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MicroDis - * 2005

Story: the good but very old electromechanical instruments from rogerson-cratos and brion leroux where needed to be replaced because more and more the mechanic parts weared out by vibrations and due to the low impedance input, always an extra signal conditioner is needed.

Ticking on the instrument glass like the “barometer” to get the pointer to its correct valiue was really not acceptable. :-)

 

FTI_oldinstrument_600_PICT0098

brion-leroux instrument 25I0-I70 from 1968

To replace the old instruments, i designed the  electronic instrument “MICRODIS” = micro display.  which fits into existing flight test cockpit panels and furthermore which is uncompareable more powerful in display variability than the “old school instruments”.

Features: The microdis has a 100 element bargraph led scale and a 4 digit numeric 7mm display. Microdis is realized based on an ATMega128 Microcontroller, two MICREL led driver chips, two full instrumentation amplifiers from analog devices, providing high Impedance > 1MOhm to adapt easily on any measurement signal offers this instrument a high precision solution.

The scale programmable feature including shifting logarithmic or exponential scales to linear by regression factors including calibration enables less than <0,1% full scale error.

The instrument display is also featured with a artificial and configurable display damping which enables a smooth and stable display of the values but with the fast response of showing values with high dynamic change rate..

Also an auto-dimming function is applied to reduce illumination brightness to ambient values while night flight. The display is also NVG compatible for pilots wearing night vision goggles

power supplies are realized in switched technologies to serve the led driver with 1 amp at 3,3V. instrumentation amplifiers and controller does have separate power supplies to have a quiet supply of the amplifier stages.

Different display modes are programmable, bargraph in 1 or 3 dot or bar mode, coupled to the numeric, and/or separate numeric parameter display for “2in1” 2 parameters on one instrument

the “two in one” display version  is realized for example fuel flow, fule flow  kg/min on bargraph and available amount of consumable fuel on numeric display part.

 

FTI_microdisplay_PICT2628
FTI_microdis_PICT2923
FTI_microdisplay_PICT2625

two microdis as dual use instrument: ( Flight test EC145 T2 )

bargraph engine I and engine II:     Torque meter in %

numeric: engine I and engine II:       T4 burning chamber temperatures

FTI_microdisplay_DSCN4706

the hardware is completely modular, consisting of a set of srewless “press to fit 2 stages PCB set of the display pcb and a mainboard for signal conditioning, a/d conversion and digital processing the code to the display drivers.

Unlike normal electronic PCB design and work, a extended precision in design is necessary to realize a small and smart precision instrument like this. By this construction, it is fully ruggedized for harsh flight test operations.

the instrument is covered by a special de-mirrored glass to have the same quality level like the serial cockpit instruments.

the firmware is completely very comfortable programmed with BASCOM. Bascom is basic language but background based on C Libraries and also assembler, if needed, can easily integrated. Comparing to C, C++ has Bascom for me the ultimate advantage to deal at most times with easy human readable code to which you can recognize years later in case of making modifications also easily. Cryptic C or C++  is nice for programming gods who like to celebrate themself but as one tool from many, for me it is more important to spent my energy “to create” an application and not to fight the half the time with all that uncomfortable things of a so called de facto standard language from the digital stone age.  I prefer to write code focused and spendig my time to be creative and less spending energy to deal with all that cryptical and very different from human communication beeing languages with their pitfalls of incomplete developed syntax. But this time, it is inflationary the huge amount of different programing languages and versions. C or C++ or the popular but very poor Arduino IDE may look nice for mainstream  but for microcontrollers there are better ways to have fun. 

so, on Microdis, any configuration is realizable, even every calibration curve is programmable, that provides a linear scale for easy readings bur you can have non linear scales as well.....

 

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