watchos

A simple framework for developing on the Sqfmi Watchy.

The goal is to allow more succinct, modular code such that:

• components developed separately can be more easily composed in a single program
• programs can be developed more easily without as much deep technical knowledge of the hardware

It is a work in progress.

Features

• Power management system to extend battery life
• Event system for decoupled tasks/modules
• Basic memory management of core objects
• Task coordination and persistent storage

Components

Kernel

The kernel is the core of watchos. It handles memory management and coordinating modules, tasks, events, and other key components.

Event System

Tasks can subscribe to specific classes of events published by modules to receive events from the rest of the system through a well-defined interface.

Memory Management

Objects can be registered with the kernel to provide reference counting and collection.

Input

The input system abstracts away the hardware inputs and integrates them into the event system while providing basic functionality like debouncing.

Power

The power system monitors for input events and, when the system is idle, automatically puts the system into light and deep sleep, coordinating with all tasks to preserve state.

RTC

The RTC system configures the Watchy's real time clock and provides an interface for fetching data from it, as well as generating events when the time changes.

Storage

The storage system provides a unified interface to different classes of storage, providing persistence for data during sleeps and reboots.

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NOTE: This is not fully implemented yet. The storage module currently only provides an interface to RTC RAM. The plan is to allow specifying and automatically managing other storage classes such as flash storage.

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UI

The UI system provides an interface to register windows which are then automatically laid out according to a few simple layout modes. The UI system provides a abstract interface to the underlying GFX library.

Arduino IDE

Development is primarily done with Visual Studio and the Visual Micro extension. I do try and make sure not to use any Visual Studio-specific features and occassionally attempt to compile it with the Arduino IDE.

However, watchos does make use of the run time type information which is disabled by default in the ESP32 package installed through the board manager in the Arduino IDE.

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You cannot compile this project with the Arduino IDE unless you enable RTTI per the instructions below.

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Enabling RTTI

Locate the hardware folder for your installation, generally on Windows somewhere like:

%LOCALAPPDATA%\arduino15\packages\esp32\hardware\esp32\

Go into the versioned folder under that path. You should see, among other things, a file called platform.txt. Create a new file called platform.local.txt with the contents:

compiler.cpp.flags=-std=gnu++11 -Os -g3 -Wpointer-arith -fexceptions -fstack-protector -ffunction-sections -fdata-sections -fstrict-volatile-bitfields -mlongcalls -nostdlib {compiler.warning_flags} -Wno-error=maybe-uninitialized -Wno-error=unused-function -Wno-error=unused-but-set-variable -Wno-error=unused-variable -Wno-error=deprecated-declarations -Wno-unused-parameter -Wno-unused-but-set-parameter -Wno-missing-field-initializers -Wno-sign-compare -MMD -c

(Note: This is simply the existing cpp.flags setting from platform.txt with the -fno-rtti flag removed. It may be worthwhile to copy the flags from platform.txt and remove that rather than using the above in case you're using a different version of the board package.)

Caveat

Arduino IDE provides no way to adjust these settings on a per-project basis, so this will enable RTTI for all programs you compile for the ESP32 platform.

This should generally have a very negligable impact, but will slightly increase memory usage at runtime.

One day when I actually C++ I'll look at getting rid of the need for RTTI.

License

GPLv3

watchos: platform for Sqfmi's Watchy
Copyright (C) 2021 Adam Pippin

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License version 3 as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.