


        JRCSIM version 1.3 now supports real RC-transmitter boxes !!
        ------------------------------------------------------------


        The latest version (1.3) of JRCSIM now allows you to use YOUR OWN
        RC-transmitter (radio) for controlling the plane.

        By using your own radio, you can use all the facilities it offers,
        such as mixers, dual-rate switched e.t.c. and test the different
        functions without risk of crashing.

        The radio is connected to the printer port with a special cable
        (see below for details).



        Which radios ?
        --------------

        Up to 8 channels are supported, even though JRCSIM v.1.3 only uses
        the first four channels for Aileron/Elevator/Throttle and Rudder.

        Only the "old" Pulse Width Modulated transmitters can be used,
        NOT PCM radios.

        Note also that it requires your radio to have an output for a
        teacher/student cable ("buddy-box").

        When using your radio with the simulator it is recommended that you
        remove the RF module if possible or disable it in some way. Often
        you can just remove the crystal to disable the oscillator. This will
        save battery as well as avoid disturbances.

        To find out whether you radio will work with JRCSIM, make a cable
        according to the instructions below and run the RCTEST program.



        How it works
        ------------

        The output from the radio is a pulse train containing 8 pulses,
        each about 1 - 2 mS in length. The pulse train is repeated every
        20 - 25 mS.

           8 pulses, one for each channel                  next pulse train

        ---| |--| |--| |--| |--| |--| |--| |--| |------ . .  -----| |-
           | |  | |  | |  | |  | |  | |  | |  | |                 | |
           |_|  |_|  |_|  |_|  |_|  |_|  |_|  |_|                 |_|

        Ch  1    2    3    4    5    6    7    8

        The normal length of a single pulse are 1.5 mS. By moving the stick,
        you can change the length of the pulse +/- 0.5 mS.


        The program receives this pulse train on the interrupt line on the
        printer port. Each negative edge fires an interrupt. The program
        then read the current value of the system timer and stores it.
        When a value larger than 5 mS is found, it means that the following
        pulse is the first in a series, and syncronization is achieved.




        Cable Details
        -------------

        Well, if you're lucky, you only need to make this simple connection
        from the trainer output of your transmitter to the printer port of
        your PC.

        MAKE SURE that the output from the radio is not more that about
        5 volts. Otherwise you might damage the printer port. You can
        adjust this by using a few resistors. If you don't know how, see
        the warning below !


                Radio                             PC Printer port

        Trainer output  -----------------------------   Pin 10
                Ground  -----------------------------   Pin 18


        If you're one of the unlucky ones like me, the output is not power-
        full enough to drive the printer port. Then you will have to add
        an ultra advanced hi-tech electronics device, a 74HC14 TTL chip.
        This chip should cost you about 30 cents.


                Radio          74HC14           PC Printer port

                                Pin 14 ---------|----  Pin 1
                                                |----  Pin 14
                                                |----  Pin 16
                                                |----  Pin 17
                                Pin 2 --|
                                Pin 3 --|

        Trainer output  ------- Pin 1
                                Pin 4 ---------------  Pin 10
                Ground  ------- Pin 7 ---------------  Pin 18



        WARNING !!!
        -----------

        If you don't know what a 74HC14 is or don't understand the above
        drawing, then DON'T TRY IT YOURSELF !! Get a friend with some more
        knowledge about electronics to fix it for you.




        If it doesn't work
        ------------------

        The code in JRCSIM and in the RCTEST program assumes that the
        signal from the radio has negative edges on each pulse. If that's
        not the case with your radio, you can try the following :

             Connect Pin 4 and Pin 5 on the 74HC14. Then connect Pin 10
             on the printer port to Pin 6 instead of Pin 4 on the 74HC14.
             This will invert the signal.




