Topic: Making

RFID Reader v2 Starts

2018-06-07 23:14 - Making

The first working prototype of the next version of my RFID reader project.

I've used Arduinos for some time now, for electronics projects. They're very easy to get started with, but a little bit limited. As I called out in the VFD clock project I did a few years ago, STM32 is a nice next step up. Pictured is a Maple Mini clone I still had from that project, easily available for around $5. Even better is the (as it's colloquially known) "Blue Pill board with almost the same functionality at around $2, and it's close cousin the "Black Pill". More speed and RAM and Flash, more peripherals. More exciting!

I designed a multi-headed RFID reader project, on top of an Arduino core. After some delays it's finally seen real usage, and revealed several opportunities for improvement. Mostly around the hardware, but if I'm going to redesign, I want to take the opportunity to revisit the software as well.

On my clock project, I found the SDK very detail-heavy and hard to work with. ST Microelectronics, which makes the STM32 chips, also makes a package called STM32CubeMX, a code generator that makes the SDK easier to consume. But it wants to output projects that specifically work with a small handful of professional (read: $$$) IDE packages. I recently discovered that Atollic TrueSTUDIO, which is in that list, is available for free download! I've spent a fair deal of free time, in small chunks, recently getting these all set up and working, and especially understood.

The plan is to take advantage of FreeRTOS, which the Cube tool can include with just a click, to handle scheduling and some other things to make this next version both faster and more stable. For now at least, I've got a proof of concept, working end-to-end, able to read cards and developed with a capable IDE with breakpoints and value inspection built right in.

Custom Game Case, from Unused Koozie

2018-05-29 17:12 - Making

The pair of source Koozies, with the Game Boy Micro on top. Top sewn up, bottom cut open, sides sewn. Flipped right side out. Tucked in. Flap closed.

Several months ago I got a pair of Koozies, which have sat unused since then. More recently I've pulled out my Game Boy Micro, which has no protective case, unlike most of my portable devices. I realized that the Koozie was the right sort of material, soft and padded, and almost exactly the right size. So I cut one side of the bottom off, sewed closed the top, and sewed the sides in closer, to be the right size. After flipping it right side out and confirming a good fit, I trimmed what was the bottom of the Koozie down, to be a flap which I can tuck in to cover the open side. It worked out quite nicely!

The wi-so-serial works!

2018-03-24 21:33 - Making

The first working wi-so-serial, installed.

For months, stalled by a partially broken computer, I've been working on this project. I have a server at home (and another for remote backups, at a relative's house). And I've got full disk encryption which needs a password to unlock, at boot. Which means if it ever reboots I have to physically be there to get it going again. I'd like to be able to administer my servers remotely.

I've looked into commercial IP KVM devices, but they cost hundreds of dollars. Since I'm working with Linux here, in theory all I need is a serial terminal. So I've designed a serial-to-WiFi bridge. The picture above is the first one that I've ever had working, installed. The ribbon cable hooks up to the internal serial port header, the green terminal plugs into an unused USB port header for power. Then there's snaking trails of several other pairs of wires: one each hooking to the case and to the motherboard for the power LED, the power button, and the reset button.

Most newer motherboards power their USB ports all the time, even while the computer is off, this one included. So I can remotely power up or down, restart, and then control the computer. In theory. I've just gotten far enough to test all this, and discover performance issues. I've got all the computer-side setup to manage, yet. But after working on this since August, it's great to have it finally proven to really be workable.

Hokkaido Milk Bread

2018-02-20 14:31 - Making

I recentely learned about the tangzhong bread making method. I pickeda recipe and decided to try it.

The dough is formed. Dough has risen, is divided and rolled and set in (the wrong) pan. Baked!

So I made the dough first of course. Then, I didn't know where my Mom kept her bread loaf pans so I used a Bundt pan instead. And I don't know where the pastry brush is, so I didn't do the egg wash. But it still came out quite nice. Very dense, and certainly tasty. Worth trying again with a few more details "right".

Custom Garbage Bag Holder

2017-12-25 20:24 - Making

The bag holder, "in place" except lifted up a bit for demo purposes.

Just in time* for Xmas, I put together this custom garbage bag holder for my Mom. Following availability at local grocery stores she's switched to plastic bags, and been awkwardly using them on this built in garbage bin, where they're too small to fit properly. Here's a mostly plywood contraption to fit over the existing bin, but with pegs to hold the bags' handles plus some cove molding to help keep the bag open and in place. It's about the same depth but narrower than the bin beneath it to be the right size for standard plastic shopping bags. A cutout in the lower layer of plywood fits around the lip of the bin, while the top layer holds all the bits mentioned above. It's all made from found materials already around the house, which is the perfect kind of gift for my Mom. No new/extra stuff!

* I definitely had an idea to do this over the Thanksgiving visit. And earlier in this visit. And forgot, despite a coded (to not give away the surprise) note to myself. Then I thought of it again, and realized what the note meant, and built this up over (mostly) a long afternoon on Xmas Eve.

KQ Button Tester; nee Turbo Button

2017-11-16 22:19 - Making

My KQ Turbo Button device, on a messy desk.

I've never posted here about this device I made. I made it earlier this year, mostly as a joke. On the right, now mostly hidden by the fan, is a solenoid. It sits poised above a yellow arcade button, also mostly hidden by the fan. On the front of this view is the electronics and the controls are on the top, all glued to a huge 12 volt lead acid battery.

The original point was to be able to press that button with inhuman speed and accuracy. I managed to leverage that to contribute to some of my videos about Killer Queen. More recently I've been interested in figuring out how to pick good arcade hardware. The moving parts wear out and need replacing. Which ones to buy as replacements?

So I updated the device, not only can it push the button — normally the one in the real arcade, now (in the extra little bit of wood it's sitting on) a dedicated one — it can read its value. So it can be used to derive fine details about the performance of the button, when pressed. I want to do quite a bit with this. Here's one example:

ED 0
D 12272
U 12280
D 12284
U 12540
D 12832
U 12836
D 12844
EU 0
U 8364

That starts ED 0 for "event down zero". Then a bunch of lines D and U indicate the timing of "down" and "up" events observed, in microseconds since we started the "down" event. All real mechanical switches "bounce" a bit when activated (and deactivated, usually). In this case, the button first went down about 12 milliseconds after we started (it takes some time for the solenoid coil to charge up, then to physically move) and the switch contacts bounced apart and back together three times after that, taking just over half a millisecond to settle down into its final resting state. And in this case when it came back up, there were no bounces. In my limited experience so far, this looks like good performance for such switches.

This is just one bit of data but we can compare quality in the "bounciness" category pretty easily: how many bounces, and how long before the last one is done? I intend to follow this with a post containing a detailed summary of this, for several switches. I need to make a final call on exactly what I want to measure, and make sure my tool will do that if at all possible, so it will take a little time.

PCB Prototyping Service Review: JLCPCB

2017-10-01 10:46 - Making

Scan of a board produced by JLCPCB.

Disclaimer: the PCBs pictured and discussed in this article were provided to me at no cost, in return for writing this review. I've received no other compensation and this is my own personal un-altered opinion.

Recently I was contacted about a new PCB prototyping service called JLCPCB and asked to do a review. I've done a few of these over time, and this is much the same. Pictured at left is four copies, two front and two back, of the board that I had made for this review.

It's a simple board so I can't comment on high density pads, but all of the traces, holes, and solder mask appear to be well aligned. The silkscreen is solid and legible everywhere. Overall, I would say these are perfectly fine boards.

I got ten copies, and they were all generally fine. Look (very) closely at the far bottom right of the image, though. You'll have to go full resolution to see it, but there's some scuffing around the pads near the bottom middle and bottom right. Cosmetic only, it seems, and the other nine boards had no issues or only even more minor scuffs/scrapes.


JLCPCB's claim to fame appears to be their $2 minimum cost. This applies only to the first board in any given order, and shipping from China applies to any order. So really you can get a few copies of one board made for $2, but you can only get it delivered for more like $12. Add a second board to the same order (e.g. to share the shipping overhead) and it will be $5.

Customer Numbers

Just like EasyEDA, this is some sort of batching service, which adds customer numbers in the silkscreen. They do say this ahead of time, but as I've called out in earlier reviews, I really don't like it. Especially here. I explicitly put in the in the "remark" box that I'd prefer this number to be located under U2 or U1. It would fit in either place. But instead, it was put out near the edge in the most visible place.

Final Call

These are fine boards, there's (almost) nothing wrong with them. But if I'm going to pay a couple bucks for the boards, plus $10 to $15 for shipping, I'd rather go with Elecrow's "special" service, ten copies up to 10x10cm for $5 — with no extra customer number printed.

Quarto Game Board

2017-08-11 12:57 - Making

I recently discovered (via the awesomely named YouTube channel I Like To Make Stuff) of a board game called Quarto. It's got simple rules and it's pretty easy to make a set yourself. I'm visiting my Mom in New Jersey, and that means access to some tools I couldn't keep in the city.

Rounding the material for half the pieces. The pieces are all rough cut out.
The board is a grid routed into some already-finished wood. Complete!

I picked some already-one-inch-square scrap available, it seems to be PVC. I rounded off the corners on the router table, then cut out eight short pieces and eight tall pieces, half of each from the rounded over section and half from some raw square section. Then half of the pieces got holes drilled in the top, and half got spray painted black.

The board is another scrap piece, of wood that was already finished. A grid of shallow lines, again with the router table, formed the play spaces. I chamfered the edges and with the paint dry, it was done!

This was a quick and dirty project. The grid lines were not routed the best, and the spray paint leaves a lot to be desired. But they're definitely good enough to play with. So I'll give that a try, and then decide if it's worth trying again, with perhaps better materials and more care.

Killer Queen Berry Flower Plush

2017-07-29 12:04 - Making

An in-game berry flower, full of berries. An in-game berry flower, picked clean. I've hardly posted about it, besides the tapper buttons I made last year, but since early 2016 I've been spending a lot of time playing an arcade game called Killer Queen. It's played by ten people at once, in two teams of five. The social aspect of working with your team to outplay the other one turns a fantastic game into an addictive one. At left and right here are two pictures of one of the key parts of the game: these yellow flowers are scattered around the play area. They start, like at left, full of six berries and often end up like at right, plucked clean. The berries are central to play, being a direct path to one of the win conditions and also the means by which players upgrade themselves to pursue the others.

One of the very dedicated players that I know thanks to this game is pregnant, with her baby due in just a few weeks. A coworker and fellow player had the wonderful idea to give a Killer Queen themed baby gift, and one was a plush berry flower toy. I was excited from the moment I heard the idea. I finished making it, and gifted it, this week. Here's a photo gallery plus some explanation of the build process.

Some fuzzy pom-poms will be the berries. A plush berry pile, on a flower-to-be.

First was gathering materials. There's some yellow felt here for the flower, and some fuzzy pom-poms of just the right color to stand in for the berries. I had to make two orders of these. At first I just got six, because that's how many there are in game. Once I saw them in person though, I realized I'd need to make a pyramid in three dimensions for this to make sense as a physical object.

The first of the petals, top and bottom, being stitched together. Using printed paper templates, I cut four petals out of yellow felt, and sewed two layers together.

I found what seemed like a reasonable petal shape and drew it out on the computer, then printed it out on paper for templates. These were traced onto yellow felt which was sewed and trimmed into the final outer shape. It took two tries to get the size right. This worked out great: though I wanted the profile of the smaller size, using the larger size ended up being just the right amount of extra material to wrap around the depth I wanted. So I sewed and cut the outer shape of all four petals. Each was one sheet of felt, cut in half and stitched together into a pocket.

An early step of sewing the separate petals into one flower, two seams join one petal to either side of a third.. Continuing the process of flower assembly, all four petals are either sewn together already, or pinned in place for sewing. The first half of flower assembly complete:  All four petals are sewn together on one side.  The other side

With all four separate petals prepared, the next step was to start sewing them together into one flower. This involved pinning the remaining flaps in place, stitching from the outer corner of two petals down to the middle, and repeating three more times. When done one side of the flower was sewed up, with flaps remaining on the other side.

A piece of upholstery foam is cut into the flower shape. The foam is stuffed into the flower, by flipping it inside out over the foam. After fit was confirmed, a few last seams were done by machine, leaving the smallest flap open for stuffing the foam through while inverting the felt flower around it.

The plan is to flip the felt flower inside out around a piece of upholstery foam, leaving it stuffed and plush, with the seams hidden inside. This was tested first, and the fit was fine. So the foam came back out and two of the four remaining seams were done by machine, again on what would be the inside. With a smaller open hole left, the flower was stuffed again, leaving just a few loose flaps.

Stitching the second of the remaining seams by hand, from the outside. Last seams of the flower complete, foam stuffed inside.

The remaining two seams were stitched by hand. This leaves a raised seam, but they'll be hidden shortly.

A green pistil and some berries are laid out to plan their placement. The pistil is stitched in place.

I had hardly noticed despite playing the game for over a year, until I looked closely for this project: There's a green structure that holds the berries. I'm choosing to call this the pistil (a discrete organ in the center of a flower capable of receiving pollen and producing a fruit). So I made a simple cone out of green felt and stuffed with a bit more foam, with the intent that it holds up the higher layers of berries without crushing the lower ones. I laid the bottom layer of berries in an arrangement that would mostly cover the raised seams, and leave room for the pistil in the middle. Then stitched the pistil in place, again by hand.

The petal The lower layer of berries were stitched onto the petals. The lower layer of berries are all in place.

Next I added the vein pattern onto the top of the flowers. I found a reasonable image online, then traced out the main structure and stretched and tweaked it to fit my exact petal shape. I printed this out onto paper and cut out the shape to form a stencil, which was drawn over with a marker. With that done, the first layer of berries were stitched onto the petals in a triangle shape, around the pistil.

Two more layers of berries are stitched onto the pistil, to form a tetrahedral shape. The finished flower, shot one. The finished flower, shot two.

All that remained was to attach the final four berries. These went onto the pistil, using its structure to help with the shape. Which did not end up perfect. There was more slack than I hoped for, but I'm still very happy with the final result!