Last update : 05-February-2008

Radio Controlled Servo Signal Decoder
(Very low power sequential logic switch

This little device (MSP430F1xxx) decodes a R/C servo signal and offers a special kind of sequential logic switch (on/off switch).

There are two options  :

    OPT1 :      0 : Output high if servo signal  < 1.20ms 
                      1 : Output high if servo signal  > 1.80ms
    OPT2 :      0 : Output high any time the RC receiver delivers a signal as  selected by OPT1.
                      1 : Output high, just any second time the RC receiver delivers a signal as described
                            by OPT1.

Control lever          /                 \             /                 \             /                  \                         

   ms                        1.9                  1.1           1.9                  1.1            1.9                  1.1                  
Servo       ________|------|_________|---|_____|------|_________|---|______|------|_________|---|_________

Variometer  _____|XXXXXXXXXX|________|XXXXXXXXXX|________|XXXXXXXXX|____________

GPS-Landing ___________________|XXXXX|_____________________________________|XXXXXXXX
OPT2 = 1 (both units can be turned off)

GPS-Landing ___________________|XXXXX|_______________|XXXXX|_____________|XXXXXXXX
OPT2 = 0 (one unit is always working)

Option OPT2 = 1 allows  turn on and off two units by a single RC-channel independently.
For example if a variometer and a GPS supported landing system should be controlled via a
single channel. The variometer is used during regular flight, the GPSL system is just needed
during  landing.

If the variometer is directly connected to the RC receiver (transmitting if servo signal > 1.8ms)
and the GPS-landing system is connected via a Y-cable and via the RCS device (with settings
OPT1 = 0 and OPT2 = 1), both units can be activated alternatively by a single RC channel.

The everage power is less than 1mA.
The output is availabe as a true and an inverted signal.

Additionally a 31.5 kHz signal is generated to feed external devices (e.g. a pressure sensor).

Here the schematic , just an example how to connect the device (pdf)
The code can be found here.

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