Project Logs

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• BOM Errata (read this if you ordered a PCB on Tindie)

  joey castillo • 07/16/2020 at 15:15 • 0 comments

  Yesterday a GitHub user alerted me to a typo on the printed BOM included with the E-Book FeatherWing. It was minor (omitted a part that should have been there), but if you ordered the quantities listed, you would be one part short when assembling the board. 

  This error got me worried about the Open Book BOM, so I did a check and found one typo there as well. Both errors are now fixed on the Kitspace BOM for the E-Book Wing and the Open Book, so if you haven't ordered parts yet, you can 1-click order there and be fine. But here are the two typos, so that you can work around them in your build:

  The E-Book FeatherWing

  The line for 10µF capacitors lists only one capacitor, C1. You actually need two 10µF capacitors, C1 and C2.

  C1 is a decoupling capacitor for devices on the JST ports (say, if you plan to drive a high current device like a white LED off of one of the STEMMA ports). C2 is a decoupling capacitor for the SD card. If you already ordered parts and find yourself one short, you can omit C1 and put it on C2's footprint. If you haven't ordered parts yet, order two 10µF capacitors, and populate both footprints.

  The Open Book

  The line for the 0.47Ω resistor incorrectly lists its reference as R5. That line should in fact read R12. When assembling the Open Book, you should place the 0.47Ω resistor on the R12 footprint.

  R5 is correctly listed in the previous BOM line; it's a 1KΩ resistor limiting current through the green "Battery Full" LED.

  R12 is a 0.47Ω current sense resistor for the e-paper display's boost circuit. It is required for the e-paper display to function.

  I'm really sorry about these typos, and I hope it hasn't hung anyone up in assembling their boards.

  Both the Open Book PCB and the E-Book FeatherWing PCB — with corrected documentation packets — are available on Tindie, but I am currently not shipping orders. Still, you can sign up there to be notified when shipping resumes!

• The Open Book: Final Revision

  joey castillo • 07/01/2020 at 15:46 • 0 comments

  Fifty of these arrived last month. The Open Book PCB, Revision 5: 

  I've assembled and tested one; written a system test script and a sketch to burn the bootloader using a Feather M0; completed a first draft of the documentation, and I'm almost done with the Kitspace BOM. The goal for these is to sell the bare PCB's on Tindie, for folks who want to build at home. I had hoped to have that done by the end of June, but pandemic drama has slowed me down; still, they should be available by next week. Watch the Tindie store for updates.
  

  I sense that the novel coronavirus has defined this year for most everyone; for my part, I hate to admit, it's slowed some of the progress on this project. Naturally the Take Flight with Feather stuff had to be put on hold, but the pandemic also tipped me off my axis. Back in March and April, when the pandemic was reaching its first peak, I saw folks in the maker community designing ventilators and building PPE for front line workers, and I found myself wondering how responsible it was to be ordering parts for projects that weren't actively, y'know, saving people's lives. This time also saw me wandering toward work on wearable temperature sensing as a way to build technology that could be useful in the pandemic. That was before we discovered that the most useful and life-saving technology was a piece of cloth worn over the face.
  

  Anyway. Given the constraints of the pandemic, my focus in the past month has been on making the project as DIY friendly as possible. Big friendly diagrams, a one-click BOM, detailed documentation and software tools to bring up and test in a simple, reproducible way. I wish I were posting today to say the PCB is ready to add to a shopping cart. 

  But it will be soon! 

• Live demo of the Open Book today; E-Book Wing PCB's on Tindie

  joey castillo • 05/21/2020 at 17:06 • 0 comments

  Two things! First: I've been invited to show the Open Book Project at the Open Publishing Festival at 3 PM central time today (4 PM eastern, 1 PM pacific, 8 PM GMT). It will stream live here. Check it out if you can! 

  Second: with many things on hold due to the pandemic, I had a run of the E-Book FeatherWing PCB's made for folks who want to DIY. They are now available on Tindie. 

  While it is compatible with the Open Book Arduino library, this is not the Open Book board; in addition to all the components in the BOM, you will also need a Feather M4 to serve as the brains of the operation. I chose to make this PCB available first because it is a simpler build than the Open Book, with only one fine-pitched part (the flex connector). I do plan to order a quantity of the Open Book PCB in the near future, but this is the news of today.
  

• On How To Get There From Here

  joey castillo • 01/30/2020 at 20:45 • 0 comments

  This last week has been crazy. Overwhelming, even. The Open Book was named the winner of the Take Flight with Feather contest, and I had an opportunity to demonstrate some of its functionality on the Adafruit Show and Tell. There seems to be a lot of excitement about the project! Yet I feel that something is getting lost in the conversation — and to be perfectly honest, maybe that’s on me. I’ve always envisioned this as a DIY project, an ebook you build yourself, like a Jedi building their first Lightsaber. Ever since the contest, people keep asking “when is the book coming” and there’s a part of me that feels like hey, it’s here, if you want it!

  At the same time, if I take a step back, I have to admit that actually building the book involves some knowledge and skills that may be unfamiliar or even scary to folks. I know this because a year ago, I didn’t have many of these skills. As of last May, the book looked like this: 

  The only part I soldered myself was the board atop the board on the left; it’s a few buttons and some wires. Eventually, I decided I had to design a circuit board (more learning), and eventually ended up with the E-book Wing in July:

  There’s a clear jump here. That first prototype was just through-hole buttons and wires. The wing involves a lot of surface mount stuff. And the Open Book board is an even bigger build, with more surface mount and fine-pitched parts.

  Anyway, the point is, something happened in between: I did some other, smaller projects, to gain experience with these techniques. Not going to list them all, but one milestone was the Hiking Log FeatherWing, which was a few surface mount parts: 

  Another was the Simple Feather, which was a lot of surface mount parts: 

  With each project, I was able to try these techniques on a small board that didn’t cost as much, and gain confidence and experience. Which is all by way of saying, if I’m being honest with myself, there was a time when I could not have built the Open Book, and if I’m going to say “You can build it,” maybe I need to take you along on the journey.

  So here’s the thought process: in the coming weeks, I want to document all the little projects that I’ve done over this past year. Make them into little single-serving guides, things you can build and find useful (a computerized bike light, or a GPS data logger for camping). The goal is for each one to teach some aspect of the skills needed to build the Open Book at the other end.

  We’re going to get this first run of 100 made, and I’m hopeful that there’ll be more after that, but in the end the point of this wasn’t to make a thing that you can buy, it was to make a thing that you can make. Even if you don’t think you can make it today.

• End of year State of the Book

  joey castillo • 12/30/2019 at 18:38 • 1 comment

  Some quick notes on The Open Book at end of year. First: after a lot of people asked about donations, I made a Patreon page where folks can support the work. But whatever, on to the work itself: rev 4 was a success! The new features (mic shutdown, VBUS monitor, battery full LED) work as expected, and I've updated the Arduino core and the Open Book library with support for the new pinout. I also designed a basic 3D printed enclosure and another in laser-cut wood. Both are compatible with both the Open Book board and the eBook Wing (by rotating the back piece 180 degrees).

  I've expanded the custom e-ink driver I've been writing with waveforms for quick refresh, grayscale mode and partial refresh. Improving partial refresh is a TODO item; my current waveform causes temporary ghosting after a while, and I worry it may have negative long-term effects. But I sense that if I add an invert phase to BB and WW it will improve things (at the cost of a little bit of flickering).

  Oh! I also trained a TensorFlow Lite model to recognize voice commands on the inline mic, to show my current thinking for future accessibility work. Gives good demo, even if it has trouble with the word "left". 
  

  That's accomplishments. Now, a couple of challenges:

  • I have noticed a little bit of noise on the mic input when plugged in to USB power, and I think it has to do with the way I'm connecting the USB shield to the ground plane. When I do a revision for manufacturing, I will want to add an RC filter between the USB shield and the ground plane.
  • The right-angle buttons for previous and next page feel superfluous, and they're hard to press when the board is in a case. May omit them in the future, since they're relatively pricey.
  • On a couple of boards, the Lock button fell off after a while, which tells me there's a mechanical issue there. For now I'm just applying a bunch more solder to keep the right-angle buttons secure, but I need to find some buttons with pegs to alleviate the stress of repeated pressing, or devise some other method for supporting them.
  • I'm evaluating some very tiny white right-angle LED's in the hopes of perhaps implementing a front light, though there are some challenges there.

  Thanks, everyone, for your kind words and support, and happy new year! See you in the new decade.

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