原文: http://www.amovauto.com/portal.php?mod=view&aid=132
从上电到执行rcS脚本的过程两块控制板（即fmu和io）上电后分别独立启动并运行各自的code。运行过程为：
(1) 2套stm32_start()分别初始化fmu和io
（链接脚本/ardupilot/modules/PX4Firmware/nuttx-configs/px4fmu-v2/scripts/ld.script，中由ENTRY_POINT(__start)指定；同样，/ardupilot/modules/PX4Firmware/nuttx-configs/px4io-v2/scripts/ld.script，中由ENTRY_POINT(__start)指定；px4使用的是stm32，该入口在stm32_start.c中定义）
__start-- #处理器执行的第一条指令
|
v
stm32_clockconfig()------ #初始化时钟 80003d2: f000 f827 bl 8000424
|
v
rcc_reset() #复位rcc
stm32_stdclockconfig() #初始化标准时钟
rcc_enableperipherals() #使能外设时钟
|
--------------------
|
v
stm32_fpuconfig() #配置fpu，
stm32_lowsetup() #基本初始化串口，之后可以使用up_lowputc()
stm32_gpioinit() #初始化gpio，只是调用stm32_gpioremap()设置重映射
clear bss # 清bss段
up_earlyserialinit() #初始化串口，之后可以使用up_putc()
stm32_boardinitialize()-- #板级初始化
|
v
stm32_spiinitialize() #初始化spi，只是调用stm32_configgpio()设置gpio
stm32_usbinitialize() #初始化usb，只是调用stm32_configgpio()设置gpio
board_led_initialize() #初始化led，只是调用stm32_configgpio()设置gpio
|
--------------------
|
v
(2) 2套os_start()分别初始化nuttx系统
28. os_start()-------------#初始化操作系统 ardupilotmodulesPX4NuttX
uttxschedos_start.c
29. |
30. v
31. dq_init() #初始化各种状态的任务列表（置为null）
32. g_pidhash[i]= #初始化唯一可以确定的元素--进程ID
33. g_pidhash[PIDHASH(0)]= #分配空闲任务的进程ID为0
34. g_idletcb= #初始化空闲任务的任务控制块
35. sem_initialize()-- #初始化信号量
36. |
37. v
38. dq_init() #将信号量队列置为null
39. sem_initholders() #初始化持有者结构以支持优先级继承，
40. |
41. --------
42. |
43. v
44. up_allocate_heap() #分配用户模式的堆（设置堆的起点和大小）
45. kumm_initialize() #初始化用户模式的堆
46. up_allocate_kheap() #分配内核模式的堆，
47. kmm_initialize() #初始化内核模式的堆，
48. task_initialize() #初始化任务数据结构，
49. irq_initialize() #将所有中断向量都指向同一个异常中断处理程序
50. wd_initialize() #初始化看门狗数据结构
51. clock_initialize() #初始化rtc
52. timer_initialize() #配置POSIX定时器
53. sig_initialize() #初始化信号
54. mq_initialize() #初始化命名消息队列
55. pthread_initialize() #初始化线程特定的数据，空函数
56. fs_initialize()--- #初始化文件系统
57. |
58. v
59. sem_init() #初始化节点信号量为1
60. files_initialize() #初始化文件数组，空函数
61. |
62. --------
63. |
64. v
65. net_initialize()-- #初始化网络
66. |
67. v
68. uip_initialize() #初始化uIP层
69. net_initroute() #初始化路由表，
70. netdev_seminit() #初始化网络设备信号量
71. arptimer_init() #初始化ARP定时器
72. |
73. --------
74. |
75. v
76. up_initialize()--- #处理器特定的初始化
77. |
78. v
79. up_calibratedelay()#校准定时器
80. up_addregion() #增加额外的内存段
81. up_irqinitialize() #设置中断优先级，关联硬件异常处理函数
82. up_pminitialize() #初始化电源管理，
83. up_dmainitialize() #初始化DMA，
84. up_timerinit() #初始化定时器中断
85. devnull_register() #注册/dev/null
86. devzero_register() #注册/dev/zero，
87. up_serialinit() #注册串口控制台/dev/console和串口/dev/ttyS0
88. up_rnginitialize() #初始化并注册随机数生成器
89. up_netinitialize() #初始化网络，是arch/arm/src/chip/stm32_eth.c中的
90. up_usbinitialize() #初始化usb驱动，
91. board_led_on() #打开中断使能led，
92. |
93. --------
94. |
95. v
96. lib_initialize() #初始化c库，空函数
97. group_allocate() #分配空闲组
98. group_setupidlefiles() #在空闲任务上创建stdout、stderr、stdin
99. group_initialize() #完全初始化空闲组
100. os_bringup()------ #创建初始任务 os_bringup.c
101. |
102. v
103. KEKERNEL_THREAD() #启动内核工作者线程
104. board_initialize() #最后一刻的板级初始化，nsh未调用
105. TASK_CREATE() #启动默认应用程序 os_bringup.c
106. |
107. --------
108. |
109. v
110. for up_idle() #空闲任务循环
111. |
112. --------------------
113. |
114. v
115. for(;;)
(3) 2套os_bringup()函数分别创建进程并传入进程指针CONFIG_USER_ENTRYPOINT
#ifdef CONFIG_NUTTX_KERNELDEBUGASSERT(USERSPACE->us_entrypoint !=NULL);
taskid =TASK_CREATE("init", SCHED_PRIORITY_DEFAULT,
CONFIG_USERMAIN_STACKSIZE, USERSPACE->us_entrypoint,(FAR char*const*)NULL);#else
taskid =TASK_CREATE("init", SCHED_PRIORITY_DEFAULT,
CONFIG_USERMAIN_STACKSIZE,(main_t)CONFIG_USER_ENTRYPOINT,(FAR char*const*)NULL);
(4) fmu中的config.h文件宏定义
#define CONFIG_USER_ENTRYPOINT nsh_main
io中的config.h文件宏定义
#define CONFIG_USER_ENTRYPOINT user_start
(5) fmu开启nshshell
intnsh_main(int argc,char*argv[]){int exitval =0;int ret;/* Call all C++ static constructors */#if defined(CONFIG_HAVE_CXX) && defined(CONFIG_HAVE_CXXINITIALIZE)up_cxxinitialize();#endif/* Make sure that we are using our symbol take */#if defined(CONFIG_LIBC_EXECFUNCS) && defined(CONFIG_EXECFUNCS_SYMTAB)exec_setsymtab(CONFIG_EXECFUNCS_SYMTAB,0);#endif/* Register the BINFS file system */#if defined(CONFIG_FS_BINFS) && (CONFIG_BUILTIN)
ret =builtin_initialize();if(ret <0){fprintf(stderr,"ERROR: builtin_initialize failed: %d
", ret);
exitval =1;}#endif/* Initialize the NSH library */nsh_initialize();/* If the Telnet console is selected as a front-end, then start the
* Telnet daemon.
*/#ifdef CONFIG_NSH_TELNET
ret =nsh_telnetstart();if(ret <0){/* The daemon is NOT running. Report the the error then fail...
* either with the serial console up or just exiting.
*/fprintf(stderr,"ERROR: Failed to start TELNET daemon: %d
", ret);
exitval =1;}#endif/* If the serial console front end is selected, then run it on this thread */#ifdef CONFIG_NSH_CONSOLE
ret =nsh_consolemain(0,NULL);/* nsh_consolemain() should not return. So if we get here, something
* is wrong.
*/fprintf(stderr,"ERROR: nsh_consolemain() returned: %d
", ret);
exitval =1;#endifreturn exitval;}
io
user_start 负责px4io 基础环境的初始化,包括PWM,串口,ADC 等资源的初始化,最后运行一个死循环,用于处理遥控器输入,与PX4FMU 通信的内容
controls_tick 负责处理遥控器的输入内容,包括SBUS 的处理sbus_input、 SPKT/DSM 的处理dsm_port_input、 PPM 的处理ppm_input
intuser_start(int argc,char*argv[]){/* configure the first 8 PWM outputs (i.e. all of them) */up_pwm_servo_init(0xff);/* run C++ ctors before we go any further */up_cxxinitialize();/* reset all to zero */memset(&system_state,0,sizeof(system_state));/* configure the high-resolution time/callout interface */hrt_init();/* calculate our fw CRC so FMU can decide if we need to update */calculate_fw_crc();/*
* Poll at 1ms intervals for received bytes that have not triggered
* a DMA event.
*/#ifdef CONFIG_ARCH_DMAhrt_call_every(&serial_dma_call,1000,1000,(hrt_callout)stm32_serial_dma_poll,NULL);#endif/* print some startup info */lowsyslog("
PX4IO: starting
");/* default all the LEDs to off while we start */LED_AMBER(false);LED_BLUE(false);LED_SAFETY(false);#ifdef GPIO_LED4LED_RING(false);#endif/* turn on servo power (if supported) */#ifdef POWER_SERVOPOWER_SERVO(true);#endif/* turn off S.Bus out (if supported) */#ifdef ENABLE_SBUS_OUTENABLE_SBUS_OUT(false);#endif/* start the safety switch handler */safety_init();/* initialise the control inputs */controls_init();/* set up the ADC */adc_init();/* start the FMU interface */interface_init();/* add a performance counter for mixing */
perf_counter_t mixer_perf =perf_alloc(PC_ELAPSED,"mix");/* add a performance counter for controls */
perf_counter_t controls_perf =perf_alloc(PC_ELAPSED,"controls");/* and one for measuring the loop rate */
perf_counter_t loop_perf =perf_alloc(PC_INTERVAL,"loop");struct mallinfo minfo =mallinfo();lowsyslog("MEM: free %u, largest %u
", minfo.mxordblk, minfo.fordblks);/* initialize PWM limit lib */pwm_limit_init(&pwm_limit);/*
* P O L I C E L I G H T S
*
* Not enough memory, lock down.
*
* We might need to allocate mixers later, and this will
* ensure that a developer doing a change will notice
* that he just burned the remaining RAM with static
* allocations. We don't want him to be able to
* get past that point. This needs to be clearly
* documented in the dev guide.
*
*/if(minfo.mxordblk <600){lowsyslog("ERR: not enough MEM");
bool phase = false;while(true){if(phase){LED_AMBER(true);LED_BLUE(false);}else{LED_AMBER(false);LED_BLUE(true);}up_udelay(250000);
phase =!phase;}}/* Start the failsafe led init */failsafe_led_init();/*
* Run everything in a tight loop.
*/
uint64_t last_debug_time =0;for(;;){/* track the rate at which the loop is running */perf_count(loop_perf);/* kick the mixer */perf_begin(mixer_perf);if(!(r_setup_features & PX4IO_P_SETUP_FEATURES_ONESHOT)){/*
when in oneshot we don't trigger output
until we get new data from the FMU
*/mixer_tick();}perf_end(mixer_perf);/* kick the control inputs */perf_begin(controls_perf);controls_tick();perf_end(controls_perf);check_reboot();/* check for debug activity (default: none) */show_debug_messages();/* post debug state at ~1Hz - this is via an auxiliary serial port
* DEFAULTS TO OFF!
*/if(hrt_absolute_time()- last_debug_time >(1000*1000)){isr_debug(1,"d:%u s=0x%x a=0x%x f=0x%x m=%u",(unsigned)r_page_setup[PX4IO_P_SETUP_SET_DEBUG],(unsigned)r_status_flags,(unsigned)r_setup_arming,(unsigned)r_setup_features,(unsigned)mallinfo().mxordblk);
last_debug_time =hrt_absolute_time();}if(r_page_setup[PX4IO_P_SETUP_HEATER_DUTY_CYCLE]<= PX4IO_HEATER_MAX){control_IMU_heater(r_page_setup[PX4IO_P_SETUP_HEATER_DUTY_CYCLE]);}else{control_heartbeat_LED();}}}
至此io板启动分析完了，fmu继续分析
(6)nsh_main中
nsh_initialize()初始化nshshell，
nsh_consolemain()执行nshshell
进入nsh_consolemain()
intnsh_consolemain(int argc,char*argv[]){
FAR struct console_stdio_s *pstate =nsh_newconsole();int ret;DEBUGASSERT(pstate);/* Execute the start-up script */#ifdef CONFIG_NSH_ROMFSETC(void)nsh_initscript(&pstate->cn_vtbl);#endif/* Initialize any USB tracing options that were requested */#ifdef CONFIG_NSH_USBDEV_TRACEusbtrace_enable(TRACE_BITSET);#endif/* Execute the session */
ret =nsh_session(pstate);/* Exit upon return */nsh_exit(&pstate->cn_vtbl, ret);return ret;}
(void)nsh_initscript(&pstate->cn_vtbl);初始化nsh脚本
ret = nsh_session(pstate);执行nsh脚本
至此nsh脚本还没有引入，所以需要去寻找nsh脚本是什么，进入nsh_initscript()
#ifdef CONFIG_NSH_ROMFSETCintnsh_initscript(FAR struct nsh_vtbl_s *vtbl){static bool initialized;
bool already;int ret = OK;/* Atomic test and set of the initialized flag */sched_lock();
already = initialized;
initialized = true;sched_unlock();/* If we have not already executed the init script, then do so now */if(!already){
ret =nsh_script(vtbl,"init", NSH_INITPATH);}return ret;}
ret = nsh_script(vtbl, “init”, NSH_INITPATH); //Execute the NSH script at path.
#define NSH_INITPATH CONFIG_NSH_ROMFSMOUNTPT “/” CONFIG_NSH_INITSCRIPT
#define CONFIG_NSH_ROMFSMOUNTPT “/etc”
#define CONFIG_NSH_INITSCRIPT “init.d/rcS”
“/etc”是挂载目录
“init.d/rcS”是rcS路径
因此将”/etc”和”init.d/rcS”路径传入nsh_script()
intnsh_script(FAR struct nsh_vtbl_s *vtbl, FAR constchar*cmd,
FAR constchar*path){
FAR char*fullpath;
FAR FILE *savestream;
FAR char*buffer;
FAR char*pret;int ret = ERROR;/* The path to the script may be relative to the current working directory */
fullpath =nsh_getfullpath(vtbl, path);if(!fullpath){return ERROR;}/* Get a reference to the common input buffer */
buffer =nsh_linebuffer(vtbl);if(buffer){/* Save the parent stream in case of nested script processing */
savestream = vtbl->np.np_stream;/* Open the file containing the script */
vtbl->np.np_stream =fopen(fullpath,"r");if(!vtbl->np.np_stream){nsh_output(vtbl, g_fmtcmdfailed, cmd,"fopen", NSH_ERRNO);/* Free the allocated path */nsh_freefullpath(fullpath);/* Restore the parent script stream */
vtbl->np.np_stream = savestream;return ERROR;}/* Loop, processing each command line in the script file (or
* until an error occurs)
*/do{/* Flush any output generated by the previous line */fflush(stdout);#ifndef CONFIG_NSH_DISABLE_LOOPS/* Get the current file position. This is used to control
* looping. If a loop begins in the next line, then this file
* offset will be needed to locate the top of the loop in the
* script file. Note that ftell will return -1 on failure.
*/
vtbl->np.np_foffs =ftell(vtbl->np.np_stream);
vtbl->np.np_loffs =0;if(vtbl->np.np_foffs <0){nsh_output(vtbl, g_fmtcmdfailed,"loop","ftell", NSH_ERRNO);}#endif/* Now read the next line from the script file */
pret =fgets(buffer, CONFIG_NSH_LINELEN, vtbl->np.np_stream);if(pret){/* Parse process the command. NOTE: this is recursive...
* we got to cmd_sh via a call to nsh_parse. So some
* considerable amount of stack may be used.
*/if((vtbl->np.np_flags & NSH_PFLAG_SILENT)==0){nsh_output(vtbl,"%s", buffer);}
ret =nsh_parse(vtbl, buffer);}}while(pret &&(ret == OK ||(vtbl->np.np_flags & NSH_PFLAG_IGNORE)));/* Close the script file */fclose(vtbl->np.np_stream);/* Restore the parent script stream */
vtbl->np.np_stream = savestream;}/* Free the allocated path */nsh_freefullpath(fullpath);return ret;}
其中nsh_output(vtbl, g_fmtcmdfailed, cmd, “fopen”, NSH_ERRNO);是将脚本打开
ret = nsh_parse(vtbl, buffer);解析脚本
至此分析完了fmu从上电到执行rcS脚本的过程。
从rcS启动到ArduCopter执行setup()、loop()
rcS的命令是nshshell的命令，比如
if rgbled start
先执行rgbled start，再作判断。
rgbled 可以对应到modules/PX4Firmware/Build/px4fmu-v2_APM.build/builtin_commands.c中
该文件在固件编译过程中自动生成，记录着一个名为g_builtin[]的数组，数组所有成员即为飞控上电之后，后台运行的所有应用程序，每个成员均有４个参数，分别为程序名、程序调度优先级、堆栈大小以及程序入口函数。
/* builtin command list - automatically generated, do not edit */#include#includeexternintsercon_main(int argc,char*argv[]);externintserdis_main(int argc,char*argv[]);externintpx4io_main(int argc,char*argv[]);externintmtd_main(int argc,char*argv[]);externintadc_main(int argc,char*argv[]);externintperf_main(int argc,char*argv[]);externintfmu_main(int argc,char*argv[]);externinttone_alarm_main(int argc,char*argv[]);externintArduPilot_main(int argc,char*argv[]);///< --------------------externintpwm_input_main(int argc,char*argv[]);externintnshterm_main(int argc,char*argv[]);externintmixer_main(int argc,char*argv[]);externintuorb_main(int argc,char*argv[]);externintver_main(int argc,char*argv[]);externintusb_connected_main(int argc,char*argv[]);externintbl_update_main(int argc,char*argv[]);externinttop_main(int argc,char*argv[]);externintreboot_main(int argc,char*argv[]);conststruct builtin_s g_builtins[]={{"sercon", SCHED_PRIORITY_DEFAULT,2048, sercon_main},{"serdis", SCHED_PRIORITY_DEFAULT,2048, serdis_main},{"px4io", SCHED_PRIORITY_DEFAULT,1200, px4io_main},{"mtd", SCHED_PRIORITY_DEFAULT, CONFIG_PTHREAD_STACK_DEFAULT, mtd_main},{"adc", SCHED_PRIORITY_DEFAULT, CONFIG_PTHREAD_STACK_DEFAULT, adc_main},{"perf", SCHED_PRIORITY_DEFAULT,1800
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