Modules Reference: Driver
This module is responsible for driving the output and reading the input pins. For boards without a separate IO chip (eg. Pixracer), it uses the main channels. On boards with an IO chip (eg. Pixhawk), it uses the AUX channels, and the px4io driver is used for main ones.
It listens on the actuator_controls topics, does the mixing and writes the PWM outputs. In addition it does the RC input parsing and auto-selecting the method. Supported methods are:
The module is configured via mode_* commands. This defines which of the first N pins the driver should occupy. By using mode_pwm4 for example, pins 5 and 6 can be used by the camera trigger driver or by a PWM rangefinder driver. Alternatively, the fmu can be started in one of the capture modes, and then drivers can register a capture callback with ioctl calls.
By default the module runs on the work queue, to reduce RAM usage. It can also be run in its own thread, specified via start flag -t, to reduce latency. When running on the work queue, it schedules at a fixed frequency, and the pwm rate limits the update rate of the actuator_controls topics. In case of running in its own thread, the module polls on the actuator_controls topic. Additionally the pwm rate defines the lower-level IO timer rates.
It is typically started with:
To drive all available pins.
Capture input (rising and falling edges) and print on the console: start the fmu in one of the capture modes:
This will enable capturing on the 4th pin. Then do:
pwm command for further configurations (PWM rate, levels, ...), and the
mixer command to load
fmu <command> [arguments...] Commands: start Start the task (without any mode set, use any of the mode_* cmds) [-t] Run as separate task instead of the work queue All of the mode_* commands will start the fmu if not running already mode_gpio mode_rcin Only do RC input, no PWM outputs mode_pwm Select all available pins as PWM mode_pwm1 mode_pwm4 mode_pwm2 mode_pwm3 mode_pwm3cap1 mode_pwm2cap2 mode_serial mode_gpio_serial mode_pwm_serial mode_pwm_gpio bind Send a DSM bind command (module must be running) sensor_reset Do a sensor reset (SPI bus) [<ms>] Delay time in ms between reset and re-enabling peripheral_reset Reset board peripherals [<ms>] Delay time in ms between reset and re-enabling i2c Configure I2C clock rate <bus_id> <rate> Specify the bus id (>=0) and rate in Hz test Test inputs and outputs fake Arm and send an actuator controls command <roll> <pitch> <yaw> <thrust> Control values in range [-100, 100] stop status print status info
GPS driver module that handles the communication with the device and publishes the position via uORB. It supports multiple protocols (device vendors) and by default automatically selects the correct one.
The module supports a secondary GPS device, specified via
-e parameter. The position will be published
on the second uORB topic instance, but it's currently not used by the rest of the system (however the
data will be logged, so that it can be used for comparisons).
There is a thread for each device polling for data. The GPS protocol classes are implemented with callbacks so that they can be used in other projects as well (eg. QGroundControl uses them too).
For testing it can be useful to fake a GPS signal (it will signal the system that it has a valid position):
gps stop gps start -f
gps <command> [arguments...] Commands: start [-d <val>] GPS device values: <file:dev>, default: /dev/ttyS3 [-e <val>] Optional secondary GPS device values: <file:dev> [-f] Fake a GPS signal (useful for testing) [-s] Enable publication of satellite info [-i <val>] GPS interface values: spi|uart, default: uart [-p <val>] GPS Protocol (default=auto select) values: ubx|mtk|ash stop status print status info
Mount (Gimbal) control driver. It maps several different input methods (eg. RC or MAVLink) to a configured output (eg. AUX channels or MAVLink).
Documentation how to use it is on the gimbal_control page.
Each method is implemented in its own class, and there is a common base class for inputs and outputs.
They are connected via an API, defined by the
ControlData data structure. This makes sure that each input method
can be used with each output method and new inputs/outputs can be added with minimal effort.
Test the output by setting a fixed yaw angle (and the other axes to 0):
vmount stop vmount test yaw 30
vmount <command> [arguments...] Commands: start test Test the output: set a fixed angle for one axis (vmount must not be running) roll|pitch|yaw <angle> Specify an axis and an angle in degrees stop status print status info