Overview
Week 14 was a highly productive hands-on week as the project moved into the physical assembly stage. The team fired up the soldering irons to fully populate the custom PCBs, ran initial electrical power tests, and took precise physical measurements of the assembled hardware to finalize the dimensional constraints for our upcoming 3D-printed enclosure.
What We Did
- PCB Soldering & Assembly: Executed our phased assembly strategy by manually applying solder paste and soldering the surface-mount and through-hole components onto the custom 2-layer PCBs.
- Power-On Electrical Verification: Safely brought up the newly assembled boards using a benchtop power supply. We verified that the voltage regulators successfully stepped down the input power to the correct operating levels required by our microcontroller and I2C sensors.
- Physical Enclosure Measurements: With the real-world components now permanently fixed to the board, we utilized digital calipers to measure the exact vertical clearances, connector offsets, and antenna dimensions needed to update our 3D packaging files.
Key Decisions
- Component-Height Clearance Buffer: Decided to add an extra 1.5mm of vertical headroom above the highest component (the LoRa module/antenna connection) within our CAD model.
- Why: This ensures adequate internal airflow for heat dissipation and guarantees the physical casing won’t compress or strain any delicate solder joints when snapped shut.
Challenges
- Precision Surface-Mount Soldering: Soldering the tight pin pitches of the compact I2C sensors and the main microcontroller by hand required steady precision under a microscope. We had to use fine solder wick to clear a few minor solder bridges that occurred between adjacent sensor pins.
Next Steps
- Flash the unified software stack onto the newly assembled physical board and run the first on-board I2C sensor polling tests.
- Update the CAD files with our newly collected physical dimensions and print the first true-to-scale 3D enclosure.
- Conduct a basic range test with the assembled hardware to check the initial performance of the integrated LoRa antenna.