camera_trigger: module docs for camera trigger driver (#23104)

Tools/px4moduledoc/srcparser.py

@@ -15,7 +15,7 @@ class ModuleDocumentation(object):
     # TOC in https://github.com/PX4/PX4-user_guide/blob/main/en/SUMMARY.md
     valid_categories = ['driver', 'estimator', 'controller', 'system',
                         'communication', 'command', 'template', 'simulation', 'autotune']
-    valid_subcategories = ['', 'distance_sensor', 'imu', 'ins', 'airspeed_sensor',
+    valid_subcategories = ['', 'camera', 'distance_sensor', 'imu', 'ins', 'airspeed_sensor',
                            'magnetometer', 'baro', 'optical_flow', 'rpm_sensor', 'transponder']
 
     max_line_length = 80 # wrap lines that are longer than this

src/drivers/camera_trigger/camera_trigger.cpp

@@ -53,6 +53,7 @@
 #include <mathlib/mathlib.h>
 #include <matrix/math.hpp>
 #include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
+#include <px4_platform_common/module.h>
 #include <systemlib/err.h>
 #include <parameters/param.h>
 
@@ -924,7 +925,45 @@ CameraTrigger::status()
 
 static int usage()
 {
-	PX4_INFO("usage: camera_trigger {start|stop|status|test|test_power}\n");
+	PRINT_MODULE_DESCRIPTION(
+		R"DESCR_STR(
+### Description
+
+Camera trigger driver.
+
+This module triggers cameras that are connected to the flight-controller outputs,
+or simple MAVLink cameras that implement the MAVLink trigger protocol.
+
+The driver responds to the following MAVLink trigger commands being found in missions or recieved over MAVLink:
+
+- `MAV_CMD_DO_TRIGGER_CONTROL`
+- `MAV_CMD_DO_DIGICAM_CONTROL`
+- `MAV_CMD_DO_SET_CAM_TRIGG_DIST`
+- `MAV_CMD_OBLIQUE_SURVEY`
+
+The commands cause the driver to trigger camera image capture based on time or distance.
+Each time an image capture is triggered, the `CAMERA_TRIGGER` MAVLink message is emitted.
+
+A "simple MAVLink camera" is one that supports the above command set.
+When configured for this kind of camera, all the driver does is emit the `CAMERA_TRIGGER` MAVLink message as expected.
+The incoming commands must be forwarded to the MAVLink camera, and are automatically emitted to MAVLink channels
+when found in missions.
+
+The driver is configured using [Camera Trigger parameters](../advanced_config/parameter_reference.md#camera-trigger).
+In particular:
+
+- `TRIG_INTERFACE` - How the camera is connected to flight controller (PWM, GPIO, Seagull, MAVLink)
+- `TRIG_MODE` - Distance or time based triggering, with values set by `TRIG_DISTANCE` and `TRIG_INTERVAL`.
+
+[Setup/usage information](../camera/index.md).
+)DESCR_STR");
+	PRINT_MODULE_USAGE_NAME("camera_trigger", "driver");
+	PRINT_MODULE_USAGE_SUBCATEGORY("camera");
+	PRINT_MODULE_USAGE_COMMAND("start");
+	PRINT_MODULE_USAGE_COMMAND_DESCR("stop","Stop driver");
+	PRINT_MODULE_USAGE_COMMAND_DESCR("status","Print driver status information");
+	PRINT_MODULE_USAGE_COMMAND_DESCR("test","Trigger one image (not logged or forwarded to GCS)");
+	PRINT_MODULE_USAGE_COMMAND_DESCR("test_power","Toggle power");
 	return 1;
 }
 

src/drivers/camera_trigger/interfaces/src/camera_interface.h

@@ -39,8 +39,7 @@
 
 #include <parameters/param.h>
 #include <px4_platform_common/log.h>
-
-#define arraySize(a) (sizeof((a))/sizeof(((a)[0])))
+#include <systemlib/px4_macros.h>
 
 class CameraInterface
 {