Ordering OpenString PCBs requires having a PCB fabrication house produce the boards from the provided design files, and sourcing the components for assembly. Below are guidelines and recommendations for both steps.
A complete set of fabrication files is provided at hardware/fabrication/gerbers/: Gerber files for all copper, soldermask, and silkscreen layers, edge cuts, drill files (PTH and NPTH), and a .gbrjob manifest. Most fab houses accept the folder as a zipped upload.
If you'd rather skip fabrication and assembly, Cryosphere Innovation can supply ready-to-use OpenString boards. Email cjp@cryosphereinnovation.com for pricing and lead time.
Fabrication Considerations
40 cm length
The OpenString PCB is 40 cm × 1.6 cm. That length sits at or beyond the maximum board dimension for most fabs' standard instant-quote tiers, so you may need to request a manual quote instead. Below you'll find two suppliers that have successfully produced OpenString PCBs: MacroFab and PCBWay. If ordering from another vendor, you'll want to confirm that they can accommodate the extended length.
Castellated edges
The PCB has castellated through-holes at both ends so boards can be soldered end-to-end into a continuous string. This is a feature you'll likely need to request explicitly. Most fabs support it but treat it as an extra-cost option.
Recommended fab houses
- MacroFab — US-based, full turnkey manufacturing and assembly. Best if you want a single vendor handling boards, parts sourcing, and pick-and-place.
- PCBWay — China-based, fast and inexpensive for bare boards, with optional assembly service. Good default for prototype runs.
2. Bill of materials
The canonical BOM used for PCBA is hardware/fabrication/bom.xlsx. There is only one line item: the DS28EA00 temperature sensor. Each OpenString PCB requires 20 DS28EA00s, which are spaced at 2 cm intervals along the board.
DS28EA00 chips are a cousin of the ubiquitous DS18B20, but with an extra GPIO that allows them to discover their position on a bus. This enables OpenString to read chips in a known order, enabling sequential temperature detection.
Most parts are available from Digi-Key, Mouser, Newark, or any other authorized vendor.
Other components
- Soldering equipment and basic electronic hand tools
- Hook up wire
- A computer with the Arduino IDE (and/or PlatformIO) installed
- Sealing / potting supplies appropriate to your deployment
Recommended:
- An Arduino Uno or similar microcontroller for testing and development. In this example, we use an Adafruit Feather M0