Digital Input Primer - Revision history

Burley: /* Digital Input Hardware Filter */

2014-04-25T13:54:41Z

Digital Input Hardware Filter

← Older revision		Revision as of 13:54, 25 April 2014
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	===Digital Input Hardware Filter===		===Digital Input Hardware Filter===
	There is built-in filtering on the digital input, to eliminate false triggering from electrical noise.		There is built-in filtering on the digital input, to eliminate false triggering from electrical noise.
	The digital input is first RC filtered by a 15K/100nF node, which will reject noise of higher frequency than ~~1Khz~~.		The digital input is first RC filtered by a 15K/100nF node, which will reject noise of higher frequency than 1kHz.
	This filter generally eliminates the need to shield the digital input from inductive and capacitive coupling likely to occur in wiring harnesses.		This filter generally eliminates the need to shield the digital input from inductive and capacitive coupling likely to occur in wiring harnesses.
	You can further reduce noise by externally filtering the input signal, but you will lose sensitivity in the process.		You can further reduce noise by externally filtering the input signal, but you will lose sensitivity in the process.

Burley: /* Introduction */

2013-10-10T17:56:36Z

Introduction

← Older revision		Revision as of 17:56, 10 October 2013
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	Digital inputs are one of the easiest components to work with, since all that is required is a simple check to see which state they are in when an event triggers.		Digital inputs are one of the easiest components to work with, since all that is required is a simple check to see which state they are in when an event triggers.

	'''Note:''' The digital inputs on the [[1012_User_Guide\|1012 - PhidgetInterfaceKit 0/16/16]] are active high rather than active low, so the instructions on this page do not apply. For information on the inputs on the 1012 please refer to the [[1012 User Guide#Digital Inputs\|technical section of it's User Guide].		'''Note:''' The digital inputs on the [[1012_User_Guide\|1012 - PhidgetInterfaceKit 0/16/16]] are active high rather than active low, so the instructions on this page do not apply. For information on the inputs on the 1012 please refer to the [[1012 User Guide#Digital Inputs\|technical section of it's User Guide]].

	==Specifications==		==Specifications==

Burley: /* Introduction */

2013-10-10T17:56:28Z

Introduction

← Older revision		Revision as of 17:56, 10 October 2013
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	Digital inputs are one of the easiest components to work with, since all that is required is a simple check to see which state they are in when an event triggers.		Digital inputs are one of the easiest components to work with, since all that is required is a simple check to see which state they are in when an event triggers.

	'''Note:''' The digital inputs on the [[1012_User_Guide\|1012 - PhidgetInterfaceKit 0/16/16]] are active high rather than active low, so the instructions on this page do not apply.		'''Note:''' The digital inputs on the [[1012_User_Guide\|1012 - PhidgetInterfaceKit 0/16/16]] are active high rather than active low, so the instructions on this page do not apply. For information on the inputs on the 1012 please refer to the [[1012 User Guide#Digital Inputs\|technical section of it's User Guide].

	==Specifications==		==Specifications==

Mparadis at 17:53, 4 October 2013

2013-10-04T17:53:16Z

← Older revision		Revision as of 17:53, 4 October 2013
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	Digital inputs are one of the easiest components to work with, since all that is required is a simple check to see which state they are in when an event triggers.		Digital inputs are one of the easiest components to work with, since all that is required is a simple check to see which state they are in when an event triggers.

			'''Note:''' The digital inputs on the [[1012_User_Guide\|1012 - PhidgetInterfaceKit 0/16/16]] are active high rather than active low, so the instructions on this page do not apply.

	==Specifications==		==Specifications==

Mparadis at 21:03, 27 July 2012

2012-07-27T21:03:31Z

← Older revision		Revision as of 21:03, 27 July 2012
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	If the resistance falls below 3.75k Ohms, the Digital Input will go TRUE.		If the resistance falls below 3.75k Ohms, the Digital Input will go TRUE.
	If the resistance rises above 75k Ohms, the Digital Input will go FALSE.		If the resistance rises above 75k Ohms, the Digital Input will go FALSE.

	~~<br clear="all">~~

	~~==Helpful Tips==~~
	~~===Update Rate===~~
	*125 samples/sec is for each individual channel, not split between all channels.
	*You can't "turn off" unused channels to improve update rate on the active channels.
	*This value is already close to the spec for our USB processor, so there isn't much room to tinker.

Mparadis: /* Electrical Specifications */

2012-07-27T20:55:55Z

Electrical Specifications

← Older revision		Revision as of 20:55, 27 July 2012
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	===Electrical Specifications===		===Electrical Specifications===

	[[Image:digital_input.jpg\|right\|300px\|link=\|thumb\|Schematic for a Phidgets digital input.~~<br/>[[Media:digital_input.jpg\|Full-sized Image]]~~]]		[[Image:digital_input.jpg\|right\|300px\|link=\|thumb\|Schematic for a Phidgets digital input.]]

	The digital inputs have a built in 15K pull-up resistor.		The digital inputs have a built in 15K pull-up resistor.

Mparadis: /* Using the Digital Inputs */

2012-07-27T20:55:45Z

Using the Digital Inputs

Mparadis: /* Electrical Specifications */

2012-07-27T20:54:13Z

Electrical Specifications

← Older revision		Revision as of 20:54, 27 July 2012
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	===Electrical Specifications===		===Electrical Specifications===

	[[Image:digital_input.jpg\|right\|thumb\|Schematic for a Phidgets digital input.]]		[[Image:digital_input.jpg\|right\|300px\|link=\|thumb\|Schematic for a Phidgets digital input.<br/>[[Media:digital_input.jpg\|Full-sized Image]]]]

	The digital inputs have a built in 15K pull-up resistor.		The digital inputs have a built in 15K pull-up resistor.

Cora: /* Specifications */

2012-06-29T15:24:38Z

Specifications

← Older revision		Revision as of 15:24, 29 June 2012
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	===Digital Input Hysteresis===		===Digital Input Hysteresis===
	The digital input has hysteresis - that is, it will hold ~~it’s~~ current state (false or true), unless a large change occurs.		The digital input has hysteresis - that is, it will hold its current state (false or true), unless a large change occurs.
	To guarantee FALSE, the digital input must be at least 3.75V, and to guarantee TRUE, the digital input must be less than 1.25V.		To guarantee FALSE, the digital input must be at least 3.75V, and to guarantee TRUE, the digital input must be less than 1.25V.

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

	==Using the Digital Inputs==		==Using the Digital Inputs==
	Here are some circuit diagrams that illustrate how to connect various devices to the digital inputs on your Phidget.		Here are some circuit diagrams that illustrate how to connect various devices to the digital inputs on your Phidget.

Cora: /* Helpful Tips */

2012-06-29T15:24:24Z

Helpful Tips

← Older revision		Revision as of 15:24, 29 June 2012
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	*125 samples/sec is for each individual channel, not split between all channels.		*125 samples/sec is for each individual channel, not split between all channels.
	*You can't "turn off" unused channels to improve update rate on the active channels.		*You can't "turn off" unused channels to improve update rate on the active channels.
	*This value is already close to the spec for our USB processor, so there isn't much room to tinker ~~with this spec~~.		*This value is already close to the spec for our USB processor, so there isn't much room to tinker.

← Older revision		Revision as of 20:55, 27 July 2012
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	===Wiring a switch to a Digital Input===		===Wiring a switch to a Digital Input===

	[[Image:switch_digital_input.jpg\|right\|thumb\|Schematic for connecting a switch to a digital input.]]		[[Image:switch_digital_input.jpg\|right\|300px\|link=\|thumb\|Schematic for connecting a switch to a digital input.]]

	Closing the switch causes the digital input to report TRUE.		Closing the switch causes the digital input to report TRUE.
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	===Monitoring the Position of a Relay===		===Monitoring the Position of a Relay===

	[[Image:relay_position.jpg\|right\|thumb\|Schematic for connecting to a relay.]]		[[Image:relay_position.jpg\|right\|300px\|link=\|thumb\|Schematic for connecting to a relay.]]

	The relay contact can be treated as a switch, and wired up similarly.		The relay contact can be treated as a switch, and wired up similarly.
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	===Detecting an External Voltage with an N-Channel MOSFET===		===Detecting an External Voltage with an N-Channel MOSFET===

	[[Image:external_voltage_mosfet.jpg\|right\|thumb\|Schematic for detecting voltage with a NMOS transistor.]]		[[Image:external_voltage_mosfet.jpg\|right\|300px\|link=\|thumb\|Schematic for detecting voltage with a NMOS transistor.]]

	A MOSFET can be used to detect the presence of an external voltage.		A MOSFET can be used to detect the presence of an external voltage.
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	===Isolating a Digital Input with an Optocoupler===		===Isolating a Digital Input with an Optocoupler===

	[[Image:isolating_digital_input_optocoupler.jpg\|right\|thumb\|Schematic showing isolation of a digital input with an optocoupler.]]		[[Image:isolating_digital_input_optocoupler.jpg\|right\|300px\|link=\|thumb\|Schematic showing isolation of a digital input with an optocoupler.]]

	When driving current through the LED, the Digital Input will report TRUE.		When driving current through the LED, the Digital Input will report TRUE.
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	===Detecting an External Voltage with an NPN Transistor===		===Detecting an External Voltage with an NPN Transistor===

	[[Image:external_voltage_npn.jpg\|right\|thumb\|Schematic for detecting voltage with an NPN transistor.]]		[[Image:external_voltage_npn.jpg\|right\|thumb\|300px\|link=\|Schematic for detecting voltage with an NPN transistor.]]

	This circuit can be used to measure if a battery is connected, or if 12V (for example) is on a wire.		This circuit can be used to measure if a battery is connected, or if 12V (for example) is on a wire.
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	===Using a Capacitive or Inductive Proximity Switch===		===Using a Capacitive or Inductive Proximity Switch===

	[[Image:proximity_switch.jpg\|right\|thumb\|Schematic for connecting to a proximity switch.]]		[[Image:proximity_switch.jpg\|right\|thumb\|300px\|link=\|Schematic for connecting to a proximity switch.]]

	Capacitive proximity switches can detect the presence of nearby non-metallic objects, whereas inductive proximity switches can detect only the presence of metallic objects.		Capacitive proximity switches can detect the presence of nearby non-metallic objects, whereas inductive proximity switches can detect only the presence of metallic objects.
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	===Using an FSR or Variable Resistor as a Switch===		===Using an FSR or Variable Resistor as a Switch===

	[[Image:fsr_switch.jpg\|right\|thumb\|Schematic for using an FSR as a switch.]]		[[Image:fsr_switch.jpg\|right\|thumb\|300px\|link=\|Schematic for using an FSR as a switch.]]

	The digital inputs can be easily wired to use many variable resistors as switches.		The digital inputs can be easily wired to use many variable resistors as switches.