Appendix A: Printed circuit boards

Buying boards from us

Getting the Ploopy Trackball boards made can be complex, and expensive, especially if you only need one set. That's why we sell kits with everything you need to build a Ploopy Trackball. Here's why that's great for you:

• 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, so you won't have to program it
• 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 Trackball 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

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 the zip files in the source. 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.

Step 2: Order the electronics components

All of the components are described in the schematics of the PCBs. Ordering the components is left as an exercise for the reader. Here are a few tips:

• We used Alibaba to order PMW3360 sensors
• Digikey and Mouser carry all of the other electrical components

Here's a complete list of components:

• 1x 1734346-4 (USB-B 2.0 Receptacle Connector 4 Position Surface Mount, Right Angle)
• 3x ACML-0805-601-T (ferrite bead, 600 ohm, 0805 1LN)
• 1x AP2202K-3.3 (3.3V 150mA LDO regulator)
• 1x AP2204K-1.8 (1.8V 150mA LDO regulator)
• 1x ATMEGA32U4RC-AU (Atmel microcontroller, 44TQFP)
• 1x Atmel_ICSP (6-pin 0.100" ICSP header)
• 5x D2LS-21 (compact surface-mounting switch for long durability)
• 2x IP4220CZ6,125 (TVS diode, 5.5V, 6TSOP low capacitance, USB)
• 1x LFXTAL055663BULK (8MHz ±20ppm crystal, 18pF, 150 Ohms, 4-SMD, no lead)
• 1x SPMWH1228 (3V, 0.5W white LED, 2.8mm x 3.5mm)
• 2x PT26-51B/TR8 (phototransistor, 940nm, right angle, 1206)
• 2x XZTHI56W-1 (infrared emitter, 880nm, 1.3V, 50mA)
• 1x PMW3360DM-T2QU (optical gaming navigation sensor)
• 1x capacitor, 100pF, 100V, 0805, X5R or better
• 7x capacitor, 0.1uF, 100V, 0805, X5R or better
• 5x capacitor, 1uF, 25V, 0805, X5R or better
• 5x capacitor, 10uF, 25V, 0805, X5R or better
• 3x resistor, 0R, 0805
• 4x resistor, 22R, 1%, 0805
• 2x resistor, 100R, 1%, 0805
• 8x resistor, 1k, 1%, 0805
• 2x resistor, 10k, 1%, 0805

Step 3: Get the necessary tools

• Base PCB
• Vertical PCB
• All of the electronics components
• A soldering iron
• Solder
• A printout of the schematics

Schematics can be found in the source.

Step 4: Solder the components to the boards

Once you've got the PCBs and all of the components, print out the schematics. 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, and this video on using a hot-air soldering station.

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 (page 8 has visuals, for those of you who like purdy pictures).

MAKE SURE THAT THE PMW3360 IS ORIENTED CORRECTLY BEFORE YOU SOLDER IT! This is a really easy step to mess up, so DOUBLE-CHECK IT!

Step 5: All done!

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.