这周水肥测试过程中，需要对主管路的流速做一个定量，通过手动球阀的开合度来调节流量，再用Arduino组合液晶屏（1602）做一个显示。

所需组件

●    水流量传感器（DN50/2寸）

●    Arduino UNO开发板

●    液晶屏（1602）

采购的这种霍尔传感流量计

要找到流量计的参数，不同尺寸有不同脉冲特性，计算公式不同。

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volatile int flow_frequency; // Measures flow sensor pulses

// Calculated litres/hour

float vol = 0.0,l_minute;

unsigned char flowsensor = 2; // Sensor Input

unsigned long currentTime;

unsigned long cloopTime;

#include <LiquidCrystal.h>

LiquidCrystal lcd( 8, 7, 6, 5, 4, 3);

void flow () // Interrupt function

{

   flow_frequency++;

}

void setup()

{

   pinMode(flowsensor, INPUT);

   digitalWrite(flowsensor, HIGH); // Optional Internal Pull-Up

   Serial.begin(9600);

   lcd.begin(16, 2);

   attachInterrupt(digitalPinToInterrupt(flowsensor), flow, RISING); // Setup Interrupt

   lcd.clear();

   lcd.setCursor(0,0);

   lcd.print("Water Flow Meter");

   lcd.setCursor(0,1);

   lcd.print("by AIRMTO");

   currentTime = millis();

   cloopTime = currentTime;

}

void loop ()

{

   currentTime = millis();

   // Every second, calculate and print litres/hour

   if(currentTime >= (cloopTime + 1000))

   {

    cloopTime = currentTime; // Updates cloopTime

    if(flow_frequency != 0){

      // Pulse frequency (Hz) = 7.5Q, Q is flow rate in L/min.

      l_minute = (flow_frequency*60 / 0.2); // (Pulse frequency x 60 min) / 7.5Q = flowrate in L/hour

      lcd.clear();

      lcd.setCursor(0,0);

      lcd.print("Rate: ");

      lcd.print(l_minute);

      l_minute = l_minute/1;

      lcd.setCursor(0,1);

      lcd.print("by AIRMTO L/h");

      flow_frequency = 0; // Reset Counter

    }

    else {

      Serial.println(" flow rate = 0 ");

      lcd.clear();

      lcd.setCursor(0,0);

      lcd.print("Rate: ");

      lcd.print( flow_frequency );

      lcd.print(" L/h");

      lcd.setCursor(0,1);

      lcd.print("by AIRMTO");

    }

   }

}

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