Water flow sensor and plot.ly

So i have been trying for some time to get my water flow sensor to work with plot.ly. They have the code in their website, but it seems that arduino reads only the rising sensor values, not the falling ones. I tried to modify their code but with no success. I suspect that the problem lies in the part

if (x == HIGH) {
//low to high transition!
pulses++;

since it is not followed by a condition for the falling values, but no matter what i tried, i could not manage to make this thing work.

Do you guys have any ideas ?

Here is the complete code:

#include <SPI.h>
#include <Ethernet.h>
#include “plotly_streaming_ethernet.h”

#define flow_sensor_pin 2

// Sign up to plotly here: https://plot.ly
// View your API key and streamtokens here: https://plot.ly/settings
#define nTraces 1
// View your tokens here: https://plot.ly/settings
// Supply as many tokens as data traces
// e.g. if you want to ploty A0 and A1 vs time, supply two tokens
char *tokens[nTraces] = {“25tm9197rz”};
// arguments: username, api key, streaming token, filename
plotly graph(“workshop”, “v6w5xlbx9j”, tokens, “filename”, nTraces);

// count how many pulses!
volatile uint16_t pulses = 0;
// track the state of the pulse pin
volatile uint8_t lastflowpinstate;
// you can try to keep time of how long it is between pulses
volatile uint32_t lastflowratetimer = 0;
// and use that to calculate a flow rate
volatile float flowrate;
// Interrupt is called once a millisecond, looks for any pulses from the sensor!
SIGNAL(TIMER0_COMPA_vect) {
uint8_t x = digitalRead(FLOWSENSORPIN);

if (x == lastflowpinstate) {
lastflowratetimer++;
return; // nothing changed!
}

if (x == HIGH) {
//low to high transition!
pulses++;
}
lastflowpinstate = x;
flowrate = 1000.0;
flowrate /= lastflowratetimer; // in hertz
lastflowratetimer = 0;
}

void useInterrupt(boolean v) {
if (v) {
// Timer0 is already used for millis() - we’ll just interrupt somewhere
// in the middle and call the “Compare A” function above
OCR0A = 0xAF;
TIMSK0 |= _BV(OCIE0A);
} else {
// do not call the interrupt function COMPA anymore
TIMSK0 &= ~_BV(OCIE0A);
}
}

byte mac = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte my_ip = { 199, 168, 222, 18 }; // google will tell you: “public ip address”

void startEthernet(){
Serial.println("… Initializing ethernet");
if(Ethernet.begin(mac) == 0){
Serial.println("… Failed to configure Ethernet using DHCP");
// no point in carrying on, so do nothing forevermore:
// try to congifure using IP address instead of DHCP:
Ethernet.begin(mac, my_ip);
}
Serial.println("… Done initializing ethernet");
delay(1000);
}

void setup() {
graph.maxpoints = 100;
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}

startEthernet();

bool success;
success = graph.init();
pinMode(flow_sensor_pin, INPUT);
digitalWrite(flow_sensor_pin, HIGH);
lastflowpinstate = digitalRead(flow_sensor_pin);
useInterrupt(true);
if(!success){while(true){}}
graph.openStream();
}

void loop() {
Serial.print("Freq: "); Serial.println(flowrate);
Serial.print(“Pulses: “); Serial.println(pulses, DEC);
float liters = pulses;
liters /= 7.5;
liters /= 60.0;
/*
// if a brass sensor use the following calculation
float liters = pulses;
liters /= 8.1;
liters -= 6;
liters /= 60.0;
*/
Serial.print(liters); Serial.println(” Liters”);
graph.plot(millis(), liters, tokens[0]);
delay(100);
}

which sensor did you use?

this one:

http://www.adafruit.com/product/828