Photo Cell Sensor - Revision history

Yajuan.dai: /* */

2014-08-19T10:08:00Z

‎

Yajuan.dai: /* Adjustable coupling */

2014-08-19T10:07:32Z

‎Adjustable coupling

Yajuan.dai: /* Introduction */

2014-08-19T10:07:00Z

‎Introduction

Katherine.d: /* Testing a Photocell */

2012-12-13T08:46:59Z

‎Testing a Photocell

Katherine.d at 08:42, 13 December 2012

2012-12-13T08:42:26Z

Katherine.d: /* Resource */

2012-12-13T08:15:43Z

‎Resource

Katherine.d: /* Resource */

2012-12-13T08:11:52Z

‎Resource

Katherine.d at 08:10, 13 December 2012

2012-12-13T08:10:27Z

Katherine.d: /* Using a Photocell */

2012-12-13T08:01:50Z

‎Using a Photocell

Katherine.d: /* Using a Photocell */

2012-12-13T07:59:23Z

‎Using a Photocell

← Older revision		Revision as of 10:08, 19 August 2014
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−	=== ===	+	== ==
	For most light-sentsitive applications like "is it light or dark out", "is there something in front of the sensor (that would block light)", "is there something interrupting a laser beam" (break-beam sensors), or "which of multiple sensors has the most light hitting it", photocells can be a good choice!		For most light-sentsitive applications like "is it light or dark out", "is there something in front of the sensor (that would block light)", "is there something interrupting a laser beam" (break-beam sensors), or "which of multiple sensors has the most light hitting it", photocells can be a good choice!

← Older revision		Revision as of 10:07, 19 August 2014
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	**[http://linksprite.com/wiki/index.php5?title=Sensors_Pack_for_Arduino Sensors Pack for Arduino] [KIT_SENPACK]		**[http://linksprite.com/wiki/index.php5?title=Sensors_Pack_for_Arduino Sensors Pack for Arduino] [KIT_SENPACK]

		+
		+	=== ===
	For most light-sentsitive applications like "is it light or dark out", "is there something in front of the sensor (that would block light)", "is there something interrupting a laser beam" (break-beam sensors), or "which of multiple sensors has the most light hitting it", photocells can be a good choice!		For most light-sentsitive applications like "is it light or dark out", "is there something in front of the sensor (that would block light)", "is there something interrupting a laser beam" (break-beam sensors), or "which of multiple sensors has the most light hitting it", photocells can be a good choice!

← Older revision		Revision as of 10:07, 19 August 2014
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	[[File:photocell.jpg \| 400px]]		[[File:photocell.jpg \| 400px]]
		+
		+	===Adjustable coupling===
		+	**[http://linksprite.com/wiki/index.php5?title=Sensors_Pack_for_Arduino Sensors Pack for Arduino] [KIT_SENPACK]

	For most light-sentsitive applications like "is it light or dark out", "is there something in front of the sensor (that would block light)", "is there something interrupting a laser beam" (break-beam sensors), or "which of multiple sensors has the most light hitting it", photocells can be a good choice!		For most light-sentsitive applications like "is it light or dark out", "is there something in front of the sensor (that would block light)", "is there something interrupting a laser beam" (break-beam sensors), or "which of multiple sensors has the most light hitting it", photocells can be a good choice!

@@ Line 42: / Line 42: @@
 The easiest way to determine how your photocell works is to connect a multimeter in resistance-measurement mode to the two leads and see how the resistance changes when shading the sensor with your hand, turning off lights, etc. Because the resistance changes a lot, an auto-ranging meter works well here. Otherwise, just make sure you try different ranges, between 1MΩ and 1KΩ before 'giving up'.
-[[File:testing1.jpg]]
+[[File:testing1.jpg | 400px]]
-[[File:testing2.jpg]]
+[[File:testing2.jpg | 400px]]
 === Connecting a Photocell ===

← Older revision		Revision as of 08:42, 13 December 2012
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	== Usage ==		== Usage ==
		+
		+	=== Testing a Photocell ===
		+
		+	The easiest way to determine how your photocell works is to connect a multimeter in resistance-measurement mode to the two leads and see how the resistance changes when shading the sensor with your hand, turning off lights, etc. Because the resistance changes a lot, an auto-ranging meter works well here. Otherwise, just make sure you try different ranges, between 1MΩ and 1KΩ before 'giving up'.
		+
		+	[[File:testing1.jpg]]
		+
		+	[[File:testing2.jpg]]

	=== Connecting a Photocell ===		=== Connecting a Photocell ===

@@ Line 351: / Line 351: @@
 == Resource ==
 *[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/PDV-P8001_datasheet.pdf Datasheet of PDV-P8001]
-*[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/DTS_A9950_A7060_B9060.pdf Datasheet]
+*[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/DTS_A9950_A7060_B9060.pdf Datasheet of A9950,A7060,B9060]
 *[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/DTS_A9950_A7060_B9060.pdf application notes on using]
 *[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/gde_photocellselecting.pdf selecting photocells]

← Older revision		Revision as of 08:10, 13 December 2012
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	[[File:srctimeout.gif]]		[[File:srctimeout.gif]]
		+
		+	== Resource ==
		+	*[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/PDV-P8001_datasheet.pdf Datasheet]
		+	*[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/DTS_A9950_A7060_B9060.pdf Datasheet]
		+	*[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/DTS_A9950_A7060_B9060.pdf application notes on using]
		+	*[https://s3.amazonaws.com/linksprite/Arduino_kits/SensorsPack/photo_cell/gde_photocellselecting.pdf selecting photocells]

← Older revision		Revision as of 08:01, 13 December 2012
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	[[File:rcschm.gif]]		[[File:rcschm.gif]]
		+
		+	In this case, our 'bucket' is a 0.1uF ceramic capacitor. You can change the capacitor nearly any way you want but the timing values will also change. 0.1uF seems to be an OK place to start for these photocells. If you want to measure brighter ranges, use a 1uF capacitor. If you want to measure darker ranges, go down to 0.01uF
		+
		+	<syntaxhighlight lang="c">
		+
		+	/* Photocell simple testing sketch.
		+	Connect one end of photocell to power, the other end to pin 2.
		+	Then connect one end of a 0.1uF capacitor from pin 2 to ground
		+	For more information see http://learn.adafruit.com/photocells */
		+
		+	int photocellPin = 2; // the LDR and cap are connected to pin2
		+	int photocellReading; // the digital reading
		+	int ledPin = 13; // you can just use the 'built in' LED
		+
		+	void setup(void) {
		+	// We'll send debugging information via the Serial monitor
		+	Serial.begin(9600);
		+	pinMode(ledPin, OUTPUT); // have an LED for output
		+	}
		+
		+	void loop(void) {
		+	// read the resistor using the RCtime technique
		+	photocellReading = RCtime(photocellPin);
		+
		+	if (photocellReading == 30000) {
		+	// if we got 30000 that means we 'timed out'
		+	Serial.println("Nothing connected!");
		+	} else {
		+	Serial.print("RCtime reading = ");
		+	Serial.println(photocellReading); // the raw analog reading
		+
		+	// The brighter it is, the faster it blinks!
		+	digitalWrite(ledPin, HIGH);
		+	delay(photocellReading);
		+	digitalWrite(ledPin, LOW);
		+	delay(photocellReading);
		+	}
		+	delay(100);
		+	}
		+
		+	// Uses a digital pin to measure a resistor (like an FSR or photocell!)
		+	// We do this by having the resistor feed current into a capacitor and
		+	// counting how long it takes to get to Vcc/2 (for most arduinos, thats 2.5V)
		+	int RCtime(int RCpin) {
		+	int reading = 0; // start with 0
		+
		+	// set the pin to an output and pull to LOW (ground)
		+	pinMode(RCpin, OUTPUT);
		+	digitalWrite(RCpin, LOW);
		+
		+	// Now set the pin to an input and...
		+	pinMode(RCpin, INPUT);
		+	while (digitalRead(RCpin) == LOW) { // count how long it takes to rise up to HIGH
		+	reading++; // increment to keep track of time
		+
		+	if (reading == 30000) {
		+	// if we got this far, the resistance is so high
		+	// its likely that nothing is connected!
		+	break; // leave the loop
		+	}
		+	}
		+	// OK either we maxed out at 30000 or hopefully got a reading, return the count
		+
		+	return reading;
		+	}
		+
		+	</syntaxhighlight>
		+
		+	[[File:srctimeout.gif]]

← Older revision		Revision as of 07:59, 13 December 2012
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	[[File:rctimediag.gif \| 400px]]		[[File:rctimediag.gif \| 400px]]

−	[[File:rcschm.gif ~~\| 400px~~]]	+	[[File:rcschm.gif]]