Arduino RF Communication using RX & TX link Modules

hey gareth,

this stuff is awesome!

I have two arduino boards, a sender and reciever like you have used, two servos and a wii nunchuck.

Is it possible to have one board with the nunchuck sending a signal to another which is connect to the servos, thus
being a wireless pan/tilt system using a wii nunchuck??

I really have no idea on how to do this, if you could help me that would be awesome, I have attatched a code which can pan/tilt two servos using the nunchuck one one arduino board all wired up. WOuld you be able to separate these into what i was talking about above?

"#include <Wire.h>
#include <string.h>
#include <stdio.h>

uint8_t outbuf[6];

int cnt = 0;
int ledPin = 13;

int servoPin = 7;
int servoPin2 = 8;

int pulseWidth = 0;
int pulseWidth2 = 0;

long lastPulse = 0;
long lastPulse2 = 0;

int z_button = 0;
int c_button = 0;

int refreshTime = 20;

int minPulse = 1000;
int minPulse2 = 500;

int dtime=10;

#define pwbuffsize 10
long pwbuff[pwbuffsize];
long pwbuffpos = 0;
long pwbuff2[pwbuffsize];
long pwbuffpos2 = 0;

void setup()
{
    Serial.begin (19200);
    Wire.begin ();
    nunchuck_init ();
    pinMode(servoPin, OUTPUT);
    pinMode(servoPin2, OUTPUT);

    pulseWidth = minPulse;
    pulseWidth2 = minPulse2;
    Serial.print ("Finished setup\n");
}

void nunchuck_init()
{
    Wire.beginTransmission (0x52);
    Wire.send (0x40);
    Wire.send (0x00); 
    Wire.endTransmission ();
}

void send_zero()
{
    Wire.beginTransmission (0x52);
    Wire.send (0x00);
    Wire.endTransmission ();
}

int t = 0;

void loop()
{
    t++;
    long last = millis();

    if( t == 1) {

        t = 0;

        Wire.requestFrom (0x52, 6);

        while (Wire.available ()) {
            outbuf[cnt] = nunchuk_decode_byte (Wire.receive ());
            digitalWrite (ledPin, HIGH);
            cnt++;
        }

        if (cnt >= 5) {

            //            printNunchuckData();

            int z_button = 0;
            int c_button = 0;

            if ((outbuf[5] >> 0) & 1)
                z_button = 1;
            if ((outbuf[5] >> 1) & 1)
                c_button = 1;

            switch (c_button) {
            case 1:
                switch (z_button) {
                case 0:
                    break;
                case 1:
                    muovi();
                    break;
                }
                break;
            case 0:
                switch (z_button) {
                case 0:
                    delay(10000);
                    break;
                case 1:
                    delay(3000);
                    break;
                }
                break;
            }
        }

        cnt = 0;
        send_zero();

    } // if(t==)

    updateServo();

    delay(dtime);
}

void updateServo() {

    if (millis() - lastPulse >= refreshTime) {

        digitalWrite(servoPin, HIGH);
        delayMicroseconds(pulseWidth);
        digitalWrite(servoPin, LOW);

        digitalWrite(servoPin2, HIGH);
        delayMicroseconds(pulseWidth2);
        digitalWrite(servoPin2, LOW);

        lastPulse = millis();
    }
}

int i=0;
void printNunchuckData()
{
    int joy_x_axis = outbuf[0];
    int joy_y_axis = outbuf[1];
    int accel_x_axis = outbuf[2]; // * 2 * 2;
    int accel_y_axis = outbuf[3]; // * 2 * 2;
    int accel_z_axis = outbuf[4]; // * 2 * 2;

    int z_button = 0;
    int c_button = 0;

    if ((outbuf[5] >> 0) & 1)
        z_button = 1;
    if ((outbuf[5] >> 1) & 1)
        c_button = 1;
    if ((outbuf[5] >> 2) & 1)
        accel_x_axis += 2;
    if ((outbuf[5] >> 3) & 1)
        accel_x_axis += 1;

    if ((outbuf[5] >> 4) & 1)
        accel_y_axis += 2;
    if ((outbuf[5] >> 5) & 1)
        accel_y_axis += 1;

    if ((outbuf[5] >> 6) & 1)
        accel_z_axis += 2;
    if ((outbuf[5] >> 7) & 1)
        accel_z_axis += 1;

    Serial.print (i,DEC);
    Serial.print ("\t");

    Serial.print ("X: ");
    Serial.print (joy_x_axis, DEC);
    Serial.print ("\t");

    Serial.print ("Y: ");
    Serial.print (joy_y_axis, DEC);
    Serial.print ("\t");

    Serial.print ("AccX: ");
    Serial.print (accel_x_axis, DEC);
    Serial.print ("\t");

    Serial.print ("AccY: ");
    Serial.print (accel_y_axis, DEC);
    Serial.print ("\t");

    Serial.print ("AccZ: ");
    Serial.print (accel_z_axis, DEC);
    Serial.print ("\t");

    Serial.print (z_button, DEC);
    Serial.print (" ");
    Serial.print (c_button, DEC);
    Serial.print ("\r\n");
    i++;
}

char nunchuk_decode_byte (char x)
{
    x = (x ^ 0x17) + 0x17;
    return x;
}

void muovi (){
    float tilt = (700 - outbuf[3]*2*2);
    float tilt2 = outbuf[2]*2*2;

    tilt = (tilt);
    pulseWidth = (tilt * 5) + minPulse;

    tilt2 = (tilt2-288);
    pulseWidth2 = (tilt2 * 5) + minPulse2;

    pwbuff[pwbuffpos] = pulseWidth;
    pwbuff2[pwbuffpos2] = pulseWidth2;
   
    if( ++pwbuffpos == pwbuffsize ) pwbuffpos = 0;
    if( ++pwbuffpos2 == pwbuffsize ) pwbuffpos2 = 0;

    pulseWidth=0;
    pulseWidth2=0;

    for( int p=0; p<pwbuffsize; p++ ){
        pulseWidth += pwbuff[p];
        pulseWidth2 += pwbuff2[p];
    }

    pulseWidth /= pwbuffsize;
    pulseWidth2 /= pwbuffsize;

}

Thanks heaps mate!

Because 23 is the magic number?

Because this post has been collected by 23 members?

Because LMR is 2 years and 3 months old?

First of all: No experience, and currently building my first robot, (the little 8).

Second of All: Thanks for the thorough walkthrough.

Question One: What is the object in the first/top picture on the right with the glowing screen.

Question Two: Can you expand a little on the CD audio trick?

Question Three: Is the antenna sold as 'Antenna' or another kind of wire, also what connects it to the reciever/transmitter?

Question Four: Do you use two identical arduinos, or different ones. Could I use two of these: (http://www.sparkfun.com/commerce/product_info.php?products_id=9152)?

Last Question (probably the dummest): Can PICAXE chips/boards be used??

Noob alert.... can you use the arduino to transmit using the transmitter then have the receiver connected to a usb FTDI serial cable.  then using something like C# to read the serial port and collect what was sent from the transmitter that way?

give me total knowledge which help me  to construct a robot.

thank u 

Gareth:

I've run into trouble using the VirtualWire.h and Servo.h or MegaServo.h.

Seems like there are some conflicts using both those libaries at the same time.
 

C:\Users\Stig\AppData\Local\Temp\untitled30508.tmp\sketch_jan21a\applet\VirtualWire\VirtualWire.cpp.o:E:\Programming\Arduino\hardware\libraries\VirtualWire/VirtualWire.cpp:412: first defined here 

Sketch works fine, but when I add  #include <Servo.h> I get that error.

Gareth:

I've got the 2400bps receiver, so maybe thats why I can't run such high bit.rates?

And yes, I only use the code above, and v1.4 of the libary, only changed what wires to send and receive on.

EDIT:

Tried to modify, so I could store the last message in a char. But somehow it always adds an extra letter.
If the message sent was "LMR" it displays "LMRR".

Seems like the variable message, only gets the last letter stored. how come? Since the code is exactly the same as for the Serial.print.

It has to be something with the for loop, anyone know how to do this? I've also tried sending only numbers trough a int, but seems like thats kind of tricky too.

CODE: http://pastebin.org/57422

1st off..thanks for a great walkthru, Gareth.

I'm ready to go wireless with my Arduino but I haven't decided whether to get a bluetooth module or a couple of RF modules like yours. Allthough the RF's are cheaper and have better range (I think?) I believe I'll go for bluetooth because:

* They're full duplex.

* They're faster (up to 115200 BAUD).

* I can connect it directly to my PC via a dongle, while the RF's would require my PC to be hooked up to ANOTHER MCU.

* They have less dataloss (again I think?).

On the other hand I love cheap lowtech solutions so I might as well get a couple of the RF's as well, since they ARE so damn cheap, plus I'm putting together an order at seeedstudio and they have some similar RF's (both 433 and 315 Mhz).

Anyway thanks for the walkthru. I'll definately use it sooner or later ;)

I had to point one thing out, the Receiver (longer of the two) should *only* be at 5v, where the Transmitter (smaller, obviously :D) can be from 2 - 12v.  Haha, don't try put 12v to the receiver... I have, luckily, it's still alive, but it got really hot, really quick.

But I agree, these things are badass! I didn't even think about getting the 315mhz version for duplex, all though, you can use a transmitter and receiver (of the same frequency) on the same arduino, but I think it's only half-duplex with VirtualWire.  I like your setup :D I just ordered a couple battery holders for the same kind of idea.