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### Topic: 得到風速計的數據一直是0零 (Read 2143 times)previous topic - next topic

#### AmySakura

##### Feb 22, 2018, 12:21 pmLast Edit: Feb 22, 2018, 12:30 pm by AmySakura

Code: [Select]

/*  The SEN-08942 is an anemometer, wind vane and rain gauge set for prototyping an amateur
weather station.

SEN-08942:
http://www.sparkfun.com/products/8942
Spec http://www.sparkfun.com/datasheets/Sensors/Weather/Weather%20Sensor%20Assembly..pdf
http://www.sparkfun.com/products/8942
http://www.lextronic.fr/P4452-capteurs-pour-station-meteo.html
For its complement map SparkFun Weather Shield.
http://air.imag.fr/index.php/SparkFun_Weather_Shield
*/

/* Arduino sketch for Weather device from Sparkfun.
Uses only the wind direction vane and the anemometer (not the rain gauge).

Although the inclination for a weather logger is to run it for
a long time, due to the way Wiring.c implements the millis() function,
this should be restarted, oh, monthly. The millis() functions overflows
after about 49 days. We could allow for that here, and handle the
wraparound, but you've got bigger problems anyway with the delay()
function at an overflow, so it's best to "reboot".

=========================================================
ANEMOMETER
=========================================================
This is connected to Arduino ground on one side, and pin 2 (for the
attachInterrupt(0, ...) on the other.
Pin 2 is pulled up, and the reed switch on the anemometer will send
that to ground once per revolution, which will trigger the interrupt.
We count the number of revolutions in 5 seconds, and divide by 5.
1 Hz (rev/sec) = 1.492 mph = 2.40114125 kph = 2401.1 m/h

=========================================================
WIND DIRECTION VANE
=========================================================
We use a classic voltage divider to measure the resistance in
the weather vane, which varies by direction.
1023 * (R/(10000+R))
where R is the unknown resistance from the vane. We'll scale
the 1023 down to a 255 range, to match the datasheet docs.

+5V
|
<
>     10K
<   Resistor
<
>
|
Analog Pin 5------|
|
-----------| To weather vane
| (mystery resistance)
-----------|
|
|
-----
---
-
The ADC values we get for each direction (based on a 255 max)
follow, assuming that pointing away from the assembly center
is sector zero. The sector number is just which 45-degree sector
it is, clockwise from the "away" direction. The direction
shown is assuming that "away" is West. Depending how
you orient the system, you'll have to adjust the directions.

0        18        W
1        33        NW
2        57        N
7        97        SW
3       139        NE
6       183        S
5       208        SE
4       232        E

The values in the ADC table below list the midpoints between
these, so our reading can vary a bit. We'll pick the first value
=========================================================
RAIN GAUGE
=========================================================
Implemented here.
It is done the same way as the anemometer, and use
attachInterrupt(1, ...) on pin 3. Each interrupt represents
.011 inches of rain (0.2794 mm), according to the docs.
*********************************************************************/

#define PIN_ANEMOMETER  2     // Digital 2 for anemometer (wind speed)

/* How often we want to calculate wind speed or direction
每隔 5sec = 5000ms 紀錄風速數據 */
#define MSECS_CALC_WIND_SPEED 5000
/*================== Declare Variables ==========================*/
volatile int numRevsAnemometer;  // Incremented in the interrupt
// For interrupt use volatile to avoid failure
unsigned long nextCalcSpeed;     // 下一次計算平均風速的 時間點
unsigned long time;              // Millis() at each start of loop()

/*================== Declare Functions ==========================*/
void countAnemometer();
void calcWindSpeed();
/*================== Initialize =================================*/
void setup() {
Serial.begin(9600);
pinMode(PIN_ANEMOMETER, INPUT);
digitalWrite(PIN_ANEMOMETER, HIGH);
attachInterrupt(0, countAnemometer, FALLING);// Interrupt 0 在 pin 2 上
nextCalcSpeed = millis() + MSECS_CALC_WIND_SPEED;

delay(100);

Serial.println("Revolutions\t Wind speed (m/h)");
}

/*================== Main loop ==================================
* 間隔 MSECS_CALC_WIND_SPEED (5sec) 後，呼叫function: calcWindSpeed() 得到 風速數據
* 下一次取得 風速數據 的時間點: 再過 5sec 後
=================================================================*/
void loop() {
time = millis();
if (time >= nextCalcSpeed) {
calcWindSpeed();
nextCalcSpeed = time + MSECS_CALC_WIND_SPEED;
}
}

/*=============== countAnemometer() =============================
* Interrupt handler for anemometer. Called each time the reed
* switch triggers (one revolution).
=================================================================*/
void countAnemometer() {
numRevsAnemometer++;
}

/*=============== calcWindSpeed() ===============================
* Calculate the wind speed, and display it (or log it, whatever).
* 1 rev/sec = 1.492 mph = 2.40114125 kph = 2401.1 m/h
=================================================================*/
void calcWindSpeed() {
int x,r, iSpeed; // x = 整數，r = 小數
// This will produce: m/h * 10
// (didn't calc right when done as one statement)
long speed = 24011;
speed = speed*numRevsAnemometer/MSECS_CALC_WIND_SPEED;
iSpeed = speed;         // Need this for formatting below

x = iSpeed / 10;
r = iSpeed % 10;
Serial.print(numRevsAnemometer); Serial.print("\t\t "); Serial.print(x); Serial.print('.'); Serial.println(r);

numRevsAnemometer = 0;        // Reset counter
}

Code: [Select]

#define PIN_RAINGAUGE 3
#define MSECS_CALC_RAIN_FALL  5000         // 5sec
volatile int numDropsRainGauge = 0;
unsigned long nextCalcRain;
unsigned long time;
void setup() {
Serial.begin(9600);
attachInterrupt(digitalPinToInterrupt(PIN_RAINGAUGE), countRainGauge, FALLING);
nextCalcRain = millis() + MSECS_CALC_RAIN_FALL;
delay(100);
}

void loop() {
time = millis();
if(time >= nextCalcRain) {
calcRainFall();
nextCalcRain = time + MSECS_CALC_RAIN_FALL;
}
}

void countRainGauge(){
numDropsRainGauge++;
Serial.println(numDropsRainGauge);
}

void calcRainFall(){
float Rain = 0.279400;
Rain = Rain*numDropsRainGauge;
Rain = Rain/MSECS_CALC_RAIN_FALL*1000; //mm per sec

Serial.print("Rain fall(mm/sec):\t");Serial.println(Rain);
numDropsRainGauge = 0;
}

#### AmySakura

#1
##### Feb 22, 2018, 12:32 pm

How to Hookup Davis Anemometer to Arduino (Part 2 of 3)

Code: [Select]

#include <math.h>

#define WindSensorPin (2) // The pin location of the anemometer sensor

volatile unsigned long Rotations; // cup rotation counter used in interrupt routine
volatile unsigned long ContactBounceTime; // Timer to avoid contact bounce in interrupt routine
float WindSpeed; // speed miles per hour

void setup() {
Serial.begin(9600);
pinMode(WindSensorPin, INPUT);
attachInterrupt(digitalPinToInterrupt(WindSensorPin), isr_rotation, FALLING);

Serial.println("Davis Wind Speed Test");
Serial.println("Rotations\tMPH");
}

void loop() {
Rotations = 0;  // Set Rotations count to 0 ready for calculations
sei();          // Enables interrupts
delay (3000);   // Wait 3 seconds to average
cli();          // Disable interrupts
/* convert to mp/h using the formula V=P(2.25/T)
V = P(2.25/3) = P * 0.75 */

WindSpeed = Rotations * 0.75;
Serial.print(Rotations); Serial.print("\t\t");Serial.println(WindSpeed);
}

// This is the function that the interrupt calls to increment the rotation count
void isr_rotation () {
if ((millis() - ContactBounceTime) > 15 ) { // debounce the switch contact.
Rotations++;
ContactBounceTime = millis();
}
}

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