Appendix A: Printed circuit boards - ploopyco/mini-trackball GitHub Wiki
Buying boards from us
Getting the Ploopy Mini 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 Mini Trackball. Here's why that's great for you:
- You get a 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 Mini 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:
- 4 layers
- FR-4, TG 150-160 (basically, whatever the cheapest option is)
- 0.8mm 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
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. Use the source files to generate your manufacturing files. 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 ADNS-5050 sensors
- Digikey and Mouser carry all of the other electrical components
Here's a complete list of components:
- 1x 10118192-0001LF (USB-B Micro 2.0 Receptacle Connector 4 Position Surface Mount, Right Angle)
- 3x ACML-0805-601-T (ferrite bead, 600 ohm, 0805 1LN)
- 1x IP4220CZ6,125 (TVS diode, 5.5V, 6TSOP low capacitance, USB)
- 2x PT26-51B/TR8 (phototransistor, 940nm, right angle, 1206)
- 2x XZTHI56W-1 (infrared emitter, 880nm, 1.3V, 50mA)
- 1x EVQ-Q2B03W (tactile SPST switch, 20mA, 15V)
- 1x ADNS-5050 (optical navigation sensor)
- 1x SIDELED-A67F (amber 617nm discrete indication LED, 2V)
- 1x ECS-160-12-30B-AGM (16MHz ±25ppm crystal, 12pF, 50 Ohms, no lead)
- 1x ATMEGA32U4RC-AU (Atmel microcontroller, 44TQFP)
- 5x TS20100F070S (compact surface-mounting switch for long durability)
- 1x Atmel_ICSP (6-pin 0.100" ICSP header)
- 2x capacitor, 10uF, 25V, 0805, X5R or better
- 2x capacitor, 1uF, 25V, 0805, X5R or better
- 8x capacitor, 0.1uF, 100V, 0805, X5R or better
- 2x resistor, 10k, 1%, 0805
- 2x resistor, 1k, 1%, 0805
- 1x resistor, 100R, 1%, 0805
- 4x resistor, 22R, 1%, 0805
Step 3: Get the necessary tools
- 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 ADNS-5050 sensor and the optic. Take a look at pages 4 to 6 of the official ADNS-5050 datasheet to find out how to do this.
MAKE SURE THAT THE ADNS-5050 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.