GPSLogger

STM32-Arduino-based GPS logger with LCD screen. It is highly inspired by Holux M-241 but with multiple improvements

Key features:

Logging to SD card as raw NMEA dump, as well as ready to use GPX format
Small 128x32 Screen to display various data: current time, horizontal and vertical speed, altitude, odometers, GPS stats and many more
POI button
Multiple odometers with statistics: total and movement time, maximum and average speed, elevation, min/max altitude
- each odometer can be started/paused/resumed/reset independently
Buzzer to inform user about important events
Powered by Lithium battery with working time estimation

More features are TBD

Hardware

Target platform for the project is some kind of STM32 microcontroller - it provides pretty good computation power and enough serial/I2C/SPI ports to connect all the components. Current development goes with stm32f103c8t6 "Blue Pill" arduino-nano-like development board.

Other hardware used:

0.91" OLED 128x32 display
Beitan BN-880 GPS module, based on UBLOX-M8N chip
SD card module TBD
Battery driver module TBD

Connection schematics is TBD. Brief list of connections:

Display is connected to pins B6/B7 (I2C #1)
GPS is connected to A9/A10 (UART #1)
Buttons are connected to C14/C15. Other end is connected to VCC (not GND)

Software used

The device firmware is based on STM32-arduino (stm32duino) framework to access peripheral. At the same time FreeRTOS is used to drive simultaneous and concurrent tasks.

Libraries used:

Adafruit GFX and Adafruit SSD1306 libraries to drive the display
NeoGPS to parse NMEA GPS protocol

The project is using Arduino sketches concept. Atmel Studio + Visual Micro plugin is used to build all the stuff instead of ArduinoIDE. Due to limitations of arduino build process I will likely search for another build system option.

Project Structure

cmake - CMake toolchain files and project wide compiler settings
Docs - various useful docs for project components. Just to keep them at a single location
Libs - Used libraries. Used mostly a copy of original libraries, but have some minor tweaks and configuration changes
Fonts - sources for fonts used in the project
Src - logger sources
Test - unit test and other testing related stuff

How to build

CMake is used as a build system. Here is an example how to generate MinGW makefiles

mkdir <Builddir>
cd <Builddir>
cmake "-DTOOLCHAIN_PREFIX=<PathToArmGccCompiler>" -G "MinGW Makefiles" <PathToProject>
mingw32-make GPSLogger.bin

UI structure

Key part of the system is display. All available information is structured to a screen page concept (or just Screen), each displays a specific set of data.

From the C++ prospective each screen is a class derived from Screen interface. Each class knows how to display itself and implements a reaction on buttons.

Navigation is performed via 2 hardware buttons. Each screen shows a brief tooltip under the button. Typical buttons functionality:

Select button switches to a next screen or value
Ok button applies selected option or enters a submenu/subscreen

Main screens are:

Time Screen displays current time according to selected time zone
- Ok button enters time zone selection screen
Current speed screen displays speed in selected units (km/h, mph), heading and altitude
- Ok button leads to altutude and vertical speed screen
Current position screen shows latitude/longtitude position as Degrees/Minutes/Seconds
- Ok buttons stores current position as a way point (POI)
Odometer screen displays main and additional odometer values
- Long press of Ok button leads to pause/resume/reset selector. Applies to all odometers at once.
  - Reset has a warning message that all metrics will be lost and therefore has additional confirmation
- Ok button leads to odometer selection. Each screen has detailed odometer information such as:
  - Distance
  - Overall duration, active (non-paused) duration
  - total average, active average and maximum speeds
  - elevation (difference between starting and resulting altitude), average active vertical speed
  - Sel button selects the odometers
  - Long Ok button leads to pause/resume/reset selector
    - Reset shows additional confirmation
Settings is a set of options split by categories (selected with 'sel' button)
- GPS Settings - various GPS options (instant GPS signal metrics, distance units selection, etc)
- SD Card - options related to SD card handling (free space metrics, raw log enable/disable, gpx store frequency)
- System - system wide settings (language, display off timings, etc)

Links and misc stuff

Build log with detailed description of goals, achievements, HW and SW solutions, etc. (in Russian):
- Part1
- Part2
- other parts are coming

grafalex82 / GPSLogger