77 lines
2.1 KiB
C++
77 lines
2.1 KiB
C++
/*
|
|
Calibration
|
|
|
|
Demonstrates one techinque for calibrating sensor input. The sensor
|
|
readings during the first five seconds of the sketch execution
|
|
define the minimum and maximum of expected values attached to the
|
|
sensor pin.
|
|
|
|
The sensor minumum and maximum initial values may seem backwards.
|
|
Initially, you set the minimum high and listen for anything lower,
|
|
saving it as the new minumum. Likewise, you set the maximum low and
|
|
listen for anything higher as the new maximum.
|
|
|
|
The circuit:
|
|
* Analog sensor (potentiometer will do) attached to analog input 15
|
|
|
|
created 29 Oct 2008
|
|
By David A Mellis
|
|
Modified 17 Jun 2009
|
|
By Tom Igoe
|
|
|
|
http://arduino.cc/en/Tutorial/Calibration
|
|
|
|
Ported to Maple 27 May 2010
|
|
by Bryan Newbold
|
|
*/
|
|
|
|
// Constant (won't change):
|
|
const int sensorPin = 15; // pin that the sensor is attached to
|
|
|
|
// Variables:
|
|
int sensorMin = 1023; // minimum sensor value
|
|
int sensorMax = 0; // maximum sensor value
|
|
int sensorValue = 0; // the sensor value
|
|
|
|
void setup() {
|
|
// Declare the sensorPin as INPUT_ANALOG:
|
|
pinMode(sensorPin, INPUT_ANALOG);
|
|
|
|
// Turn on the built-in LED to signal the start of the calibration
|
|
// period:
|
|
pinMode(33, OUTPUT);
|
|
digitalWrite(33, HIGH);
|
|
|
|
// Calibrate during the first five seconds:
|
|
while (millis() < 5000) {
|
|
sensorValue = analogRead(sensorPin);
|
|
|
|
// Record the maximum sensor value:
|
|
if (sensorValue > sensorMax) {
|
|
sensorMax = sensorValue;
|
|
}
|
|
|
|
// Record the minimum sensor value:
|
|
if (sensorValue < sensorMin) {
|
|
sensorMin = sensorValue;
|
|
}
|
|
}
|
|
|
|
// Signal the end of the calibration period:
|
|
digitalWrite(33, LOW);
|
|
}
|
|
|
|
void loop() {
|
|
// Read the sensor:
|
|
sensorValue = analogRead(sensorPin);
|
|
|
|
// Apply the calibration to the sensor reading:
|
|
sensorValue = map(sensorValue, sensorMin, sensorMax, 0, 65535);
|
|
|
|
// In case the sensor value is outside the range seen during calibration:
|
|
sensorValue = constrain(sensorValue, 0, 65535);
|
|
|
|
// Fade the LED using the calibrated value:
|
|
pwmWrite(33, sensorValue);
|
|
}
|