Equipment Cooling
Control System ECCS
This page is where the strange stuff
starts. If you haven't been to the EFIS page you should go there now. After
viewing these pages you should have an understanding of the unusual needs of
this Rocket. The ECCS Module is a central computer that performs multiple
functions. Originally intended to only to control the computer and display
cooling fans, it has grown into several other functions. The selection of
the Microchip PIC 16F877 processor gave so many additional features that I
thought it a waste to use such a small portion for such a simple task. At
present it does the following:
Monitors CPU temp via DS 1620 Sensor.
Monitors OAT temp via DS 1620 sensor.
Monitors CPU fan 1 RPM for Failure.
Monitors CPU fan 2 RPM for Failure.
Monitors and displays NMEA 0183 bus data.
Uses Hardware PWM for Instrument light dimming.
Operates both CPU fans as needed for cooling.
The source code is written in a compiled high level hardware intensive
language called PICbasic. The brains at Micro Engineering Labs (Jeff Smoyer)
make it all happen. It allows the RISC processor to operate at blistering
speeds with most functions needing only one clock cycle to complete. Even at
a 4 MHz clock it needs slowing down to satisfactorily interact with us slow
humans.
The CPU drives a 2 line LCD display based on the Hitachi 44780 architecture.
That may soon change as recent availabilities of Futaba Vacuum Fluorescent
Displays (VFD) make a brighter, more readable display possible (and I can
see it without glasses). One of the coolest features of the PIC 16F877 is
that it allows the use of a boot loader to program the chip while in
circuit. This allows firmware changes without disassembling anything. This
aircraft has a "data loader" connector located on the main electrical buss
panel. By connecting my laptop to the airplane at this serial connection,
the data can be blasted into the CPU in about 15 seconds.
Check back here often as this is an ongoing affair......
Here is the prototype board
.
Here is the completed module.
All the hardware is done and tested. Should be on easy street from now on
with "easy" software changes that can be done while the thing is installed
in the aircraft.
Below are the five data pages. more may be added as the computer still has
75 % of its available memory still free! sitting next to the red module is
the Garmin GPS-35. This is a complete GPS antenna and all in that tiny
waterproof black housing. It is the heart of this airplanes avionics
system
This is another prototype
display. The final version used a two line futaba VFD as the four line
unit could not be fit into the existing panel space.
Flight testing has
shown this device to be reliable and operate as planned. The software has
been tweaked several times using the boot loader. Even during hot Florida
summer months, the highest display temperature recorded on the ramp has
been 42 deg C.
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