This is a fully open-source car datalogger that reads engine data using the OBD2 interface in real time and stores it on an SD card. It also stores GPS data. All communication is done directly by the MCU without a translator chip like ELM327 or STN1110. The datalogger supports all CAN and K-Line OBD2 protocols. All hardware fits into an off-the-shelf OBD2 connector enclosure.
This project is available on Github.
While working on a bootloader for a Kinetis KE06 I obviously ran in to the task of having to write the internal flash memory of the microcontroller. Freescale’s driver is over 1500 lines of code, exposes every single bit of the flash controller so the simple operation of erasing a sector and writing to it requires many function calls. I wrote my own driver that is less than 200 lines of code and has everything needed to make a bootloader.
Continue reading “Kinetis E – writing to internal flash”
I bought a pair of ePaper displays from Waveshare with the intent to use them in a wireless sensor network for displaying slowly changing data. The reference code from Waveshare is quite clunky and not so easy to re-use, so I made my own small, portable graphics library and display driver (with ARM Cortex-M in mind).
The library is available on Github.
Continue reading “Waveshare ePaper display library”
Microcontroller systems with graphical displays require a way to display text. In case of alphanumeric displays (like HD44780) it is easy – just send your ASCII bytes to the display. Graphical displays operate on individual pixels, so firmware must generate the graphics and texts on the fly.
In this post I show the complete multi-step process from a TrueType (.ttf) font file to autogenerated C code that can be used by a graphics library to display texts on a microcontroller. All code (including the embedded graphics library) is available on Github.
Continue reading “Making graphics and fonts for embedded systems”