ArduPilot开源飞控之AP_Baro_ExternalAHRS
- 1. 源由
- 2. back-end抽象类
- 3. 方法实现
- 3.1 AP_Baro_ExternalAHRS
- 3.2 update
- 3.3 handle_external
- 3.4 Serial port
- 4. 参考资料
1. 源由
鉴于ArduPilot开源飞控之AP_Baro中涉及Sensor Driver有以下总线类型:
- I2C
- Serial UART
- CAN
- SITL //模拟传感器(暂时并列放在这里)
ArduPilot之开源代码Sensor Drivers设计的front-end / back-end分层设计思路,AP_Baro主要描述的是front-end。
为了更好的从整体理解气压计这个传感器的嵌入式应用,这里深入到back-end驱动层,针对基于串行协议的气压计设备,进行一个研读和理解。
2. back-end抽象类
AP_Baro_Backend
驱动层需实现方法:
- void update()
- static AP_Baro_Backend *probe(AP_Baro &baro, AP_HAL::OwnPtr<AP_HAL::Device> dev)
注:通常来说使用ChibiOS的都有定时器,如果没有定时器,可以使用void accumulate(void)
来实现传感器的数据定时获取。
class AP_Baro_Backend
{
public:
AP_Baro_Backend(AP_Baro &baro);
virtual ~AP_Baro_Backend(void) {};
// each driver must provide an update method to copy accumulated
// data to the frontend
virtual void update() = 0;
// accumulate function. This is used for backends that don't use a
// timer, and need to be called regularly by the main code to
// trigger them to read the sensor
virtual void accumulate(void) {}
void backend_update(uint8_t instance);
// Check that the baro valid by using a mean filter.
// If the value further that filtrer_range from mean value, it is rejected.
bool pressure_ok(float press);
uint32_t get_error_count() const { return _error_count; }
#if AP_BARO_MSP_ENABLED
virtual void handle_msp(const MSP::msp_baro_data_message_t &pkt) {}
#endif
#if AP_BARO_EXTERNALAHRS_ENABLED
virtual void handle_external(const AP_ExternalAHRS::baro_data_message_t &pkt) {}
#endif
/*
device driver IDs. These are used to fill in the devtype field
of the device ID, which shows up as BARO_DEVID* parameters to
users.
*/
enum DevTypes {
DEVTYPE_BARO_SITL = 0x01,
DEVTYPE_BARO_BMP085 = 0x02,
DEVTYPE_BARO_BMP280 = 0x03,
DEVTYPE_BARO_BMP388 = 0x04,
DEVTYPE_BARO_DPS280 = 0x05,
DEVTYPE_BARO_DPS310 = 0x06,
DEVTYPE_BARO_FBM320 = 0x07,
DEVTYPE_BARO_ICM20789 = 0x08,
DEVTYPE_BARO_KELLERLD = 0x09,
DEVTYPE_BARO_LPS2XH = 0x0A,
DEVTYPE_BARO_MS5611 = 0x0B,
DEVTYPE_BARO_SPL06 = 0x0C,
DEVTYPE_BARO_UAVCAN = 0x0D,
DEVTYPE_BARO_MSP = 0x0E,
DEVTYPE_BARO_ICP101XX = 0x0F,
DEVTYPE_BARO_ICP201XX = 0x10,
DEVTYPE_BARO_MS5607 = 0x11,
DEVTYPE_BARO_MS5837 = 0x12,
DEVTYPE_BARO_MS5637 = 0x13,
DEVTYPE_BARO_BMP390 = 0x14,
};
protected:
// reference to frontend object
AP_Baro &_frontend;
void _copy_to_frontend(uint8_t instance, float pressure, float temperature);
// semaphore for access to shared frontend data
HAL_Semaphore _sem;
virtual void update_healthy_flag(uint8_t instance);
// mean pressure for range filter
float _mean_pressure;
// number of dropped samples. Not used for now, but can be usable to choose more reliable sensor
uint32_t _error_count;
// set bus ID of this instance, for BARO_DEVID parameters
void set_bus_id(uint8_t instance, uint32_t id) {
_frontend.sensors[instance].bus_id.set(int32_t(id));
}
};
3. 方法实现
由于气压数据来自串行总线,因此,其逻辑与MSP、CAN协议类似,相对简单,没有校准等复杂物理公式。
3.1 AP_Baro_ExternalAHRS
实例初始化。
AP_Baro_ExternalAHRS::AP_Baro_ExternalAHRS
├──> instance = _frontend.register_sensor();
└──> set_bus_id(instance, AP_HAL::Device::make_bus_id(AP_HAL::Device::BUS_TYPE_SERIAL,port,0,0));
3.2 update
front-end / back-end数据更新。
AP_Baro_ExternalAHRS::update
└──> <count>
├──> WITH_SEMAPHORE(_sem);
├──> _copy_to_frontend(instance, sum_pressure/count, sum_temp/count);
├──> sum_pressure = sum_temp = 0;
└──> count = 0;
3.3 handle_external
处理串行协议中气压和温度数据。
AP_Baro_ExternalAHRS::handle_external
├──> <pkt.instance != 0>
│ └──> return; // not for us
├──> WITH_SEMAPHORE(_sem);
├──> sum_pressure += pkt.pressure_pa;
├──> sum_temp += pkt.temperature;
└──> count++;
3.4 Serial port
串行口驱动数据接收。
AP_Vehicle::setup
└──> AP_ExternalAHRS::init
└──> AP_ExternalAHRS_VectorNav::AP_ExternalAHRS_VectorNav
└──> AP_ExternalAHRS_VectorNav::update_thread //thread_create
└──> AP_ExternalAHRS_VectorNav::check_uart
├──> AP_ExternalAHRS_VectorNav::process_packet1
│ └──> AP_Baro::handle_external
│ └──> AP_Baro_ExternalAHRS::handle_external
└──> AP_ExternalAHRS_VectorNav::process_packet_VN_100
└──> AP_Baro::handle_external
└──> AP_Baro_ExternalAHRS::handle_external
4. 参考资料
【1】ArduPilot开源飞控系统之简单介绍
【2】ArduPilot之开源代码Task介绍
【3】ArduPilot飞控启动&运行过程简介
【4】ArduPilot之开源代码Library&Sketches设计
【5】ArduPilot之开源代码Sensor Drivers设计