L-1011 Avionics Bending: SFENA HSI and ARINC 429 - Part 10

Good progress on the SFENA HSI integration work. All software pieces are now in place and the HSI can be controlled via x-plane.

HSI Software Integration

While today's posting does not integrate all of the ARINC 429 labels required to run the entire instrument, it uses Label 320 which describes "Magnetic Heading from AHARS".  For the magnetic heading data to arrive at the HSI the following steps have to be taken:

1. The magnetic heading data is extracted from the x-plane flight simulator and stored in a shared memory segment by the TAP process as a floating point number.
2. The ARINC 429 to UDP subsystem picks up the float and converts it to an ARINC 429 encoded BNR. The parity for the ARINC 429 data is computed and the data together with the label sent on via UDP to the HSI driver
3. The HSI driver takes the label and the already ARINC 429 converted data from the UDP packet and queues it to the ARINC 429 adapters high-speed (100Kb/sec) transmit channel
4. The HSI logic translates the data into motor movements and rotates the heading hard to the correct position

All of the above happens once every 50ms to create a smooth movement of the HSI instrument.

The video below is a short demonstration of the end-to-end integration of the SFENA HSI:

Over the next few days I will work on the complete integration of all the data needed to operate all the features of the SFENA HSI.