PowerOS

The watch firmware is written in C and compiled with Microchip’s xc8 compiler. Functionality is separated into ‘mode’ applications, with each mode implementing a set of procedures to be run when active. The active mode is changed by the Mode side button, with each press cycling through an array of modes.

Requirements

The following programs are required to build and flash the firmware: - make - xc8 - Microchip’s C compiler for PICx Devices. I use the AUR package microchip-xc8-bin which installs version 2.36 of the compiler. - NOTE: Firmware has been successfully compiled and tested with the latest v2.40. - picchick - Flash PICs using an AVR device. Get it from the repo.

Configuration

Build Options

These options modify things about the firmware at build time and can be found in the Makefile: - LOG_LVL - Sets the amount of logged information. Logs above the specified level are not compiled into the final firmware, so expect things to run differently. A log level of ‘0’ is recommend for builds that are going into a watch for use. - XTAL_FREQ - The frequency in Hertz of the oscillator. Changing this value DOES change the frequency of the internal oscillator!

Library Config

Some libraries have their own configuration options. These can be found in the corresponding heading files: - lib/logging.h - LOGGING_UART_BAUDRATE - The baud rate of the debug UART connection.

Configuring Modes

To configure which modes are built into the firmware, two things need to be changed in mode/mode_config.h 1. mode_app_index - Add or Remove enum values so that MAX_MODES coincides with the length of the mode list. 2. mode_list - This list contains pointers to each mode application that should be compiled in.

Note: All mode source files will still be compiled, but only the selected will be included in the final .hex

Building

Compilation is achieved with the make utility. A run of the make fw command will produce a PowerOS.hex file in the sub-directory build/. The command make clean will delete all built files, and a make fclean will remove all files and created directories. A make clean fw is suggested after changing any macros, to verify everything will be referencing the same value.

make [fw]       # Build firmware with settings defined in Makefile.
make clean      # Remove built firmware files.
make fclean     # Remove all created files and folders.

Flash

The pins needed for ICSP are broken out so any PIC programmer that implements the right protocol can flash the built hex file to the watch.

Python utility picchick is used by the Makefile to flash the firmware. It requires a compatible programmer connected to one of the computer’s (virtual) serial ports. Three connections (not including ground) are required between the programmer and the PowerPIC: MCLR, CLK, and DAT. These connections are broken out in test points that can be accessed with just removing the back of the watch.

Programmer Config

• PROGRAMMER_PORT - Serial port of picchick compatible programmer. e.g. /dev/ttyUSB0 or COM3
• PROGRAMMER_BAUD - Baud rate of programmer serial connection.

make flash      # Flash firmware using picchick, (re)building in necessary.