Thank you very much for your suggestions. I am not losing the spikes now but one problem still lies, when the liquid stops flowing, the last reading is still being sent to ThingSpeak. I have made the changes according to your suggestions.
Can you tell me what else I need to change? Updated code is below:
#include "ThingSpeak.h"
//#define USE_WIFI101_SHIELD
#if defined(ARDUINO_AVR_YUN)
#include "YunClient.h"
YunClient client;
#else
#if defined(USE_WIFI101_SHIELD) || defined(ARDUINO_SAMD_MKR1000) || defined(ARDUINO_ARCH_ESP8266)
// Use WiFi
#ifdef ARDUINO_ARCH_ESP8266
#include <ESP8266WiFi.h>
#else
#include <SPI.h>
#include <WiFi101.h>
#endif
char ssid[] = "<>"; // your network SSID (name)
char pass[] = "<>"; // your network password
int status = WL_IDLE_STATUS;
WiFiClient client;
#elif defined(USE_ETHERNET_SHIELD)
// Use wired ethernet shield
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
EthernetClient client;
#endif
#endif
unsigned long myChannelNumber = ;
const char * myWriteAPIKey = "";
byte statusLed = 13;
byte sensorInterrupt = 0; // 0 = digital pin 2
byte sensorPin = 3;
// The hall-effect flow sensor outputs approximately 4.5 pulses per second per
// litre/minute of flow.
float calibrationFactor = 9.5;
volatile byte pulseCount;
float flowRate;
unsigned int flowMilliLitres;
int totalMilliLitres;
unsigned long oldTime;
void setup() {
#ifdef ARDUINO_AVR_YUN
Bridge.begin();
#else
#if defined(ARDUINO_ARCH_ESP8266) || defined(USE_WIFI101_SHIELD) || defined(ARDUINO_SAMD_MKR1000)
WiFi.begin(ssid, pass);
#else
Ethernet.begin(mac);
#endif
#endif
ThingSpeak.begin(client);
pinMode(statusLed, OUTPUT);
digitalWrite(statusLed, HIGH); // We have an active-low LED attached
pinMode(sensorPin, INPUT);
digitalWrite(sensorPin, HIGH);
pulseCount = 0;
flowRate = 0.0;
flowMilliLitres = 0;
totalMilliLitres = 0;
oldTime = 0;
// The Hall-effect sensor is connected to pin 2 which uses interrupt 0.
// Configured to trigger on a FALLING state change (transition from HIGH
// state to LOW state)
attachInterrupt(sensorInterrupt, pulseCounter, RISING);
}
void loop() {
if((millis() - oldTime) > 20000)
{
// Disable the interrupt while calculating flow rate and sending the value to
// the host
detachInterrupt(sensorInterrupt);
// Because this loop may not complete in exactly 1 second intervals we calculate
// the number of milliseconds that have passed since the last execution and use
// that to scale the output. We also apply the calibrationFactor to scale the output
// based on the number of pulses per second per units of measure (litres/minute in
// this case) coming from the sensor.
flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount) / calibrationFactor;
pulseCount=0;
// Note the time this processing pass was executed. Note that because we've
// disabled interrupts the millis() function won't actually be incrementing right
// at this point, but it will still return the value it was set to just before
// interrupts went away.
oldTime = millis();
// Divide the flow rate in litres/minute by 60 to determine how many litres have
// passed through the sensor in this 1 second interval, then multiply by 1000 to
// convert to millilitres.
flowMilliLitres = (flowRate / 60) * 1000;
// Add the millilitres passed in this second to the cumulative total
totalMilliLitres += flowMilliLitres;
unsigned int frac;
// Serial.print("Flow rate: ");
//Serial.print(int(flowRate)); // Print the integer part of the variable
//Serial.print("."); // Print the decimal point
// Determine the fractional part. The 10 multiplier gives us 1 decimal place.
frac = (flowRate - int(flowRate)) * 10;
ThingSpeak.writeField(myChannelNumber, 1, (long ) totalMilliLitres, myWriteAPIKey);
}
//unsigned long tl = totalMilliLitres;
}
void pulseCounter()
{
// Increment the pulse counter
pulseCount++;
}