Sensors and navigation
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Overview
The PinePhone contains various components that enable or aid orientation and navigation tasks.
Multi-GNSS Receiver as part of the cellular modem (GPS/Galileo/GLONASS/BeiDou)
IMU (Inertial Measurement Unit), combined Accelerometer and Gyroscope sensor (MPU6050)
Magnetometer (LIS3MDL or AF8133J)
Hardware
Invensense/TDK MPU6050 IMU
Key features:
Digital-output X-, Y-, and Z-Axis angular rate sensors (gyroscopes) with selectable range of ±250, ±500, ±1000, and ±2000°/sec
Digital-output triple-axis accelerometer with a programmable full scale range of ±2g, ±4g, ±8g and ±16g
400 kHz Fast Mode I2C for communicating with all registers
ST LIS3MDL Magnetometer/Compass
Key features:
±4/±8/±12/±16 gauss selectable magnetic full scale range
16-bit data output
…
VTC AF8133J Magnetometer/Compass
Key features:
±12/±22 gauss selectable magnetic full scale range
400Hz max. update rate
16-bit data output
Sensor reference frames
The sensors are mounted on the PinePhone’s mainboard in different positions and orientations. For the purpose of orientation and navigation it is important to know the relationship between the sensor coordinate frames and the body frame of the phone.
As a basis for software development, a common body coordinate system has to be established along with it’s relation to a world coordinate system. "iio-sensor-proxy expects the (sensor) readings to match those defined in the Linux IIO documentation, the Windows Integrating Motion and Orientation Sensors whitepaper, and the Android sensor documentation"[ref]. To transform the sensor coordinate systems into body coordinates, 'mount matrices' have to be defined.
TODO: explain body reference choices, north-east-down world coordinates
Software
Drivers
TODO: i2cdev, linux-iio, support matrix
EG25G: provides either UART or USB based interfaces for NMEA data
/dev/ttyUSB2: AT command interface
/dev/ttyUSB1: default NMEA data output
MPU6050:inv_mpu6050, inv_mpu6050_i2c, industrialio
iio:device2: mpu6050 (buffer capable) 9 channels found: accel_x: (input, index: 0, format: be:S16/16>>0) 6 channel-specific attributes found: attr 0: calibbias value: -2102 attr 1: matrix value: 0, 0, 0; 0, 0, 0; 0, 0, 0 attr 2: mount_matrix value: 0, 1, 0; -1, 0, 0; 0, 0, -1 attr 3: raw value: 912 attr 4: scale value: 0.000598 attr 5: scale_available value: 0.000598 0.001196 0.002392 0.004785 accel_y: (input, index: 1, format: be:S16/16>>0) 6 channel-specific attributes found: attr 0: calibbias value: 941 attr 1: matrix value: 0, 0, 0; 0, 0, 0; 0, 0, 0 attr 2: mount_matrix value: 0, 1, 0; -1, 0, 0; 0, 0, -1 attr 3: raw value: 516 attr 4: scale value: 0.000598 attr 5: scale_available value: 0.000598 0.001196 0.002392 0.004785 accel_z: (input, index: 2, format: be:S16/16>>0) 6 channel-specific attributes found: attr 0: calibbias value: 1242 attr 1: matrix value: 0, 0, 0; 0, 0, 0; 0, 0, 0 attr 2: mount_matrix value: 0, 1, 0; -1, 0, 0; 0, 0, -1 attr 3: raw value: 15860 attr 4: scale value: 0.000598 attr 5: scale_available value: 0.000598 0.001196 0.002392 0.004785 temp: (input) 3 channel-specific attributes found: attr 0: offset value: 12420 attr 1: raw value: -1073 attr 2: scale value: 2.941176 anglvel_x: (input, index: 4, format: be:S16/16>>0) 5 channel-specific attributes found: attr 0: calibbias value: 0 attr 1: mount_matrix value: 0, 1, 0; -1, 0, 0; 0, 0, -1 attr 2: raw value: -32 attr 3: scale value: 0.001064724 attr 4: scale_available value: 0.000133090 0.000266181 0.000532362 0.001064724 anglvel_y: (input, index: 5, format: be:S16/16>>0) 5 channel-specific attributes found: attr 0: calibbias value: 0 attr 1: mount_matrix value: 0, 1, 0; -1, 0, 0; 0, 0, -1 attr 2: raw value: 4 attr 3: scale value: 0.001064724 attr 4: scale_available value: 0.000133090 0.000266181 0.000532362 0.001064724 anglvel_z: (input, index: 6, format: be:S16/16>>0) 5 channel-specific attributes found: attr 0: calibbias value: 0 attr 1: mount_matrix value: 0, 1, 0; -1, 0, 0; 0, 0, -1 attr 2: raw value: 0 attr 3: scale value: 0.001064724 attr 4: scale_available value: 0.000133090 0.000266181 0.000532362 0.001064724 timestamp: (input, index: 7, format: le:S64/64>>0) gyro: (input, WARN:iio_channel_get_type()=UNKNOWN) 1 channel-specific attributes found: attr 0: matrix value: 0, 0, 0; 0, 0, 0; 0, 0, 0 3 device-specific attributes found: attr 0: current_timestamp_clock value: realtime attr 1: sampling_frequency value: 50 attr 2: sampling_frequency_available value: 10 20 50 100 200 500 2 buffer-specific attributes found: attr 0: data_available value: 0 attr 1: watermark value: 1 Current trigger: trigger1(mpu6050-dev2)
LIS3MDL: st_sensors, st_sensors_i2c, st_magn, st_magn_i2c, industrialio
iio:device1: lis3mdl (buffer capable) 4 channels found: magn_x: (input, index: 0, format: le:S16/16>>0) 3 channel-specific attributes found: attr 0: raw value: 6766 attr 1: scale value: 0.000146 attr 2: scale_available value: 0.000146 0.000292 0.000438 0.000584 magn_y: (input, index: 1, format: le:S16/16>>0) 3 channel-specific attributes found: attr 0: raw value: -2046 attr 1: scale value: 0.000146 attr 2: scale_available value: 0.000146 0.000292 0.000438 0.000584 magn_z: (input, index: 2, format: le:S16/16>>0) 3 channel-specific attributes found: attr 0: raw value: 12726 attr 1: scale value: 0.000146 attr 2: scale_available value: 0.000146 0.000292 0.000438 0.000584 timestamp: (input, index: 3, format: le:S64/64>>0) 3 device-specific attributes found: attr 0: current_timestamp_clock value: realtime attr 1: sampling_frequency value: 1 attr 2: sampling_frequency_available value: 1 2 3 5 10 20 40 80 2 buffer-specific attributes found: attr 0: data_available value: 0 attr 1: watermark value: 1 Current trigger: trigger0(lis3mdl-trigger)
Tools/Utilities
TODO: minicom, gpsmon, monitor-sensor, iio-utils…
Applications
TODO: pure-maps, navit, …
Development
TODO: Open issues, tasks, projects
Open issues
AGPS integration
how to enable/disable the service?
update triggers?
network connectivity?
agps data valid?
Raw magnetometer handling
Issue: Support polling/non-compensated magnetometers in iio-sensor-proxy
Issue: raw magnetometer calibration implementation
GPS/Compass App
TODO: specification
Frameworks/APIs/…
Modem Manager location API
oFono location API (experimental?)
geoclue API
