Example Writeup: Analog Input - Revision history

Lynch: /* Circuit */

2008-01-26T18:08:33Z

Circuit

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	'''Editor's Note: This example "Circuit" section contains multiple examples, each its own subsection. Yours need not. Images should be small. In cases where a large image is necessary to get sufficient detail, display the image as a smaller thumbnail, and when the reader clicks on it, they can see a larger version, as with the image to the right.'''		'''Editor's Note: This example "Circuit" section contains multiple examples, each its own subsection. Yours need not. Images should be small. In cases where a large image is necessary to get sufficient detail, display the image as a smaller thumbnail, and when the reader clicks on it, they can see a larger version, as with the image to the right.'''

			'''This example circuit section does not include any photos. This is fine if everything is perfectly clear from your circuit diagram. In many cases, however, it is helpful to see a photo of a neatly wired circuit, showing the connections from the PIC to the device. In summary, it is OK to have only circuit diagrams if they are clear, it is ''not'' OK to have only a photo, and it is often best to have both a circuit diagram and a photo. Do not use unnecessarily memory-hogging photos; just use the minimum resolution necessary to be clear.'''

	'''Actual "Circuit" section begins below. Note the use of <nowiki><br clear=all></nowiki> statements to make sure descriptions line up with their associated images.'''		'''Actual "Circuit" section begins below. Note the use of <nowiki><br clear=all></nowiki> statements to make sure descriptions line up with their associated images.'''

Lynch: /* Code */

2008-01-26T18:05:16Z

Code

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	== Code ==		== Code ==

	'''You can include code as shown below. I find that the code has to be indented at least one space to prevent wiki interpretation of the pound sign # at the beginning of a line.'''		'''You can include code as shown below. I find that the code has to be indented at least one space to prevent wiki interpretation of the pound sign # at the beginning of a line, and other unexpected behavior.'''

	/*		/*

Lynch: /* Code */

2008-01-26T18:04:39Z

Code

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	'''You can include code as shown below. I find that the code has to be indented at least one space to prevent wiki interpretation of the pound sign # at the beginning of a line.'''		'''You can include code as shown below. I find that the code has to be indented at least one space to prevent wiki interpretation of the pound sign # at the beginning of a line.'''

	<code>
	/*		/*
	AnalogInput.c m.peshkin 2007-12-24		AnalogInput.c m.peshkin 2007-12-24
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	}		}
	}		}
	</code>

Lynch: /* Code */

2008-01-26T18:04:15Z

Code

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	*/		*/

	#include <18f4520.h>		#include <18f4520.h>
	#DEVICE ADC=10 // set ADC to 10 bit accuracy, or it could be just 8		#DEVICE ADC=10 // set ADC to 10 bit accuracy, or it could be just 8
	#fuses HS,NOLVP,NOWDT,NOPROTECT		#fuses HS,NOLVP,NOWDT,NOPROTECT

Lynch: /* Code */

2008-01-26T18:04:05Z

Code

← Older revision		Revision as of 13:04, 26 January 2008
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	*/		*/

	#include <18f4520.h>		#include <18f4520.h>
	#DEVICE ADC=10 // set ADC to 10 bit accuracy, or it could be just 8		#DEVICE ADC=10 // set ADC to 10 bit accuracy, or it could be just 8
	#fuses HS,NOLVP,NOWDT,NOPROTECT		#fuses HS,NOLVP,NOWDT,NOPROTECT

Lynch: /* Code */

2008-01-26T18:03:44Z

Code

← Older revision		Revision as of 13:03, 26 January 2008
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	== Code ==		== Code ==

			'''You can include code as shown below. I find that the code has to be indented at least one space to prevent wiki interpretation of the pound sign # at the beginning of a line.'''

	<code>		<code>

Lynch: /* Amplification and level shifting */

2008-01-26T18:01:59Z

Amplification and level shifting

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	The above circuit used a sensor without amplification, and the output voltage range was intrinsically limited to 0-5V by the supply rails of the circuit. If you wish to use an opamp or instrumentation amp to produce the voltage to be digitized, you will need to limit it to the 0-5V range, and possibly also to level-shift it so that both polarities of sensing are readable. There are many ways to accomplish these things.		The above circuit used a sensor without amplification, and the output voltage range was intrinsically limited to 0-5V by the supply rails of the circuit. If you wish to use an opamp or instrumentation amp to produce the voltage to be digitized, you will need to limit it to the 0-5V range, and possibly also to level-shift it so that both polarities of sensing are readable. There are many ways to accomplish these things.

	The best way is to use a level of 2.5V as your "null" level. If you use a rail-to-rail opamp with supply rails of 0 and 5V, its output is naturally limited to the PIC's analog input range.		The best way is to use a level of 2.5V as your "null" level. If you use a rail-to-rail opamp (for example, see the circuits below) with supply rails of 0 and 5V, its output is naturally limited to the PIC's analog input range.

	<br clear=all>		<br clear=all>

Lynch: /* Circuit */

2008-01-26T18:00:42Z

Circuit

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	A typical circuit for reading light intensity with a phototransistor is shown at right. Greater light level causes a lower voltage at pin AN0, and a lower value read by the PIC's ADC.		A typical circuit for reading light intensity with a phototransistor is shown at right. Greater light level causes a lower voltage at pin AN0, and a lower value read by the PIC's ADC.

			<br clear=all>
⚫	~~<b>~~Amplification and level shifting~~</b>~~

		⚫	=== Amplification and level shifting ===

	The above circuit used a sensor without amplification, and the output voltage range was intrinsically limited to 0-5V by the supply rails of the circuit. If you wish to use an opamp or instrumentation amp to produce the voltage to be digitized, you will need to limit it to the 0-5V range, and possibly also to level-shift it so that both polarities of sensing are readable. There are many ways to accomplish these things.		The above circuit used a sensor without amplification, and the output voltage range was intrinsically limited to 0-5V by the supply rails of the circuit. If you wish to use an opamp or instrumentation amp to produce the voltage to be digitized, you will need to limit it to the 0-5V range, and possibly also to level-shift it so that both polarities of sensing are readable. There are many ways to accomplish these things.

Lynch: /* Circuit */

2008-01-26T17:59:50Z

Circuit

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	[[image:All-actuators-captions-small.jpg\|thumb\|300px\|[[Actuators Available in the Mechatronics Lab\|Available Actuators]]\|right]]		[[image:All-actuators-captions-small.jpg\|thumb\|300px\|[[Actuators Available in the Mechatronics Lab\|Available Actuators]]\|right]]

	'''Editor's Note: This example "Circuit" section contains multiple examples, each its own subsection. Yours need not. Images should be small. In cases where a large image is necessary to get sufficient detail, display the image as a smaller thumbnail, and when the reader clicks on it, they can see a larger version, as with the image to the right.		'''Editor's Note: This example "Circuit" section contains multiple examples, each its own subsection. Yours need not. Images should be small. In cases where a large image is necessary to get sufficient detail, display the image as a smaller thumbnail, and when the reader clicks on it, they can see a larger version, as with the image to the right.'''

	Actual "Circuit" section begins below. Note the use of <nowiki><br clear=all></nowiki> statements to make sure descriptions line up with their associated images.'''		'''Actual "Circuit" section begins below. Note the use of <nowiki><br clear=all></nowiki> statements to make sure descriptions line up with their associated images.'''

	<br clear=all>		<br clear=all>

Lynch: /* Circuit */

2008-01-26T17:59:35Z

Circuit

← Older revision		Revision as of 12:59, 26 January 2008
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	'''Editor's Note: This example "Circuit" section contains multiple examples, each its own subsection. Yours need not. Images should be small. In cases where a large image is necessary to get sufficient detail, display the image as a smaller thumbnail, and when the reader clicks on it, they can see a larger version, as with the image to the right.		'''Editor's Note: This example "Circuit" section contains multiple examples, each its own subsection. Yours need not. Images should be small. In cases where a large image is necessary to get sufficient detail, display the image as a smaller thumbnail, and when the reader clicks on it, they can see a larger version, as with the image to the right.

	Actual "Circuit" section begins below. Note the use of <nowiki><br clear=all></nowiki> statements to make sure descriptions line up with their associated images.		Actual "Circuit" section begins below. Note the use of <nowiki><br clear=all></nowiki> statements to make sure descriptions line up with their associated images.'''

	<br clear=all>		<br clear=all>