Two boards are part of the Tempo project: Tempo and Peakick. Both explore modern sensor ICs for use in skydiving. The Peakick board is more research oriented. Peakick is design as a daughter board for a experimentation with a range of microcontroller boards. It is most easily connected to SparkFun "Thing Plus" form factor boards, although it can be connected to almost any modern MCU/SOC board supporting 3.3V peripherals.
Tempo is a purpose built single board logger derived from Peakick. It adds a SAMD51 MCU onto a Peakick board. This project includes PlatformIO-based firmware to drive this board as a stand-alone skidiving data logger.
This project was originally designed to experiment with real-time audible feedback at assist a skydiver in freefall. The original Peakick design stacks a SparkFun ESP32 Thing Plus atop a custom GNSS/sensor combo board. The SparkFun board supports an audio connection to Bluetooth earbuds or headphones.
- GPS/GNSS using a u-blox SAM-M10Q
- 6-DOF Inertial measurement / gyro using a ICM-42688-V
- Barometric pressure / temperature using a BPM390
- 3-DOF Compass/Magnetic measurement using a MMC5983MA
I am just getting started with this project, so all I'm doing for now is velidating the sensor board designs and (soon) experimenting with basic BT audio capabilities.
| Folder | Description |
|---|---|
| hardware | KiCad PCB projects (using KiCad 7) |
| hardware/peakick | (original) u-blox GNSS + IMU + Barometric sensor PCB |
| hardware/tempo | (newer design) SAMD51 + u-blox GNSS + IMU + Barometric sensor PCB |
| enclosure | 3D-printable enclosure (Fusion360 format) |
| firmware | Arduino sketches |
| platformio | Platformio test and operational projects for Tempo board |
| platformio/tempo-logger | Skydiving logger firmware for the Tempo board |
The enclosures are designed to be SLA printable. I print using a MakerBot Replicator 2 with Cura 5.3.1 as the slicer. Print resolution set to 0.15mm.
The PCBs are secured to the enclosure using M2.5 brass inserts and screws. The inserts are heat-inserted into the bottom shell using a soldering iron after printing.
Both boards were created using KiCad 7.0. In peakick, in order to get the header alignment with the parent board as acccurate as possible, I imported the SparkFun STM32 Thing Plus GitHub project to use its PCB layout.
I prefer 1 oz. Copper with ENIG finish. I ordered the V1 PCB from OSHPark and stencils from OSH as well.
| QTY | MPN | Description |
|---|---|---|
| 1 | WRL-15663 | SparkFun ESP32 Thing Plus WROOM |
| 1 | N/A | peakick PCB assembly |
| 3 | 6 POS 5mm 0.10" receptacle (soldered to peakick PCB) | |
| 3 | 6 POS 0.10" headers | |
| 1 | 1578 | Adafruit 3.7V 500mAH LiPoly rechargeable battery |
| 3 | 1GNL7 | Grainger M2.5 Brass Inserts |
| 3 | M2.5 x 16 mm phillips screws | |
| 1 | N/A | Project enclosure (Top and bottom shells) |
The two boards are interconnected using 0.1" headers and receptacles. The header/receptacle parts were selected to minimize the gap between the two boards and still allow for quick interchange of each board when required. Nylon spacers are used with each of the mounting screws to minimize the effect of shock and vibration in the electrical interconnections.