The Paleotechnologist

The first CHComm-based instrument is starting to take shape. A Futaba servo connected to a PIC16F877a (yeah, I know — gross overkill — but it was handy) to make a VSI gauge. At this point, it works intermittently; it seems to only register changes of the hundreds’ place; I really need to get an LCD on it to help diagnose what’s going on.

On the bright side, it’s up to 9600 baud, from 2400, so that helps.

Getting the PIC to properly multitask while communicating with the serial port is an interesting proposition. Right now, the main loop provides constant position pulses to the servo while polling the serial port line every 500us or so, to see if a start bit has been received. I’m leaning towards a 2-MCU solution for each gauge, though — one to handle comms and one to run the servo. That way, the servo MCU would be guaranteed a very short data-update cycle, rather than allowing for a potential stoppage should something happen to the serial line. (Servos act strange when their position pulses are interrupted.)

Just finished testing CH Comm — it works, both with FS2004 and FSX! A whole interesting list of FS data can be exported to the RS232 port in standard format. This should make it fairly straightforward to create PIC-based instruments.

At this point, the next steps are:
* Try to get RS232 comms working reliably at a higher speed than 2400 baud — preferably 115200, even if this means a dedicated MCU to handle the comms (which it probably will.)
* Go through the CH Comm .ini file to pare down the output to what is needed (all this data takes an appreciable fraction of a second to export at the default 9600 baud — which would make for poorly-responding instruments.
* Choose one or two parameters for a PIC to read, and display them on a LCD or via a servo.