Syma Forum

How is the mod coming along, could you post any of your code?

Sorry, i just noticed that there was a question in the opening post that i overlooked :/

the signal in the RFmod is the same as the one from the transmitter, except the 38Khz modulation has been removed, so you are only left with the data packet.

For anyone interested, i have combined some pieces of code to control the S107(+most other 3ch syma helicopters) from an Arduino using 4 Potentiometers, a resistor, and a IR Led. (to keep things simple, i havent used a transistor, but instead used the Arduino to synk the current instead of source it)

This is the best code I have modified so far, however it seems to be missing the code to transmit the check-sum.

Arduino sketch:

// Connect (+) of IR LED to 5Vcc
// connect (-) to pin 4 with a 100 Ohm resistor in line.  For best results make a transistor circuit with external power source.

//Potentiometers connected to analog pins 0, 1, 2, 3  (Throttle, Rudder, Elevator, Trim)
 
#define RED 4    // the output pin of the IR LED
 
void setup() {
    pinMode(RED, OUTPUT);    // set IR LED (Pin 4) to Output
    int ThrottlePin = A0;    // select the input pin for the potentiometer
    int RudderPin = A1;      // select the input pin for the potentiometer
    int ElevatorPin = A2;    // select the input pin for the potentiometer
    int TrimPin = A3;        // select the input pin for the potentiometer
    int Channel = 0;          //Channel A = 0, Channel B = 128
}
 
void loop() {
//Do you magic here.  The code directly below just throttles up to 60 and back down to 0.
//You can get data from the serial port, a joystick, or whatever.  You just need to translate your input into values between 0 and 127.
//Pass those values to Transmit( ) as an integer between 0 and 127 and that's it!
 
    int Throttle, Rudder, Elevator, RudderTrim;
    int Channel;
    
    Throttle = analogRead(A0)/8 + Channel;   //Divide by 2 for difference between CHA and B, Divide by 4 to convert from 10Bit to 8Bit
    Rudder = analogRead(A1)/8 + Channel;   
    Elevator = analogRead(A2)/8 + Channel;   
    RudderTrim = analogRead(A3)/8 + Channel;   
   
    Transmit(Rudder, Elevator, Throttle, RudderTrim);
    
} //End loop()
 
void Transmit(byte rudder, byte elevator, byte throttle, byte trim) {
    static byte Code[4];
    byte mask = 128;     //bitmask
    int i;
 
    Code[0] = rudder; // 0 -> 127; 63 is the midpoint.
    Code[1] = elevator; // 0 -> 127; 63 is the midpoint.
    Code[2] = throttle; // 0 -> 127; 0 is throttle off
    Code[3] = trim;    // Haven't messed with this
     
    OutPulse(2002);  // Start 38Khz pulse for 2000us (2002us is evenly divided by 26)
    delayMicroseconds(2000);  // 2000us off.
 
    for (i = 0; i<4; i++) {        // Loops through the Code[]
        for (mask = 128; mask > 0; mask >>=1) {    // See Arduino reference for bit masking (really cool stuff!)
        OutPulse(312);         // Sends 312 pulse each loop
 
            if(Code[i] & mask) {          //If both bit positions are 1 you get 1             
                delayMicroseconds(688);     // send 1 (700 off)
            }
            else {
                delayMicroseconds(288);     // send 0 (300 off)
            }
        } //End mask loop
    }  //End i loop
 
    OutPulse(312);  //Send 300 microsecond Closing Pulse
    delay(60);      
 
} // End Transmit
 
 
void OutPulse(int Pulse) {  //sends 38Khz pulses over the Pulse Length
    int p;
 
    for(p = 0; p < (Pulse / 26) - 1; p++) {  //Takes about 26 microseconds per loop
        digitalWrite(RED, HIGH);
          delayMicroseconds(10);
        digitalWrite(RED, LOW);
          delayMicroseconds(10);
    }
}  //End OutPulse

Ok, as a wii call of duty kid, I went from "Ok, annother electronics thread that I'm over my head in and it's all gigliboosh to me" to "Ok, this is really cool and interesting."

I'm guessing up will be Z, down C, turn l/r would be l/r on the stick and fwd/bwd would be fwd/bwd on the stick. Just not sure about the trottle exactly...

Do you have a video of the other person't idea? That'd be cool to watch for us laymen!

Waa, I could have sworn I responded to this post.....

Anyway, welcome to the forum, I hope you enjoy your time here.

From reading your post, I assume that you have read the IR protocol thread over at RCGroups to get your code fully working.

To answer your question, the IR receiver removes the 38kHz carrier signal, and inverts the signal (High=0, Low=1) 

Funny thing... just saw an old like 60's oscilloscope at a flea marker last weekend. Lol.

Didn't think there was much use for them anymore besides

Hope everything goes well! Lots of electronics mods now--used to be almost exclusivly mechanical or electric mods. (electric as in different batteries and wiring, not swapping out transmitters and etc)