Open Source Flight Intrument Documentation [index]
The following requirements apply to the PDA-POD OSFI instrument. These requirements are in addition to the generic requirements.
The instrument shall provide a serial data interface to a personal data assistant (PDA). This interface may be the same physical port as the PC interface but must be physically seperate from the GPS port.
Through this interface the instrument shall be capable of sending real time flight data to the PDA for processing.
The data shall be sent once per second in NMEA format. The following standard NMEA sentences shall be used to send navigation data.
The proprietary "!W" sentence used by the Cambridge Digital Direct Vario 302 will be used to send air data and instrument settings. The format of that sentence is as follows.
!W,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>*hh<CR><LF>
| <1> | Vector wind direction in degrees |
| <2> | Vector wind speed in 10ths of metres per second |
| <3> | Vector wind age in seconds |
| <4> | Component wind in metres per second + 500 (500 = 0, 495 = 5m/s headwind) |
| <5> | True altitude in metres + 1000 |
| <6> | Instrument QNH setting |
| <7> | True airspeed in 100ths of metres per second |
| <8> | Variometer reading in 20ths of knots + 200 |
| <9> | Averager reading in 20ths of knots + 200 |
| <10> | Relative variometer reading in 20ths of knots + 200 |
| <11> | Instrument MacCready setting in 10ths of knots |
| <12> | Instrument ballast setting in persent of capacity |
| <13> | Instrument bug setting |
| hh | Checksum, XOR of all bytes of the sentence after the '!' and before the '*' |