Merge branch 'master' into stm

docs/firmware.md

@@ -6,7 +6,7 @@ The firmware is a regular Arduino sketch, and it follows the classic Arduino one
 
 <img src="img/dataflow.svg" width=600 alt="Firmware dataflow diagram">
 
-The main loop is running at 1000 Hz. All the dataflow goes through global variables (for simplicity):
+The main loop is running at 1000 Hz. The dataflow goes through global variables, including:
 
 * `t` *(float)* — current step time, *s*.
 * `dt` *(float)* — time delta between the current and previous steps, *s*.
@@ -14,12 +14,12 @@ The main loop is running at 1000 Hz. All the dataflow goes through global variab
 * `acc` *(Vector)* — acceleration data from the accelerometer, *m/s<sup>2</sup>*.
 * `rates` *(Vector)* — filtered angular rates, *rad/s*.
 * `attitude` *(Quaternion)* — estimated attitude (orientation) of drone.
-* `controlRoll`, `controlPitch`, ... *(float[])* — pilot control inputs, range [-1, 1].
-* `motors` *(float[])* — motor outputs, range [0, 1].
+* `controlRoll`, `controlPitch`, `controlYaw`, `controlThrottle`, `controlMode` *(float)* — pilot control inputs, range [-1, 1].
+* `motors` *(float[4])* — motor outputs, range [0, 1].
 
 ## Source files
 
-Firmware source files are located in `flix` directory. The core files are:
+Firmware source files are located in `flix` directory.
 
 * [`flix.ino`](../flix/flix.ino) — Arduino sketch main file, entry point.Includes some global variable definitions and the main loop.
 * [`imu.ino`](../flix/imu.ino) — reading data from the IMU sensor (gyroscope and accelerometer), IMU calibration.
@@ -28,6 +28,7 @@ Firmware source files are located in `flix` directory. The core files are:
 * [`control.ino`](../flix/control.ino) — control subsystem, three-dimensional two-level cascade PID controller.
 * [`motors.ino`](../flix/motors.ino) — PWM motor output control.
 * [`mavlink.ino`](../flix/mavlink.ino) — interaction with QGroundControl or [pyflix](../tools/pyflix) via MAVLink protocol.
+* [`cli.ino`](../flix/cli.ino) — serial and MAVLink console.
 
 Utility files:
 
@@ -37,20 +38,67 @@ Utility files:
 
 ### Control subsystem
 
-Pilot inputs are interpreted in `interpretControls()`, and then converted to the *control command*, which consists of the following:
+Pilot inputs are interpreted in `interpretControls()`, and then converted to the **control command**, which consists of the following:
 
 * `attitudeTarget` *(Quaternion)* — target attitude of the drone.
 * `ratesTarget` *(Vector)* — target angular rates, *rad/s*.
-* `ratesExtra` *(Vector)* — additional (feed-forward) angular rates , used for yaw rate control in STAB mode, *rad/s*.
+* `ratesExtra` *(Vector)* — additional (feed-forward) angular rates, used for yaw rate control in STAB mode, *rad/s*.
 * `torqueTarget` *(Vector)* — target torque, range [-1, 1].
-* `thrustTarget` *(float)* — collective thrust target, range [0, 1].
+* `thrustTarget` *(float)* — collective motor thrust target, range [0, 1].
 
-Control command is processed in `controlAttitude()`, `controlRates()`, `controlTorque()` functions. Each function may be skipped if the corresponding target is set to `NAN`.
+Control command is handled in `controlAttitude()`, `controlRates()`, `controlTorque()` functions. Each function may be skipped if the corresponding control target is set to `NAN`.
 
 <img src="img/control.svg" width=300 alt="Control subsystem diagram">
 
 Armed state is stored in `armed` variable, and current mode is stored in `mode` variable.
 
-## Building
+### Console
+
+To write into the console, `print()` function is used. This function sends data both to the Serial console and to the MAVLink console (which can be accessed wirelessly in QGroundControl). The function supports formatting:
+
+```cpp
+print("Test value: %.2f\n", testValue);
+```
+
+In order to add a console command, modify the `doCommand()` function in `cli.ino` file.
+
+> [!IMPORTANT]
+> Avoid using delays in in-flight commands, it will **crash** the drone! (The design is one-threaded.)
+>
+> For on-the-ground commands, use `pause()` function, instead of `delay()`. This function allows to pause in a way that MAVLink connection will continue working.
+
+### Parameter subsystem
+
+Parameters subsystem (`parameters.ino`) uses standard [Preferences.h](https://docs.espressif.com/projects/arduino-esp32/en/latest/tutorials/preferences.html) ESP32 library to store parameters in non-volatile memory. Each parameter is a regular global variable, which is registered in the `parameters` array.
+
+To add a new parameter:
+
+1. Define a global variable for the parameter, two types are supported: `float` and `int`.
+2. Add an entry to the `parameters` array, with the parameter name, a pointer to the variable, and optionally a callback function to call when the parameter is changed.
+3. Everything else will be handled automatically.
+
+See examples of adding new parameters in commits: [c434107](https://github.com/okalachev/flix/commit/c434107), [a687303](https://github.com/okalachev/flix/commit/a687303).
+
+> [!NOTE]
+> Since all the parameters are internally stored and passed as floats, the safe range for `int` parameters is -16777216 to 16777215.
+
+## Adding a subsystem
+
+To add a new subsystem:
+
+1. Create a new `*.ino` file for your subsystem.
+2. Define setup and loop functions for the subsystem, for example `setupMySubsystem()` and `loopMySubsystem()`.
+3. Use `Rate` class if you need to limit the loop frequency, for example:
+
+    ```cpp
+    Rate mySubsystemRate(100); // 100 Hz
+
+    void loopMySubsystem() {
+    	if (!mySubsystemRate) return;
+    	// Do something...
+    }
+4. Add setup and loop calls in to `setup()` and `loop()` functions in `flix.ino`.
+
+## Building the firmware
 
 See build instructions in [usage.md](usage.md).