pixhawk原生码rcS分析

代码执行流程

1.       编译时将cmake/configs/nuttx_px4fmu-v2_default.cmake文件中配置的模块全部编译并烧写到固件中去。

2.       地面站的配置会在flash中生成/fs/mtd_params文件，该文件包含了飞行器的各类信息（机架，校准信息，飞行模式等）。

3.       启动pixhawk，执行/Firmware/ROMFS/px4fmu_common/init.d/rcS，该文件会读入之前生成的参数文件，进而选择执行哪一个脚本文           件。（如选择DJI450机架会执行/Firmware/ROMFS/px4fmu_common/init.d/rc.mc_apps                                                                                       和/Firmware/ROMFS/px4fmu_common/init.d/4011_dji_f450），它们的主要作用为启动飞控所需的各类软件。

4.       不同模块通过uORB通信。

上图形象说明启动流程

以下为代码做了部分注释

rcS

#!nsh
#
# PX4FMU startup script.
#
#  NOTE: COMMENT LINES ARE REMOVED BEFORE STORED IN ROMFS.
#

#
# Start CDC/ACM serial driver
#
sercon

#
# Default to auto-start mode.           //一些默认设置
#
set MODE autostart

set FRC /fs/microsd/etc/rc.txt
set FCONFIG /fs/microsd/etc/config.txt
set TUNE_ERR ML<> $LOG_FILE

			set IO_PRESENT yes
		else
			echo "PX4IO Trying to update" >> $LOG_FILE

			tone_alarm MLL32CP8MB

			if px4io start//启动px4io
			then
				# try to safe px4 io so motor outputs dont go crazy
				if px4io safety_on//判断px4io是否安全
				then
					# success! no-op
				else
					# px4io did not respond to the safety command
					px4io stop
				fi
			fi

			if px4io forceupdate 14662 ${IO_FILE}//是否强制升级
			then
				usleep 500000
				if px4io checkcrc $IO_FILE
				then
					echo "PX4IO CRC OK after updating" >> $LOG_FILE
					tone_alarm MLL8CDE

					set IO_PRESENT yes
				else
					echo "ERROR: PX4IO update failed" >> $LOG_FILE
					tone_alarm $TUNE_ERR
				fi
			else
				echo "ERROR: PX4IO update failed" >> $LOG_FILE
				tone_alarm $TUNE_ERR
			fi
		fi
		unset IO_FILE

		if [ $IO_PRESENT == no ] //没有找到px4io
		then
			echo "[i] ERROR: PX4IO not found"
			echo "ERROR: PX4IO not found" >> $LOG_FILE
			tone_alarm $TUNE_ERR
		fi
	fi

	#
	# Set default output if not set//如果不设置，则为默认设置none
	#
	if [ $OUTPUT_MODE == none ]
	then
		if [ $USE_IO == yes ] //px4的版本为v2，所以条件满足
		then
			set OUTPUT_MODE io
		else
			set OUTPUT_MODE fmu
		fi
	fi

	if [ $OUTPUT_MODE == io -a $IO_PRESENT != yes ]
	then
		# Need IO for output but it not present, disable output//需要IO口输出，但是它不存在
		set OUTPUT_MODE none
		echo "[i] ERROR: PX4IO not found, disabling output"

		# Avoid using ttyS0 for MAVLink on FMUv1
		if ver hwcmp PX4FMU_V1//比较px4的版本
		then
			set FMU_MODE serial  //设置FMU_MODE为serial模式
		fi
	fi

	if [ $OUTPUT_MODE == ardrone ]
	then
		set FMU_MODE gpio_serial
	fi

	if [ $HIL == yes ] //比较HIL参数设置
	then
		set OUTPUT_MODE hil
		set GPS no
		if ver hwcmp PX4FMU_V1
		then
			set FMU_MODE serial
		fi
	fi
	unset HIL

	# waypoint storage      //存储路径
	# REBOOTWORK this needs to start in parallel
	if dataman start
	then
	fi

	#
	# Sensors System (start before Commander so Preflight checks are properly run)
	#//起飞前传感器检查
	sh /etc/init.d/rc.sensors//执行rc.sensors（标准的PX4FMU v1, v2, v3传感器启动脚本）
	
	if [ $GPS == yes ] //检查GPS和GPS_FRAK
	then
		if [ $GPS_FAKE == yes ]
		then
			echo "[i] Faking GPS"
			gps start -f
		else
			gps start
		fi
	fi
	unset GPS
	unset GPS_FAKE

	# Needs to be this early for in-air-restarts
	commander start  //启动commander，类似于任务管理器

	#
	# Start primary output//以下为一系列判断，再启动如何输出
	#
	set TTYS1_BUSY no

	#
	# Check if UAVCAN is enabled, default to it for ESCs//检查UAVCAN是否使能
	#
	if param greater UAVCAN_ENABLE 2 //如果UAVCAN_ENABLE大于2
	then
		set OUTPUT_MODE uavcan_esc
	fi

	# If OUTPUT_MODE == none then something is wrong with setup and we shouldn't try to enable output
	//如果OUTPUT_MODE == none，那么有问题，不能尝试使能输出
	if [ $OUTPUT_MODE != none ]
	then
		if [ $OUTPUT_MODE == uavcan_esc ]
		then
			if param compare UAVCAN_ENABLE 0
			then
				echo "[i] OVERRIDING UAVCAN_ENABLE = 1"
				param set UAVCAN_ENABLE 1
			fi
		fi

		if [ $OUTPUT_MODE == io -o $OUTPUT_MODE == uavcan_esc ]
		then
			if px4io start
			then
				sh /etc/init.d/rc.io//执行rc.io
			else
				echo "ERROR: PX4IO start failed" >> $LOG_FILE
				tone_alarm $TUNE_ERR
			fi
		fi

		if [ $OUTPUT_MODE == fmu -o $OUTPUT_MODE == ardrone ]
		then
			if fmu mode_$FMU_MODE
			then
				echo "[i] FMU mode_$FMU_MODE started"
			else
				echo "[i] ERROR: FMU mode_$FMU_MODE start failed"
				echo "ERROR: FMU start failed" >> $LOG_FILE
				tone_alarm $TUNE_ERR
			fi

			if ver hwcmp PX4FMU_V1
			then
				if [ $FMU_MODE == pwm -o $FMU_MODE == gpio ]
				then
					set TTYS1_BUSY yes
				fi
				if [ $FMU_MODE == pwm_gpio -o $OUTPUT_MODE == ardrone ]
				then
					set TTYS1_BUSY yes
				fi
			fi
		fi

		if [ $OUTPUT_MODE == mkblctrl ]
		then
			set MKBLCTRL_ARG ""
			if [ $MKBLCTRL_MODE == x ]
			then
				set MKBLCTRL_ARG "-mkmode x"
			fi
			if [ $MKBLCTRL_MODE == + ]
			then
				set MKBLCTRL_ARG "-mkmode +"
			fi

			if mkblctrl $MKBLCTRL_ARG
			then
				echo "[i] MK started"
			else
				echo "[i] ERROR: MK start failed"
				echo "ERROR: MK start failed" >> $LOG_FILE
				tone_alarm $TUNE_ERR
			fi
			unset MKBLCTRL_ARG
		fi
		unset MK_MODE

		if [ $OUTPUT_MODE == hil ]
		then
			if pwm_out_sim mode_port2_pwm8
			then
				echo "[i] PWM SIM output started"
			else
				echo "[i] ERROR: PWM SIM output start failed"
				echo "ERROR: PWM SIM output start failed" >> $LOG_FILE
				tone_alarm $TUNE_ERR
			fi
		fi

		#
		# Start IO or FMU for RC PPM input if needed//如果需要，则启动IO和FMU接收PPM
		#
		if [ $IO_PRESENT == yes ]
		then
			if [ $OUTPUT_MODE != io ]
			then
				if px4io start
				then
					echo "[i] PX4IO started"
					sh /etc/init.d/rc.io
				else
					echo "[i] ERROR: PX4IO start failed"
					echo "ERROR: PX4IO start failed" >> $LOG_FILE
					tone_alarm $TUNE_ERR
				fi
			fi
		else
			if [ $OUTPUT_MODE != fmu -a $OUTPUT_MODE != ardrone ]
			then
				if fmu mode_$FMU_MODE
				then
					echo "[i] FMU mode_$FMU_MODE started"
				else
					echo "[i] ERROR: FMU mode_$FMU_MODE start failed"
					echo "ERROR: FMU mode_$FMU_MODE start failed" >> $LOG_FILE
					tone_alarm $TUNE_ERR
				fi

				if ver hwcmp PX4FMU_V1
				then
					if [ $FMU_MODE == pwm -o $FMU_MODE == gpio ]
					then
						set TTYS1_BUSY yes
					fi
					if [ $FMU_MODE == pwm_gpio -o $OUTPUT_MODE == ardrone ]
					then
						set TTYS1_BUSY yes
					fi
				fi
			fi
		fi
	fi
//以下为mavlink的设置
	if [ $MAVLINK_F == default ]
	then
		# Normal mode, use baudrate 57600 (default) and data rate 1000 bytes/s
		if [ $TTYS1_BUSY == yes ]
		then
			# Start MAVLink on ttyS0, because FMU ttyS1 pins configured as something else
			set MAVLINK_F "-r 1200 -d /dev/ttyS0"

			# Exit from nsh to free port for mavlink
			set EXIT_ON_END yes
		else
			set MAVLINK_F "-r 1200"
			# Avoid using ttyS1 for MAVLink on FMUv4
			if ver hwcmp PX4FMU_V4
			then
				set MAVLINK_F "-r 1200 -d /dev/ttyS1"
				# Start MAVLink on Wifi (ESP8266 port)
				mavlink start -r 20000 -m config -b 921600 -d /dev/ttyS0
			fi
		fi
	fi

	mavlink start $MAVLINK_F
	unset MAVLINK_F

	#
	# MAVLink onboard / TELEM2
	#
	if ver hwcmp PX4FMU_V1
	then
	else
		# XXX We need a better way for runtime eval of shell variables,
		# but this works for now
		if param compare SYS_COMPANION 921600
		then
			mavlink start -d /dev/ttyS2 -b 921600 -m onboard -r 80000 -x
		fi
		if param compare SYS_COMPANION 57600
		then
			mavlink start -d /dev/ttyS2 -b 57600 -m onboard -r 5000 -x
		fi
		if param compare SYS_COMPANION 157600
		then
			mavlink start -d /dev/ttyS2 -b 57600 -m osd -r 1000
		fi
		if param compare SYS_COMPANION 257600
		then
			mavlink start -d /dev/ttyS2 -b 57600 -m magic -r 5000 -x
		fi
		if param compare SYS_COMPANION 357600
		then
			mavlink start -d /dev/ttyS2 -b 57600 -r 1000
		fi
		# Sensors on the PWM interface bank
		# clear pins 5 and 6
		if param compare SENS_EN_LL40LS 1
		then
			set AUX_MODE pwm4
		fi
		if param greater TRIG_MODE 0
		then
			# Get FMU driver out of the way
			set MIXER_AUX none
			set AUX_MODE none
			camera_trigger start
		fi
	fi

	# Transitional support: Disable safety on all Pixracer boards
	if ver hwcmp PX4FMU_V4
	then
		param set CBRK_IO_SAFETY 22027
	fi

	#
	# UAVCAN
	#
	sh /etc/init.d/rc.uavcan//执行rc.uavcan，也就是启动rc.uavcan

	#
	# Logging
	#
	sh /etc/init.d/rc.logging//执行rc.logging，也就是启动rc.logging

	#
	# Start up ARDrone Motor interface
	#
	if [ $OUTPUT_MODE == ardrone ]
	then
		ardrone_interface start -d /dev/ttyS1
	fi

	#
	# Fixed wing setup//固定翼的设置
	#
	if [ $VEHICLE_TYPE == fw ]
	then
		echo "[i] FIXED WING"

		if [ $MIXER == none ]
		then
			# Set default mixer for fixed wing if not defined
			set MIXER AERT
		fi

		if [ $MAV_TYPE == none ]
		then
			# Use MAV_TYPE = 1 (fixed wing) if not defined
			set MAV_TYPE 1
		fi

		param set MAV_TYPE $MAV_TYPE

		# Load mixer and configure outputs
		sh /etc/init.d/rc.interface//执行rc.interface，配置控制接口

		# Start standard fixedwing apps
		if [ $LOAD_DAPPS == yes ]
		then
			sh /etc/init.d/rc.fw_apps//执行rc.fw_apps，开启姿态和位置估算
		fi
	fi

	#
	# Multicopters setup//多旋翼的设置
	#
	if [ $VEHICLE_TYPE == mc ]
	then
		echo "[i] MULTICOPTER"

		if [ $MIXER == none ]
		then
			echo "Mixer undefined"
		fi

		if [ $MAV_TYPE == none ]//根据用户的选择，设置MAV_TYPE
		then
			# Use mixer to detect vehicle type
			if [ $MIXER == quad_x -o $MIXER == quad_+ ]
			then
				set MAV_TYPE 2
			fi
			if [ $MIXER == quad_w -o $MIXER == sk450_deadcat ]
			then
				set MAV_TYPE 2
			fi
			if [ $MIXER == quad_h ]
			then
				set MAV_TYPE 2
			fi
			if [ $MIXER == tri_y_yaw- -o $MIXER == tri_y_yaw+ ]
			then
				set MAV_TYPE 15
			fi
			if [ $MIXER == hexa_x -o $MIXER == hexa_+ ]
			then
				set MAV_TYPE 13
			fi
			if [ $MIXER == hexa_cox ]
			then
				set MAV_TYPE 13
			fi
			if [ $MIXER == octo_x -o $MIXER == octo_+ ]
			then
				set MAV_TYPE 14
			fi
			if [ $MIXER == octo_cox -o $MIXER == octo_cox_w ]
			then
				set MAV_TYPE 14
			fi
		fi

		# Still no MAV_TYPE found//mav的类型没找到
		if [ $MAV_TYPE == none ]
		then
			echo "Unknown MAV_TYPE"
			param set MAV_TYPE 2
		else
			param set MAV_TYPE $MAV_TYPE
		fi

		# Load mixer and configure outputs
		sh /etc/init.d/rc.interface//执行rc.interface，配置控制接口

		# Start standard multicopter apps
		if [ $LOAD_DAPPS == yes ]
		then
			sh /etc/init.d/rc.mc_apps// 执行rc.mc_apps，启动姿态位置的估计和控制
		fi
	fi

	#
	# VTOL setup//工具类型设置
	#
	if [ $VEHICLE_TYPE == vtol ]
	then
		echo "[init] Vehicle type: VTOL"

		if [ $MIXER == none ]
		then
			echo "Default mixer for vtol not defined"
		fi

		if [ $MAV_TYPE == none ]
		then
			# Use mixer to detect vehicle type
			if [ $MIXER == caipirinha_vtol ]
			then
				set MAV_TYPE 19
			fi
			if [ $MIXER == firefly6 ]
			then
				set MAV_TYPE 21
			fi
			if [ $MIXER == quad_x_pusher_vtol ]
			then
				set MAV_TYPE 22
			fi
		fi

		# Still no MAV_TYPE found
		if [ $MAV_TYPE == none ]
		then
			echo "Unknown MAV_TYPE"
			param set MAV_TYPE 19
		else
			param set MAV_TYPE $MAV_TYPE
		fi

		# Load mixer and configure outputs
		sh /etc/init.d/rc.interface//执行rc.interface，下载mixer并配置输出

		# Start standard vtol apps
		if [ $LOAD_DAPPS == yes ]
		then
			sh /etc/init.d/rc.vtol_apps//执行rc.vtol_apps，
										//启动attitude_estimator_q start、
										//position_estimator_inav start、
										//vtol_att_control start、
										//mc_att_control start、
										//mc_pos_control start、
										//fw_att_control start、
										//fw_pos_control_l1 start
		fi
	fi

	#
	# Rover setup//漫游设置
	#
	if [ $VEHICLE_TYPE == rover ]
	then
		# 10 is MAV_TYPE_GROUND_ROVER
		set MAV_TYPE 10

		# Load mixer and configure outputs
		sh /etc/init.d/rc.interface//执行rc.interface，下载mixer并配置输出

		# Start standard rover apps
		if [ $LOAD_DAPPS == yes ]
		then
			sh /etc/init.d/rc.axialracing_ax10_apps//ekf_att_pos_estimator start
		fi

		param set MAV_TYPE 10
	fi

	unset MIXER
	unset MAV_TYPE
	unset OUTPUT_MODE

	#
	# Start the navigator//启动导航
	#
	navigator start

	#
	# Generic setup (autostart ID not found) //常规设置
	#
	if [ $VEHICLE_TYPE == none ]
	then
		echo "[i] No autostart ID found"

	fi

	# Start any custom addons   //启动自定义插件
	set FEXTRAS /fs/microsd/etc/extras.txt
	if [ -f $FEXTRAS ]
	then
		echo "[i] Addons script: $FEXTRAS"
		sh $FEXTRAS
	fi
	unset FEXTRAS

	# Run no SD alarm         //运行没有sd卡的警告
	if [ $LOG_FILE == /dev/null ]
	then
		echo "[i] No microSD card found"
		# Play SOS
		tone_alarm error
	fi

# End of autostart
fi

# There is no further script processing, so we can free some RAM
# XXX potentially unset all script variables.
unset TUNE_ERR

# Boot is complete, inform MAVLink app(s) that the system is now fully up and running
mavlink boot_complete

# Sensors on the PWM interface bank     
if param compare SENS_EN_LL40LS 1
then
	if pwm_input start //启动pwm输入设置
	then
		if ll40ls start pwm
		then
		fi
	fi
fi

if ver hwcmp PX4FMU_V4
then
	frsky_telemetry start -d /dev/ttyS6
fi

if ver hwcmp PX4FMU_V2
then
	# Check for flow sensor - as it is a background task, launch it last
	px4flow start & //如果检测到光流，则启动
fi

# Start USB shell if no microSD present, MAVLink else //如果没找到sd卡，则启动usb shell， 
if [ $LOG_FILE == /dev/null ]                         //找到了则启动mavlink
then
	# Try to get an USB console
	nshterm /dev/ttyACM0 &
else
	mavlink start -r 800000 -d /dev/ttyACM0 -m config -x
fi

if [ $EXIT_ON_END == yes ]
then
	echo "Exit from nsh"
	exit
fi
unset EXIT_ON_END

rc.sensors

#!nsh
#
# Standard startup script for PX4FMU v1, v2, v3 onboard sensor drivers.
#

if ver hwcmp PX4FMU_V1  //比较px4版本
then
	if ms5611 start
	then
	fi
else
	if ms5611 -s start
	then
	fi

	# Blacksheep telemetry
	if bst start
	then
	fi
fi

if adc start
then
fi

if ver hwcmp PX4FMU_V2//比较px4版本
then
	# External I2C bus
	if hmc5883 -C -T -X start   //启动hmc5883
	then
	fi

	# Internal I2C bus
	if hmc5883 -C -T -I -R 4 start
	then
	fi

	# external MPU6K is rotated 180 degrees yaw
	if mpu6000 -X -R 4 start
	then
		set BOARD_FMUV3 true
	else
		set BOARD_FMUV3 false
	fi

	if [ $BOARD_FMUV3 == true ]
	then
		# external L3GD20H is rotated 180 degrees yaw
		if l3gd20 -X -R 4 start
		then
		fi

		# external LSM303D is rotated 270 degrees yaw
		if lsm303d -X -R 6 start
		then
		fi

		# internal MPU6000 is rotated 180 deg roll, 270 deg yaw
		if mpu6000 -R 14 start
		then
		fi

		if hmc5883 -C -T -S -R 8 start
		then
		fi

	else
		# FMUv2
		if mpu6000 start
		then
		fi

		if l3gd20 start
		then
		fi

		if lsm303d start
		then
		fi
	fi
else
	if ver hwcmp PX4FMU_V4
	then
		# External I2C bus
		if hmc5883 -C -T -X start
		then
		fi

		# Internal SPI bus is rotated 90 deg yaw
		if hmc5883 -C -T -S -R 2 start
		then
		fi

		# Internal SPI bus ICM-20608-G is rotated 90 deg yaw
		if mpu6000 -R 2 -T 20608 start
		then
		fi

		# Internal SPI bus mpu9250 is rotated 90 deg yaw
		if mpu9250 -R 2 start
		then
		fi
	else
		# FMUv1
		if mpu6000 start
		then
		fi

		if l3gd20 start
		then
		fi

		# MAG selection
		if param compare SENS_EXT_MAG 2
		then
			if hmc5883 -C -I start
			then
			fi
		else
			# Use only external as primary
			if param compare SENS_EXT_MAG 1
			then
				if hmc5883 -C -X start
				then
				fi
			else
			# auto-detect the primary, prefer external
				if hmc5883 start
				then
				fi
			fi
		fi
	fi
fi

if meas_airspeed start
then
else
	if ets_airspeed start
	then
	else
		if ets_airspeed start -b 1
		then
		fi
	fi
fi

if sf10a start
then
fi

# Wait 20 ms for sensors (because we need to wait for the HRT and work queue callbacks to fire)
usleep 20000
if sensors start
then
fi

rc.mc_apps

#!nsh
#
# Standard apps for multirotors:
# att & pos estimator, att & pos control.
#

# The system is defaulting to INAV_ENABLED = 1
# but users can alternatively try the EKF-based
# filter by setting INAV_ENABLED = 0
//选择姿态位置估计和控制使用的算法，默认INAV_ENABLED = 1，那么
姿态估计 Attitude_estimator_q
位置估计 position_estimator_inav
姿态控制 mc_att_control
位置控制 mc_pos_control
if param compare INAV_ENABLED 1
then
	attitude_estimator_q start
	position_estimator_inav start
else
	if param compare LPE_ENABLED 1
	then
		attitude_estimator_q start
		local_position_estimator start
	else
		ekf2 start
	fi
fi

if mc_att_control start
then
else
	# try the multiplatform version
	mc_att_control_m start
fi

if mc_pos_control start
then
else
	# try the multiplatform version
	mc_pos_control_m start
fi

#
# Start Land Detector
#
land_detector start multicopter

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