WSM is a model railroad car which measures speed of a train and transmits it via Bluetooth. This repository contains firmware to the device`s main processor ATmega328p.
This firmware is developed in C language, compiled via avr-gcc with help
of make. You may also find tools like avrdude helpful.
$ makeHex files are available in Releases section.
WSM PCB contains programming connector, so you may assemble it and program the processor later.
Currently, EEPROM is not used.
Fuses:
-U lfuse:w:0xed:m -U hfuse:w:0xd9:m -U efuse:w:0xfe:m
$ make fuses
$ make programText editor + make. No more, no less.
There are 4 LEDs on the board (red, yellow, green and blue). Blue LED indicates charging, it is not controlled from CPU. The remaining 3 LEDs are controlled from CPU.
Red, yellow and green LED should flash at start.
- Green LED should blink each 5 s. It indicates normal operation and measuring voltage of the battery.
- Yellow LED changes state each time a rising edge on sensor is measured.
- Red LED should normally be off. When this LED is turned on, the battery is low and only a few minutes of measurement are remaining. When the battery level in critical, the red LED flashes 3 times and the device shuts itself down.
The main core of this FW is measuring of speed. Speed is measured via special ICP capture feature of Atmega328 processor. The processor measures period between two rising edges at optosensor.
The processor remembers count and length of all ticks in last second separated into parts of 100 ms. The speed is sent to PC each 100 ms and is calculated as average tick length over last 1 s. This method is known as sliding window with total length of 1 s and each frame of length 100 ms.
Plus, there is another mechnism, which sets speed to 0 when there is no pulse in last 500 ms.
- Jan Horacek (jan.horacek@kmz-brno.cz)
This application is released under the Apache License v2.0 .