Created Appendix A: Printed circuit boards (markdown)

Appendix-A:-Printed-circuit-boards.md

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+# Buying boards from us
+Getting the Ploopy Mouse boards made can be complex, and expensive, especially if you only need one set. That's why we sell sets of Ploopy Mouse boards **TODO put link to ploopy.co store here**. Here's why that's great for you:
+
+**TODO PIX a base PCB and a vertical PCB laid out side by side, fully soldered but not yet assembled**
+
+- You get a base PCB with all components soldered
+- You get a vertical PCB with all components soldered
+- The firmware is already programmed on the microcontroller
+- It'll cost a hell of a lot less than if you do a production run of PCBs just for yourself
+- You won't have to order components and wait while they come in
+- We guarantee that it works
+
+Just something to consider. You're smart. You'll figure it out.
+
+# Making your own boards
+Want to make your own Ploopy Mouse boards? Great! Less work for us. Seriously, though, only choose this option if you know what you're doing. You don't want to embarrass yourself, do you?
+
+## Step 1: Order the PCBs from a PCB production company
+
+We use PCBWay for our boards. You may use them **TODO add PCBWay published PCB link here**, or any other PCB production company. Here are the most important configurations you'll need to communicate to the company:
+
+*Main board*
+- 4 layers
+- FR-4, TG 150-160 (basically, whatever the cheapest option is)
+- 1.6mm thickness
+- 6/6mil track/spacing distance
+- 0.3mm minimum hole size
+- ENIG surface finish, but you can go with HASL if you don't care about lead poisoning
+- 1oz copper thickness for both outer and inner layers
+- Choose whatever colours you want for solder mask and silkscreen; we like white solder mask and black silkscreen
+
+*Vertical board*
+- 2 layers
+- Everything else is the same as for the main board
+
+If something is missing from here, it's not really important.
+
+At some point, you'll have to upload design files to the production company. Send them `/hardware/electricals/production/gerbers.zip` **TODO add this**. That should contain everything you need to get the boards made. If the production company rejects this package, however, you'll need to address the issue yourself.
+
+We estimate that it'll probably cost around $80 to get the boards made, plus shipping.
+
+## Step 2: Order the electronics components
+
+All of the components are described in the schematics of the PCBs (see `/hardware/electricals/production/base.pdf` and `/hardware/electricals/production/vertical.pdf` **TODO ADD THESE**). Ordering the components is left as an exercise for the reader. Here are a few tips:
+
+- We used Alibaba to order PMW3360 sensors
+- Digikey carries all of the other electrical components
+
+Here's a complete list of components:
+
+**TODO add entire BOM here with descriptors**
+
+## Step 3: Get the necessary tools
+**TODO PIX all tools necessary**
+- Base PCB
+- Vertical PCB
+- All components
+- A soldering iron
+- Solder
+- All components
+- A printout of the schematics
+
+Schematics can be found in `/hardware/electricals/production/base.pdf` and `/hardware/electricals/production/vertical.pdf`.
+
+## Step 4: Solder the components to the boards
+
+Once you've got the PCBs and all of the components, print out the schematics (see `/hardware/electricals/production/base.pdf` and `/hardware/electricals/production/vertical.pdf` **TODO ADD THESE**). Use the schematics to match the reference designators on the PCBs to the reference designators on the schematics, and then get to soldering.
+
+If you've never soldered surface mount components before, or want a refresher on how to solder, we recommend [this video on using an iron to solder surface mount components](https://www.youtube.com/watch?v=3NN7UGWYmBY), and [this video on using a hot-air soldering station](https://www.youtube.com/watch?v=c_Qt5CtUlqY).
+
+Lastly, you'll need to follow a set of special instructions to assemble the PMW3360 sensor and the optic. [Take a look at page 11 of the official PMW3360 datasheet to find out how to do this](https://d3s5r33r268y59.cloudfront.net/datasheets/9604/2017-05-07-18-19-11/PMS0058-PMW3360DM-T2QU-DS-R1.50-26092016._20161202173741.pdf) (page 8 has visuals, for those of you who like purdy pictures).
+
+## Step 5: All done!
+**TODO PIX a base PCB and a vertical PCB laid out side by side, fully soldered but not yet assembled**
+Congrats, you finished assembling the electronics! Pat yourself on the back.
+
+You'll need to program the microcontroller before it works. Head over to `Appendix C: Firmware Programming` to get at it.