot seems to be interesting, but it also needs some work for the ATmega32U4 chip. Software support is super important, though, so this got to be a high priority improvement.

The original idea was to use this on embedded boards, that are mostly ARM systems. It should also be easy to use, Arduino IDE compatible project. The problem is, that the two parts are at odds with each other. The Arduino IDE doesn’t quite work well on ARM yet, so it’s mostly command line operation at the moment. Not a breaking change, but still a fail that needs to be remedied somehow.

The board is designed to conform to the mini-PCIe board specs. It fulfills the full-sized board variation’s requirements: the board outline, 1.0mm PCB thickness, connector pins,  mounting, keep out zones, …. It does not do the beveled cut at the connector (45º bevel cut needed, but seems to work regardless). To help other people to design mini-PCIe boards, I’ve put together a bare board starter kit in KiCad, available on Github, which includes the connector schematic, board outline, pin placement, and top-end mounting holes. Would be good to make a half-sized board variation design as well in the future, though at the moment it’s not a priority (pull requests welcome!)

This project also gave me a lot of ideas for future devices: similar mini-PCIe designs with ATXmega or ARM Cortex-M microcontrollers, and other Arduino clones with special functionality, e.g. built around the ATmega2564RF2 for  802.15.4 mesh networking… But first, take this design to its full potential…

If you like this idea, check out the PCIeDuino on Tindie, and would love to hear any kind of feedback or comment too! There’s a lot to improve, even if this is really the most complex electronics design I made so far… Now back to the drawing board and to soldering!

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There were 8 speakers scheduled from different companies and background: RS Components, Via, Broadcom, Motoduino, TMI Holding…. and me from Taipei Hackerspace. First I was wondering how do I fit in there, and maybe my talk *was* out of place a bit. Most talks were in Chinese so I could grasp only basic stuff from them, although the slides helped – most people made slides following the “slides are my notes” style, which is not my style, but was welcome this time. It was also great to see seasoned speakers like Richard from Via, and Lucas from TMI giving fun (and informative!) talks.

I did feel I’m in the right company, though. Open Source Hardware is becoming more and more of my focus – or maybe I’m just realizing it now that what I do is called such. Part of the audience were industry professionals and part enthusiastic hobbyists & students, and I had some great chat in the breaks with both kind of people.

I heard about the National Science Fair here (what? I got to check that out!), and how much interesting work people do with interactive hardware and elementary/high school kids. There is waaaay more going on that I can imagine, and there’s a lot more potential to tap into.

Had a chance to gather some industry experience too. Naren from Broadcom, who was responsible for getting Raspberry Pi into production was telling the story how they were expecting only 10,000 orders altogether and got 350,000 on the first day (sold 1.8 million to date), so they had to scramble an entire new supply chain. Thought that came to me was that maybe that’s one of the biggest value of  Kickstarter/Indiegogo is to be able to get an order of magnitude estimate of the demand.

Also heard about Via’s experience in pursuing new design and materials with their APC platform (such as using paper for housing), and interacting with their community. Heard a lot from RS Components how they are building tools for their community, and building the community itself. The demo was fought with technical difficulties (first rule of presenting is not to assume a working/fast internet connection), but it was inspiring nonetheless, and gave me some big (and difficult) ideas for my project: have to see if there’s any good community for scientific/laboratory electronics and hardware building, and if there isn’t then build one.

One of my favorite part in these events though to meet friends’ friends. This time was no exception, even if there was too little time to talk, I left with quite a few people in mind who I will need to contact soon, because they are doing something awesome and connected to my area of interest, either in hardware or in startups. This is one reason I’m trying to be really generous with my time and making introductions between people who I recon would hit it off well: I was the recepient of that so many times that I got to give back too.

My talk

I was scheduled in the middle of the afternoon just before tea break, and I was one of two people who used English for their talk (out of the 8 speakers). I was more nervous

I’ve uploaded the slides used for the talk in advance as well, so now it’s all out in the open.

My favorite part writing this talk was probably the attempt to summarize the philosophy and values of the maker movement, in a way that would inspire others. Some bits:

• Don’t accept crappy – everything can be changed and improved upon.
• Aim for collaborative creation. Celebrate the weird. Don’t mock.
• Do and then share the results for everyone to learn from it.
• For things to happen, you have to show up. Don’t wait for someone else to start, build up and inner motivation
• Everyone’s values are different, a ‘space is often a different canvas for everyone.

So far the feedback I got about the talk is that I should have mentioned the projects people were working on in the ‘space, and upcoming events. That would have made a better ending for sure, and I had an extra 5 minutes or so to do that. Definitely going to emphasize the practical aspect next time.

Another thing I noticed listening to (a bit of) the video is that I need to use much less “ehm” and “ahm”… I certainly don’t remember using any, and consciously trying to avoid it in my talks in the recent years, I guess I need to listen more carefully (and prepare better).

Any more suggestions? What else wasn’t good? Bring it on, I want to become better at this.

More about the Taipei Hackerspace is on the mailing list, which is open for everyone to sign up, ask questions, show their projects, and hear more about what’s up.

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About two weeks ago, I have fixed a headphone for a friend: the wire near the jack was broken and needed replacement. It was a relatively straightforward project, but needed a bit of digging into audio wires and jack connections. I was really proud of the result (fixing things have this effect, I highly recommend doing more of that!), and kept thinking if I can come up with any other audio-related project where I can use the knowledge I learned, and this is what I have came up with:

I bring my laptop almost everywhere with me, and started to use my smartphone headset to listen to music since it sounds great and much lighter to bring with me than the large headphones. It also has a built in microphone, so if I can use that, then really don’t need any other equipment to make Skype/Google+ Hangout calls. Those are 4-conductor headphones for Left/Right/Ground/Microphone channels, but computers (PCs) can only use the 3-conductor Left/Right/Ground and Mic/Mic/Ground connectors. Let’s make an adapter so I can break out the audio lines and mic lines to the appropriate laptop connectors!

Hardware setup

The parts needed:

• 1pc 4-conductor input socket
• 2pc 3-conductor output jack
• 1pc 1-signal (mono) audio wire (signal + ground lines), about 15cm per finished adapter
• 1pc 2-signal (stereo) audio wire (2 signals + ground), same length

The Guanghua Computer Market and its neighbourhood has a lot of electronics stores. The appropriate output 3-conductor jacks were really easy to find, as were the audio cables. Those didn’t look as good as the Bose headphone that I repaired, but it’s good for a prototype. The hardest part was the 4-conductor input socket: they had some that should be mounted on a printed circuit board, and tried that one for the first prototype, but then they found me some better one that I can use with the cables. That was the most expensive part at about 20TWD ($0.70).

Above is the circuit schematic, probably a bit of a mess, but tried to keep it simple. Then aim of the whole setup is to get the G (ground) + M (mic) lines to one jack (the mono audio, thinner cable), and G + L (left) + R (right) to another (stereo audio, ticker cable).

One complication is that the order of M-G-R-L seems to be the “Apple Way”, that my HTC headphone adopted as well, while others have a more logical (and easier to solder) G-M-R-L series (eg. the Sony PSP headphones as I found searching for it). Thus this adapter would not work for every headphone. Maybe version 3 should have a switch to swap the Mic and Ground lines at the input socket?

After all the parts are collected, there’s some micro-surgery. Strip the audio wires carefully, and don’t have to leave much out, just enough to get to the jack electrodes, and such that the thick outside cover fits into the cramp that is there to hold things in place.

For the microphone wire, connect the two output channels (the tip and the 2nd ring), and the ground goes to the base one. For the audio output, the tip is the left channel, the 2nd ring is the right, and the base is ground. The audio wire I got was a bit thick to cramp, but it’s not too bad if the metal cuts into the plastic cover, as long as it doesn’t cut through it.

The input socket was quite a bit trickier to solder, because the electrodes were so tiny. They are arranged in a 4 directions, going around clockwise as “tip – 2nd ring – 3rd ring – base”. Had to use some magnifying glass and one spare unsoldered jack to make sure I connect the right things to the right places, but it works – mostly. The hardest part is not to melt the individual wire insulation (they are not enameled wired as inside the manufactured headphones). Also, cramping the two wire together is tougher, had to cut off the sleeve of the socket so the wires fit within the plastic cover of the socket.

This second version was done within about 15-20 minutes, though, since I had all most of the research done previously. Had to do some careful inspection that no shorts developed within the device because of the soldering, and then connect everything up.

The listening sound quality is pretty good, though I guess it could be improved with better soldering (which includes using a finer tip soldering iron), and more patient cabling work. The mic is pretty nice, my recordings sound much better than before, and it’s convenient to use too. Much less thing to carry around and definitely better than my laptop’s built in mic. This might even get me to make more calls (sorry Mum and Dad that I haven’t been phoning too much lately!)

Taking it further

The electronic markets here in Taiwan are full of gadgets, and I looked but couldn’t really see any commercial adapter that did the same thing. This made me think that maybe it could be interesting to make this into an actual product. First find some local factories that could make it, as I keep hearing my business-related friends manufacturing a lot of things. Then set up a Kickstarter/Indiegogo project with some reasonable (let’s call it hobby-level) financial goal, and see whether people would be interested.

This would need quite a bit of preparation, and what’s putting me off is the simplicity of the project (what’s too simple for Kickstarter?), and that a Chinese factory could rip it off faster then you can say Shenzhen. Still, it might worth it for the experience and contacts, will do some research, and in the meantime keep making stuff that interests me.

Update 8/6: as a commenter pointed out, these things exists already e.g. on Amazon, searching for “smartphone headset pc adapter”. I guess that simplifies the future a bit, have more time for better projects.

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