This project is the third in a series of experimental data loggers for skydivers. This is the first in the series to experiment with the design of real time guidance under canopy and alternatives for displaying those data.
- Sidekick - first project; based on off-the-shelf Adafruit components
- Dropkick - second project; custom PCB experiments with two different u-blox receivers (CAM-M8 and SAM-M8). Ultimately the SAM-M8 delivered better overall reception performance.
The design is composed of two separate modules. A sensor pack gathers data. It uses a Bluetooth interface to send data to the receiving unit. The receiver logs data. It also does some experimental interpretation of the incoming information and uses that to display guidance and other metrics on either an e-Paper or a more traditional TFT LCD display.
| Mfr ID | Manufacturer | Description |
|---|---|---|
| 4062 | Adafruit | Adafruit Feather nRF52840 Express |
| 3775 | Mikroe | 13DOF Click |
| GPS-00177 | SparkFun Electronics | Antenna GPS Embedded SMA |
| GPS-17285 | SparkFun Electronics | GPS Breakout - NEO-M9N, SMA (Qwiic) |
| Mfr ID | Manufacturer | Description |
|---|---|---|
| N/A | LilyGo | LILYGO TTGO T5 V2.2 ESP32 2.9" EPaper Plus Module |
| Mfr ID | Manufacturer | Description |
|---|---|---|
| N/A | LilyGo | LILYGO® TTGO T-WATCH 2020 V2 GPS IPS Open Source ESP32 WIFI Bluetooth Capacitive Touch Screen |
Note: currently LilyGo's web site only shows a V3 watch - I am testing using a V2 version of the product. The V2 version remains listed for sale on the LilyGo sales pages on AliExpress and Banggood.
That's one of the things that I'm working to answer with this project. Overall, e-Paper displays are much slower to update than, say, an OLED or dedicated LCD. By "much", I mean "almost agonizingly much" as the display update time is currently around 300ms in these experiments. Partial updating shows promise, but the stock display management drivers will probably require optimization to work adequately. We'll see.
I used some Google fonts in this project. E-paper bitmaps generated from the Google Comfortaa font are used in the Wrist display project. These fonts are free for commercial use. More information can be found at the Google Fonts web site.
The e-paper graphics library required these fonts be in Adafruit GFX format. I used this excellent web-based converter to generate the GFX files from the original Truetype format distribed by Google: https://rop.nl/truetype2gfx/
Application note: BMI08x FIFO usage