Been working on a GPS based bike computer with the overall objective of creating and implementing everything with what’s wrong with my current device, the Garmin Forerunner 405CX.
LCD: 2.2" ILI9341 (320x240)
Micro: Arduino Due
1x 25Q128FVSG (16 megabyte) SPI flash, soon to be 1x25Q256FV (32MB)
2GB micro and 128mb standard SD cards.
4x micro-switches for buttons.
Powered from 2x18650 batteries.
10hz internal GPS update rate with 1second or less interval datalogging (Forerunner records once per 6 to 9 seconds) to SD once a predetermined quantity has been reached.
Outputs logs via SerialUSB in either raw form and CSV for processing PC side, or a usable TCX file. Fo r example; for uploading direct to Strava.
Currently there is only one display view but this will change once the buttons (micro switches) are added.
Add a dedicated micro SD reader.
Add the Mag and Gyro sensors for both internal use and data logging.
Investigate using an accelerometer for cadence
Shove a Temp sensor in somewhere.
Bluetooth HC-05 module for Heartrate and/or Andriod accessibility. Could possibly use nRF24AP2 If I want to go the more expensive ANT+ route.
Wifi integration via ESP8266-G (because thats what I’ve got).
PC side software is in a much more completed state than the hardware, given its longer (and previous) development time, as can be viewed from the snapshot images.
Originally I was using a battery taken from a Samsung Galaxy phone (the one with the self-contained NFC coil on the back) with a charge controller and boost converter added. This provided around 2hrs usage on a full charge but with nothing in the way of power management implemented.
Now I’m using two new and rather expensive 18650 2400mah Unicross batteries, which are providing over 10hrs always on (non idle) runtime.
Also have a few 18650 8.4v battery packs to try out.
Notes on attachments:
On the display, the green trace is the route I’ve just cycled today, in 3 second intervals with a 15 sample (1.5s) rolling sample bucket.
Yellow/Red circles are the currently tracked Satellites.
The Red ‘3d’ means I have a 3D Sat fix and that datapoints will not be logged. 2D for 2D fix and green indicates datalogging is enabled. (what not moving logging is disabled).
6.x below that is the accuracy in meters (usually around 0.4 - 0.5m when outdoors).
0 is speed in km/h