PX4模块设计之二十六：BatteryStatus模块

1. BatteryStatus模块简介

### Description

The provided functionality includes:
- Read the output from the ADC driver (via ioctl interface) and publish `battery_status`.


### Implementation
It runs in its own thread and polls on the currently selected gyro topic.

battery_status <command> [arguments...]
 Commands:
   start

   stop

   status        print status info

注：print_usage函数是具体对应实现。

class BatteryStatus : public ModuleBase<BatteryStatus>, public ModuleParams, public px4::ScheduledWorkItem

注：battery_status模块采用了ModuleBase和WorkQueue设计。

2. 模块入口函数

2.1 主入口battery_status_main

这里比较简单，继承了ModuleBase，由ModuleBase的main来完成模块入口。

battery_status_main
 └──> return BatteryStatus::main(argc, argv)

2.2 自定义子命令custom_command

模块仅支持start/stop/status命令，不支持其他自定义命令。

BatteryStatus::custom_command
 └──> return print_usage("unknown command")

3. BatteryStatus模块重要函数

3.1 task_spawn

这里主要初始化了BatteryStatus对象，后续通过WorkQueue来完成进行轮询。

BatteryStatus::task_spawn
 ├──> BatteryStatus *instance = new BatteryStatus()
 ├──> <instance>
 │   ├──> _object.store(instance)
 │   ├──> _task_id = task_id_is_work_queue
 │   └──> <instance->init()>
 │       └──> return PX4_OK
 ├──> <else>
 │   └──> PX4_ERR("alloc failed")
 ├──> delete instance
 ├──> _object.store(nullptr)
 ├──> _task_id = -1
 └──> return PX4_ERROR

3.2 instantiate

注：鉴于该模块不采用任务(线程)，所以ModuleBase::run_trampoline无需执行，所以可以不实现。

3.3 init

在task_spawn中使用，对_adc_report_sub成员变量进行事件回调注册(当有adc_report消息时，会调用SubscriptionCallbackWorkItem::ScheduleNow，再触发BatteryStatus::Run过程)。

BatteryStatus::init
 └──> return _adc_report_sub.registerCallback()

注：这里真正调用ScheduleNow的不是BatteryStatus类，而是该类内部成员变量_adc_report_sub。

uORB::SubscriptionCallbackWorkItem _adc_report_sub{this, ORB_ID(adc_report)};

3.4 Run

每次WorkQueue执行，会自动调用Run函数，详见：PX4模块设计之十三：WorkQueue设计。

BatteryStatus::Run
 ├──> <should_exit()>
 │   ├──> exit_and_cleanup()
 │   └──> return
 ├──> perf_begin(_loop_perf)
 ├──> parameter_update_poll()  // check parameters for updates
 ├──> adc_poll()  // check battery voltage
 └──> perf_end(_loop_perf)

注：关于adc_report消息的来由，可参考：PX4模块设计之二十四：内部ADC模块。

4. 硬件配置

鉴于当前硬件板子使用的是Holybro Kakute AIO F7，其硬件配置如下：

• boards/holybro/kakutef7/src/board_config.h

86 #define ADC_RSSI_IN_CHANNEL                 /* PC5 */  ADC1_CH(15)
87 #define ADC_BATTERY_VOLTAGE_CHANNEL         /* PC3 */  ADC1_CH(13)
88 #define ADC_BATTERY_CURRENT_CHANNEL         /* PC2 */  ADC1_CH(12)
89 
90 #define ADC_CHANNELS \
91 	((1 << ADC_BATTERY_VOLTAGE_CHANNEL)       | \
92 	 (1 << ADC_BATTERY_CURRENT_CHANNEL)       | \
93 	 (1 << ADC_RSSI_IN_CHANNEL))

• platforms/common/include/px4_platform_common/board_common.h

138 #if !defined(BOARD_NUMBER_BRICKS)
139 #  define BOARD_NUMBER_BRICKS 1
140 #  if !defined(BOARD_ADC_BRICK_VALID)
141 #    define BOARD_ADC_BRICK_VALID (1)
142 #  endif
143 #endif
144
145 #if BOARD_NUMBER_BRICKS == 0
146 /* allow SITL to disable all bricks */
147 #elif BOARD_NUMBER_BRICKS == 1
148 #  define BOARD_BATT_V_LIST       {ADC_BATTERY_VOLTAGE_CHANNEL}
149 #  define BOARD_BATT_I_LIST       {ADC_BATTERY_CURRENT_CHANNEL}
150 #  define BOARD_BRICK_VALID_LIST  {BOARD_ADC_BRICK_VALID}
151 #elif BOARD_NUMBER_BRICKS == 2
152 #  if  defined(BOARD_NUMBER_DIGITAL_BRICKS)
153 #    define BOARD_BATT_V_LIST       {-1, -1}
154 #    define BOARD_BATT_I_LIST       {-1, -1}
155 #  else
156 #    define BOARD_BATT_V_LIST       {ADC_BATTERY1_VOLTAGE_CHANNEL, ADC_BATTERY2_VOLTAGE_CHANNEL}
157 #    define BOARD_BATT_I_LIST       {ADC_BATTERY1_CURRENT_CHANNEL, ADC_BATTERY2_CURRENT_CHANNEL}
158 #  endif
159 #  define BOARD_BRICK_VALID_LIST  {BOARD_ADC_BRICK1_VALID, BOARD_ADC_BRICK2_VALID}
160 #elif BOARD_NUMBER_BRICKS == 3
161 #  define BOARD_BATT_V_LIST       {ADC_BATTERY1_VOLTAGE_CHANNEL, ADC_BATTERY2_VOLTAGE_CHANNEL, ADC_BATTERY3_VOLTAGE_CHANNEL}
162 #  define BOARD_BATT_I_LIST       {ADC_BATTERY1_CURRENT_CHANNEL, ADC_BATTERY2_CURRENT_CHANNEL, ADC_BATTERY3_CURRENT_CHANNEL}
163 #  define BOARD_BRICK_VALID_LIST  {BOARD_ADC_BRICK1_VALID, BOARD_ADC_BRICK2_VALID, BOARD_ADC_BRICK3_VALID}
164 #elif BOARD_NUMBER_BRICKS == 4
165 #  define BOARD_BATT_V_LIST       {ADC_BATTERY1_VOLTAGE_CHANNEL, ADC_BATTERY2_VOLTAGE_CHANNEL, ADC_BATTERY3_VOLTAGE_CHANNEL, ADC_BATTERY4_VOLTAGE_CHANNEL}
166 #  define BOARD_BATT_I_LIST       {ADC_BATTERY1_CURRENT_CHANNEL, ADC_BATTERY2_CURRENT_CHANNEL, ADC_BATTERY3_CURRENT_CHANNEL, ADC_BATTERY4_CURRENT_CHANNEL}
167 #  define BOARD_BRICK_VALID_LIST  {BOARD_ADC_BRICK1_VALID, BOARD_ADC_BRICK2_VALID, BOARD_ADC_BRICK3_VALID, BOARD_ADC_BRICK4_VALID}
168 #else
169 #  error Unsuported BOARD_NUMBER_BRICKS number.
170 #endif
171 
172 /* Choose the source for ADC_SCALED_V5_SENSE */
173 #if defined(ADC_5V_RAIL_SENSE)
174 #define ADC_SCALED_V5_SENSE ADC_5V_RAIL_SENSE
175 #else
176 #  if defined(ADC_SCALED_V5_CHANNEL)
177 #    define ADC_SCALED_V5_SENSE ADC_SCALED_V5_CHANNEL
178 #  endif
179 #endif

5. 总结

模块有对adc数据进行过滤但是命令行没有相应的输出显示，也没有将处理后的adc数据发送到系统中。可能这仅仅如代码中写的，是遗产吧。

platforms/common/include/px4_platform_common/board_common.h

136 /* Legacy default */

6. 参考资料

【1】PX4开源软件框架简明简介
【2】PX4模块设计之十一：Built-In框架
【3】PX4模块设计之十二：High Resolution Timer设计
【4】PX4模块设计之十三：WorkQueue设计
【5】PX4模块设计之十七：ModuleBase模块
【6】PX4 modules_main
【7】PX4模块设计之二十四：内部ADC模块