HB100_Radar.ino

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 7, 6, 5, 4);

volatile unsigned long firstPulseTime;
volatile unsigned long lastPulseTime;
volatile unsigned long numPulses;

void isr()
{
 unsigned long now = micros();
 if (numPulses == 1)
 {
   firstPulseTime = now;
 }
 else
 {
   lastPulseTime = now;
 }
 ++numPulses;
}


void setup() {
  Serial.begin(9600);
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.setCursor(0, 0);
  lcd.print("Freq [Hz]:");
  lcd.setCursor(0, 1);
  lcd.print("Vel [m/s]:");
  //pinMode(3, OUTPUT);     // put a PWM signal on pin 3, then we can connect pin 3 to pin 2 to test the counter
  //analogWrite(3, 128);
  
}

// Measure the frequency over the specified sample time in milliseconds, returning the frequency in Hz
float readFrequency(unsigned int sampleTime)
{
 numPulses = 0;                      // prime the system to start a new reading
 attachInterrupt(0, isr, RISING);    // enable the interrupt
 delay(sampleTime);
 detachInterrupt(0);
 return (numPulses < 3) ? 0 : (1000000.0 * (float)(numPulses - 2))/(float)(lastPulseTime - firstPulseTime);
}

void loop() {
  float freq = readFrequency(1000);
  int rssi = analogRead(3);
  //float freq = 5;
  float vel = 0.01424 * freq;  
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(11, 1);
  // print the number of seconds since reset:
  lcd.print(vel);
  lcd.setCursor(11, 0);
  // print the number of seconds since reset:
  lcd.print(freq);
  
  Serial.print(millis());
  Serial.print(",");
  Serial.print(freq);
  Serial.print(",");
  Serial.print(vel);
  Serial.print(",");
  Serial.println(rssi);
  
}