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

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)

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.

• 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

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

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)

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