fetcher

A process for fetching data from sensors using the I2C protocol.

Usage

See the help documentation with the command: use fetcher.

The output of fetcher looks like:

Time: 1295 ms
Temperature: 25.02 C
Pressure: 99.94 kPa
...

Sensor data output can either be printed in plain-text, or it can be read from the named message queue fetcher/sensors.

Messages on the message queue start with a one-byte type specifier which is one of the following:

/** Describes possible data types that fetcher is capable of producing. */
typedef enum {
    TAG_TEMPERATURE = 0,      /**< Temperature in degrees Celsius */
    TAG_PRESSURE = 1,         /**< Pressure in kilo Pascals */
    TAG_HUMIDITY = 2,         /**< Humidity in % relative humidity */
    TAG_TIME = 3,             /**< Time in milliseconds */
    TAG_ALTITUDE_SEA = 4,     /**< Altitude above sea level in meters */
    TAG_ALTITUDE_REL = 5,     /**< Altitude above launch height in meters */
    TAG_ANGULAR_VEL = 6,      /**< Angular velocity in degrees per second */
    TAG_LINEAR_ACCEL_REL = 7, /**< Relative linear acceleration in meters per second squared */
    TAG_LINEAR_ACCEL_ABS = 8, /**< Absolute linear acceleration in meters per second squared */
} SensorTag;

Followed by data representing the measurement.

Temperature, pressure, humidity and altitude are floats. Time is a 32 bit integer. Linear acceleration and angular velocity are 3D vectors (vec3d_t) of 3 floats.

Board ID EEPROM Encoding

In order for fetcher to recognize the sensors on the board, the EEPROM must encode the ID in this format:

CU InSpace <board name>
REV <x>: <manufacture date>
<sensor 1 id> <address>
<sensor 2 id> <address> <address2>

Fields:

• <board name>: The name of the board. Ex: Sensor board
• REV <x>: The revision of the board. Ex: REV B
• <sensor id>: The identifier of the sensor. Ex: MS5611
• <address>: The 7 bit I2C address of the sensor in hexadecimal (without the leading 0x). Ex: 77
  • It is possible to have more than one address per sensor type for boards with duplicates