commit 816ee8a39612c549b20a527400948b268f1d9b11 parent d2c63408ba4823f32af26434cacfa22b9d030856 Author: Ed van Bruggen <edvb@uw.edu> Date: Wed, 9 Sep 2020 18:09:28 -0700 Add mechanic keyboard post Diffstat:
40 files changed, 460 insertions(+), 0 deletions(-)
diff --git a/_posts/2020-09-09-tp-mk.md b/_posts/2020-09-09-tp-mk.md @@ -0,0 +1,460 @@ +--- +title: "diy trackpoint mechanic keyboard" +tags: tech electronics mechboard thinkpad diy +categories: tech +--- + + + +I've used a mechanical keyboard for many years now. I currently own a +tenkeyless layout, even though as a programmer I almost never use the +arrow cluster or function row, so I to try the much more compact 60% +design. I also no longer care for the Cherry MX blue switches on my old board +since they are quite loud, so I went with MX clears instead in this new design. + +I have also owned many ThinkPads to use in conjunction to my desktop's +mechanical board. While ThinkPads have, in my opinion, the best laptop +keyboards, they are still nothing compared to a good mechanical keyboard. While +I could just use a regular mechanical keyboard with my laptop when needed, all +mechanical keyboard's I could find are missing an important part of the +ThinkPad's keyboard, the trackpoint. + +It because of these unique requirements that I decided to try and build my own +keyboard. I've done plenty of small electronic projects before and thought it +would be fun to attempt this new one. It also allows me to configure everything +about this keyboard the exact way I want it. + +Since I need to include a trackpoint stem in the middle of the board I also +choose to go with hand wiring a board instead of printing a custom PCB to +solder the switches onto. Since I have much more soldering experience than PCB +design I didn't think this would be too much more work and allows much more +flexibility. I sure you could somehow fit a trackpoint to a PCB it would require +much more work than I'm willing to give. + +After doing some research on what others have done in the past to install +trackpoints to their boards I found the best method is to simply savage an old +trackpoint from an existing ThinkPad keyboard. This way a lot of the hard work +and coding is already done for you, you just need to adapt it to work in your +board with your microcontroller. I found an old IBM ThinkPad's replacement +keyboard for cheap on eBay, but there are many others you can find if you get +creative and look hard enough. + +## parts + + + +* [60% plastic case][2] $15 +* [60% aluminium plate][3] $20 +* Cherry MX Switches *x61* ~$70 +* Cherry MX Keycaps *x61* ~$50 +* [MX Stabilizers][5] $7.99 +* [Through hole diodes][4] *x61* $6 +* [22 AWG Wire][6] +* [Teensy][7] 2.0 or 3.2 +* USB cable (micro or mini) +* Trackpoint module ~$15 +* 1 kΩ Resistors *x5* +* 100 kΩ Resistor *x1* +* 4.7 kΩ Resistors *x2* +* 2.2 μF Capacitor *x1* +* [30 AWG wire][10] $30 +* Shrink wrap +* [Perfboard][11] +* [Standoffs][9] *x5* +* Trackpoint stem (be creative) + +[2]: https://sentraq.com/products/plastic-60-case +[3]: https://sentraq.com/products/60-aluminum-plate-1 +[4]: https://www.amazon.com/gp/product/B06XB1R2NK +[5]: https://sentraq.com/products/cherry-stabilizers +[6]: https://www.amazon.com/dp/B01LH1FV0Y/ +[7]: https://www.amazon.com/dp/B015M3K5NG/ +[10]: https://www.amazon.com/dp/B01CK9GZV6 +[11]: https://www.amazon.com/dp/B019Q0ZTJ6 +[9]: https://www.amazon.com/dp/B07GGJ4YLC/ + +## tools + +* Hot glue gun +* Soldering iron +* Solder +* [Wire strippers][15] $21 +* Needle nose pliers +* Philips screwdriver +* Multimeter (optional) +* Alligator clips (optional) + +[15]: https://www.amazon.com/dp/B000XEUPMQ/ + +## steps + +### 1. cut aluminium plate + + + +The first modification needed to support the trackpoint is to cut the metal +plate used to hold the keycaps. This makes room for both the trackpoint's stem +and the 5 spacebar keys (2 spacebars surrounding the 3 mouse buttons). You can +see where I made the cuts in read above. You have to be careful not to cut too +much off, comprising the plates structure, while still making enough new room +for the stem to move freely and the new keys to fit straight. + + + +Shown above is the plate after the careful cuts. The right side of the spacebar +didn't turn out super straight so the far key ended up a little crooked, but +can't be noticed once the keycaps are placed. + +### 2. insert switches + +Place your choice of mechanical switches into the cut plate, I went with Cherry +MX clears. You might need to use some hot glue to hold the new spacebar keys +in place depending on how straight and tightly you cut. Because we are +hand wiring and not using a PCB to firmly attach the switches, hot glueing all +the switches could be a good idea to make it more sturdy and easier to remove +keycaps without pulling the switch out by mistake. + +It might also be wise to add the key stabilizers at this step but I forgot +this. You can add them later after everything is soldered but it is not as +easy. + + + +### 3. solder rows + +#### a) prepare diodes + + + +Cut off enough diodes from the bundle for the first row being soldered. With +this strip you can bend them all 90° at once on the anode side (side without +black or grey marking band), about a millimeter from the base. This joint is +where they are soldered onto the switches pin. By doing this at once they will +look more uniform in the finished product.It's important which side you bend +since the purpose of a diode is to act as a one way value, so if it's facing the +wrong way its not going to work. + +#### b) place solder globs + + + +To prepare soldering the diodes, place a small glob of solder on the top +left pin of each switch. I salvaged some of these switches from an old keyboard +so the image above shows some additional left over solder. + +#### c) attach diodes + + + +Use the pre placed glob to quickly solder the bent diodes down the row to all the +switches. An additional bend is then made on the cathode side near the bottom +of the switch so it can reach the next diode when they are linked in the next +step. There should still be enough overlap so you +don't have to solder the end to the bend, around 2-3 mm worked for me. +Before moving on you should use the wire cutters to trim to anode as to +clear up some space. + +#### d) link diodes + + + +Lastly connect all the diodes in each row with a bit of solder. You might have +to use some of that 22 AWG wire to extend the diodes if they don't reach +between the longer keys. + + + +Black wire extenders: + + + +#### e) repeat + +Repeat steps (a) through (d) for all the rows + + + + +### 4. solder columns + +Now that the rows are completed it's time for the columns. The 22 gauge wire is +used to connect the switch's right pins downwards. The easiest way to do this is to cut a +long wire to span the entire column with a bit left over. Simply use wire +cutters or a blade to slice the insulation at each pin and push the insulation +down before soldering. Leave enough wire at the end to attach the columns +directly to the microcontroller in the next step to reduce soldering. In +hindsight I could have left the extra wire at the top where the controller is +located but either way works. + + + +I used alternating colored wires to make connecting to the microcontroller more +organized. If you are constructing a staggered layout keyboard like me you +might not be able to connect every key to a complete column, I had two keys in +the upper left and one in the bottom right as you can see. You can get creative +with how you wire it, making a new short column like I did with the left two +switches, or attach them to existing short rows like the bottom key. You just +need to keep in mind that no two keys can be on the same row and column, +because otherwise they would appear to be the same key. + +### 5. wire the microcontroller + +With these newly soldered columns and rows it's time to connect them to the +microcontroller. First I connected the columns to the digital pins on the +Teensy board, I had to resolder a lot of new wires onto the ends since I didn't +leave enough room or couldn't bend it fully. I realized halfway through that +you didn't actually need to solder the connecting wire to the end of the +columns like you need to with the rows, so I could have simplified it. + +To connect the rows new wires are attached with different colors to make it +easy to wire and trouble shoot. + + + +### 6. attach pull up resistors + +Depending on the microcontroller you are using you might have to manually add +pull up resistors to any of the input pins. Many microcontrollers do this for +you, such as most Arduino boards. I found out the hard way that the Teensy 3.2 +does not. These resistors have to be added to each of the input rows connecting +them to ground, luckily because of the design of the matrix only 5 resistors +are needed for the 5 corresponding inputs at each of the rows. + + + +If I had know this about the Teensy before hand I would have probably come up +with a better way then just adding the resistors free standing last minute. + + + +I used shrink wrap on the long portions of exposed wire to prevent any shorts +when the keyboard is closed together. + + + +### 7. remove trackpoint + + + +The easily way to build a trackpoint into our custom keyboard is to just savage +an existing module from an old keyboard and wire it into ours. I found an old +IBM ThinkPad replacement keyboard on eBay for cheap which will work perfectly +well. There are tons of different keyboards with trackpoints that work, but the +removal, wiring, and fitting might be slightly different. + +To remove my trackpoint module form the ThinkPad keyboard I first took off the +key caps around the red dot, exposing the screws attaching it. By unscrewing +these the module should fall out. + + + +The ribbon cable connecting it can then be cut freeing the +module. Cutting it at the base of the cable where it joins with the module's +board is fine since wires will be attached directly on to the exposed solder +later. + + + +### 8. construct trackpoint circuit + +This circuit will be used to connect the pins from the trackpoint module to the +microcontroller + +#### a) resistors + +The bottom two resistors are pull-up resistors which connect the trackpoint's +clock and data lines to high so they are not left floating when there is no +data passing through them. The top resistor is used with the next step to make +an RC circuit which automatically triggers the reset pin after the appropriate +amount of time has passed, instead of having to do it in code. + + + +#### b) capacitor + +Capacitor to complete the RC circuit in order to trigger the reset pin at the +correct interval. + + + +### 9. wire trackpoint + +With the completed intermediating circuit you next need to solder the +corresponding pins on the trackpoint module to the circuit. [This GitHub +repo][25] has the pin out for various different modules so you can find the one +you salvaged. Since the exposed pins on the module are normally very close +together it is necessary to use the very thin 30 AWG wire here. I also +recommend using some electrical type to make sure none of the wires come loose. + +[25]: https://github.com/alonswartz/trackpoint/tree/master/pinouts + + + +### 10. test trackpoint + +In order to test to make sure the trackpoint works correctly solder more +wire (any will do) to the other side of the RC circuit and use a breadboard or alligator +clips to test the trackpoint, circuit, and wiring with the teensy. + + + +### 11. flash firmware + +To confirm that the keyboard is working correctly so far we need to connect the +teensy to a computer and upload firmware to read all the inputs and communicate +with your device. There are many different tutorials online about uploading +code to our microcontroller, I used [the official teensy arduino tutorial][32] +so that I could push code with the easy-to-use arduino IDE. + +[32]: https://www.pjrc.com/teensy/tutorial.html + +Once you know how to upload code we now need the actual code that's going to +make the keyboard work. Depending on the choice of microcontroller, the well +supported [QMK firmware][33] is a good choice. Unfortunately I realized too +late that the teensy 3.2's new ARM processor was not supported when I +originally tried QMK, so I had to write my own arduino code from scratch +which can be found [here][34]. Either way since this is a custom hand wired +board you will need to tweak the program to the layout you wired + +[33]: https://qmk.fm/ +[34]: https://gist.github.com/edvb/2b63ac6ac29eeb5bb1cdd117f2b5b5ed + + + +### 12. attach trackpoint + +Once the teensy is working with the trackpoint it can be soldered permanently +to the board. + + + +The trackpoint module was then hot glued to the bottom of the case. Depending +on the case the thin protruding support structures might need to be clipped off +in order to fit the module as low as possible. + + + +I chose to position the module sideways since placing it straight down would +require me to cut out much more of the case's supporting structure. This just +meant that I needed to tweak the code a bit so that the new orientation is +taken into account. + +### 13. construct trackpoint stem + +To control the trackpoint from outside the keyboard enclosure a stem +needs to be attach to the top of the module. This is the point where you have +to get pretty creative as there are many different ways to achieve this. Some +people use a lip piercing, one of the keys themselves, or a simple screw. +Since I had some screws and bolts laying around I opted for this option as it +seemed the simplest. + + + +To make the screw feel more like a traditional trackpoint some coarse sandpaper +cut with a hole puncher was glued to the top of the screw and red spray paint +was coated on the top of it. While the sandpaper gives the screw texture, +the paint covering it gives it a softer and rubbery feel which is much less +harsh then the sandpaper by itself. + + + +### 14. attach trackpoint stem + + + +To attach the screw to the trackpoint the textured red control was removed and +a series of washers and a bolt were first super glued together and then glued +onto the controller of the module. This allows a short screw to be easily +attach and detached from the board controlling the direction the cursor +moves. + + + +A small amount of silicone tape is added to the end of the threads of the screw +to reduce the amount of play in the screw, making its movements more precise. + + + +A new wire has to be connected as well to make the stem fit through the +previously cut opening. + +### 15. attach standoffs + +Since the trackpoint requires extra room in the case the top plate needs to be +raised above from where it normally sits so the keys aren't interfering with +the trackpoint. This can be done in many different ways, but I decided to go +with motherboard standoffs that fit over the existing screw bases. + + + + + +### 16. keycaps + +#### a) trim keycaps + +To make room for the trackpoint stem outside of the cause and allow it to +freely move the edges might have to be trimmed out of the surrounding keycaps. +I did this by simply pressing hard on the corner with a sharp blade, but +similar results could be achieved with a dremel, drill, or file. For me only +the G and H keys needed to be modified, but depending on the trackpoint's +position the top of the B key might also need to be filed down. + + + +#### b) place keycaps + + + +The rest of the keycaps can now be placed according to the layout below. + + + +More silicone type might be required to get the keycaps with stabilizers to fit +correctly. + + + + + + +## future + +[![https://xkcd\.com/243/][1]](https://xkcd.com/243/) + +[1]: https://imgs.xkcd.com/comics/appropriate_term.png "I know a lot of people hate these, but I prefer them to touchpads." + +In future projects I probably won't choose to use a teensy 3.0 again unless +there is significant shift away from the currently popular 2.3 non-ARM +architecture supported by most firmwares. + +I also need a micro USB port to attach to the case so the cable can be removed +and reattached from outside, currently there is just a hole leading to +the microcontroller directly. + +If I were doing it over I would also think more careful about where I position +the microcontroller and wires since right now the USB port on the board is +facing away from the case's opening making the cable be a little tangled +inside. + +Overall I am extremely happy with how the keyboard turned out and learned a lot +from making it myself. Feel free to [contact](/contact) me with any questions +or advice with your own keyboard! + +## see also + +Here are some other useful guides which I used: + +* [A different hand wiring build log][26] +* [Another hand wiring log][27] +* [Keyboard matrix tutorial][28] +* [QMK's hand wiring guide][29] +* [Trackpoint keyboard build][30] +* [Trackpoint keyboard tutorial][31] + +[26]: https://deskthority.net/workshop-f7/brownfox-step-by-step-t6050.html +[27]: http://www.davecooper.org/i-built-a-keyboard +[28]: http://www.dribin.org/dave/keyboard/one_html/ +[29]: https://github.com/qmk/qmk_firmware/blob/master/docs/hand_wire.md +[30]: https://imgur.com/a/O6BdH +[31]: https://github.com/alonswartz/trackpoint diff --git a/assets/img/posts/tp-mk/columns.jpg b/assets/img/posts/tp-mk/columns.jpg Binary files differ. diff --git a/assets/img/posts/tp-mk/cut-keycaps.jpg b/assets/img/posts/tp-mk/cut-keycaps.jpg Binary files differ. diff --git a/assets/img/posts/tp-mk/diodes-done.jpg 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