How to send RPM data as analog input from arduino to Xbee

Question

I am new to arduino and Xbee these stuff. Trying to send RPM (obtained and calculated by arduino using puulse function) data from arduino to Xbee as analog input to xbee series1.

It seems XBee analog input read a range of 0 volts to 1.2 volts. However, not quite sure how to implement and write the corret code. Following are Arduino code and schematic circuit. Any idea? I really appreciate your help.

int pin = 7;  //7
float rpm;
float duration;
float y;

unsigned long val;
float rps;
float read_rpm;
int pin_out=10;


void setup()
{
   Serial.begin(9600);
  pinMode(pin, INPUT);
  pinMode(pin_out,OUTPUT);
}

void loop()
{
 val =  pulseIn(pin, LOW,70000000);

 duration=(float)val/1000000.00;
 rps= 1.00/duration;
rpm=60.00*rps;

analogWrite(pin_out,(int)rpm);

Serial.print("RPM=\t");

Serial.print(rpm);


Serial.print("\t rps= \t");

Serial.print(rps);

Serial.print("\t dt=\t");

Serial.println(val);

}

Answer 1

I would suggest you to send bytes instead of "analog value". When you calculate your value, not sure why you use float and then convert it to int, but here is how i would do. Communicate to xbee via serial communication, send bytes to xbee(its even easier than "analog value"). Added if statment to print RPM every second.

Here is my code:

#include <SoftwareSerial.h>
/* Serial communication with Xbee.
On Arduino pin 9 is Rx connect to Xbee Tx, 
pin 8 is Txconnect to Xbee Rx*/
SoftwareSerial xbeeSerial(9, 8); // RX, TX

int pin = 7;  //7
float rpm;
float duration;
float y;

unsigned long val,time;
float rps;
float read_rpm;
int pin_out=10;

void setup()  
{
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  pinMode(pin, INPUT);
  pinMode(pin_out,OUTPUT);
  Serial.println("I am ready to send some RPM!");

  // set the data rate for the SoftwareSerial port
  xbeeSerial.begin(9600);
  time = millis();
}

void loop()// run over and over
{
 val =  pulseIn(pin, LOW,70000000);

 duration=(float)val/1000000.00;
 rps= 1.00/duration;
rpm=60.00*rps;

/* Sending float to Xbee
Float is 4 byte size*/
serialFloatPrint(rpm);

int floatToInt = (int)rpm;

/* To send INT to XBEE
Int is 2 byte size*/
xbeeSerial.write(highByte(floatToInt));
xbeeSerial.write(lowByte(floatToInt));

/*Print RPM every second*/
If(millis()-time>1000){
  Serial.print("RPM=\t");
  Serial.print(rpm);
  Serial.print("\t rps= \t");
  Serial.print(rps);
  Serial.print("\t dt=\t");
  Serial.println(val);
  time = millis();
 }
}

void serialFloatPrint(float f) {
  byte * b = (byte *) &f;
  //xbeeSerial.print("f:");
  xbeeSerial.print(b[0]);
  xbeeSerial.print(b[1]);
  xbeeSerial.print(b[2]);
  xbeeSerial.print(b[3]);
  /* DEBUG */
  Serial.println();
  Serial.print(b[0],BIN);
  Serial.print(b[1], BIN);
  Serial.print(b[2], BIN);
  Serial.println(b[3], BIN);
  //*/
}