Led sensor - Revision history

FabienM: /* How does it work ? */

2008-09-25T19:33:00Z

How does it work ?

← Older revision		Revision as of 21:33, 25 September 2008
Line 2:		Line 2:

	To test this phenomena, I have used a pin of the FPGA, and design a little component/IP that provides the discharging time in a register.		To test this phenomena, I have used a pin of the FPGA, and design a little component/IP that provides the discharging time in a register.


	= How does it work ? =		= How does it work ? =
Line 23:		Line 24:

	When led is charged, fsm disconnect ''cathode'' and count until the ''value''		When led is charged, fsm disconnect ''cathode'' and count until the ''value''
	reach 0. The result of count is available on 16bits read register.		reach 0. The result of count is available on 16bits read register (named
			counter). Counter can be convert in time with formula :

			divisor x clock_period x counter = led_disharge_period

			By default, divisor is equal to 10. It's possible to change the divisor writing on the same register (named divisor).

	[[Image:ledtouchgraph.png\|500px\|center]]		[[Image:ledtouchgraph.png\|500px\|center]]

2008-09-25T19:32:30Z

Undo revision 4655 by FabienM (Talk)

@@ Line 1: / Line 1: @@
 = How does it work ? =
@@ Line 19: / Line 23: @@
 When led is charged, fsm disconnect ''cathode'' and count until the ''value''
-reach 0. The result of count is available on 16bits read register (named
+reach 0. The result of count is available on 16bits read register.
 [[Image:ledtouchgraph.png|500px|center]]

2008-09-25T19:29:04Z

@@ Line 1: / Line 1: @@
 = How does it work ? =
@@ Line 23: / Line 19: @@
 When led is charged, fsm disconnect ''cathode'' and count until the ''value''
-reach 0. The result of count is available on 16bits read register.
+reach 0. The result of count is available on 16bits read register (named
 [[Image:ledtouchgraph.png|500px|center]]

2008-09-25T19:22:24Z

How does it work ?

← Older revision		Revision as of 21:22, 25 September 2008
Line 7:		Line 7:
	Ledsensor ip formed by by four entities :		Ledsensor ip formed by by four entities :

	[[Image:structledtouch.png\|~~300px~~\|center]]		[[Image:structledtouch.png\|500px\|center]]


Line 18:		Line 18:

	[[Image:ledtouchschema.png\|300px\|center]]		[[Image:ledtouchschema.png\|300px\|center]]

			On read from ''wishbone16'', the '''fsm''' will reset the counter and load the
			led during a ''charge_period''.

			When led is charged, fsm disconnect ''cathode'' and count until the ''value''
			reach 0. The result of count is available on 16bits read register.



			[[Image:ledtouchgraph.png\|500px\|center]]

	= Code =		= Code =

2008-09-25T19:03:19Z

How does it work ?

← Older revision		Revision as of 21:03, 25 September 2008
Line 6:		Line 6:

	Ledsensor ip formed by by four entities :		Ledsensor ip formed by by four entities :

			[[Image:structledtouch.png\|300px\|center]]


	* '''cnt''' : like «counter» this entity provide counter to measure ledcapacitor discharge, it also provide charge period timing.		* '''cnt''' : like «counter» this entity provide counter to measure ledcapacitor discharge, it also provide charge period timing.
Line 11:		Line 14:
	* '''wbread''' : This entity is Wishbone 16-data bits bus manager.		* '''wbread''' : This entity is Wishbone 16-data bits bus manager.
	* '''fsm''' : This is the main component of the IP, this state machine drive the component. The working of the fsm is describe below :		* '''fsm''' : This is the main component of the IP, this state machine drive the component. The working of the fsm is describe below :



	[[Image:ledtouchschema.png\|300px\|center]]		[[Image:ledtouchschema.png\|300px\|center]]


	= Code =		= Code =

2008-09-24T20:55:32Z

← Older revision		Revision as of 22:55, 24 September 2008
Line 2:		Line 2:

	To test this phenomena, I have used a pin of the FPGA, and design a little component/IP that provides the discharging time in a register.		To test this phenomena, I have used a pin of the FPGA, and design a little component/IP that provides the discharging time in a register.

			= How does it work ? =

			Ledsensor ip formed by by four entities :

			* '''cnt''' : like «counter» this entity provide counter to measure ledcapacitor discharge, it also provide charge period timing.
			* '''led''' : This entity is used to drive the led. It has four signal, one to load capacitor «charge», one to read led value and two others to branch led (cathode and anode).
			* '''wbread''' : This entity is Wishbone 16-data bits bus manager.
			* '''fsm''' : This is the main component of the IP, this state machine drive the component. The working of the fsm is describe below :

			[[Image:ledtouchschema.png\|300px\|center]]


	= Code =		= Code =
Line 7:		Line 19:
	[http://fabienmarteau.free.fr/images/synthesis.tar.gz here]		[http://fabienmarteau.free.fr/images/synthesis.tar.gz here]

	~~= How does it work ? =~~
	~~[[Image:ledtouchschema.png\|300px\|center]]~~
	= Results =		= Results =

2008-08-24T18:26:52Z

← Older revision		Revision as of 20:26, 24 August 2008
Line 1:		Line 1:
	According to [http://www.merl.com/reports/docs/TR2003-35.pdf this] ~~paper~~, a simple ~~led~~ can be a light sensor if it used in reverse mode. In fact if ~~led~~ is used in invert, it ~~become~~ a variable capacitance.		According to [http://www.merl.com/reports/docs/TR2003-35.pdf this paper], a simple LED can be a light sensor if used in reverse mode. In fact if LED is used in invert, it becomes a variable capacitance.

			To test this phenomena, I have used a pin of the FPGA, and design a little component/IP that provides the discharging time in a register.
	To test this phenomena , I used to pin of the FPGA, and design a little component that ~~provide~~ the discharging time in a register.

	= Code =		= Code =
Line 8:		Line 7:
	[http://fabienmarteau.free.fr/images/synthesis.tar.gz here]		[http://fabienmarteau.free.fr/images/synthesis.tar.gz here]

	= How ~~that~~ work ? =		= How does it work ? =
	[[Image:ledtouchschema.png\|300px\|center]]		[[Image:ledtouchschema.png\|300px\|center]]
	= Results =		= Results =

	With a green standard led that ~~give~~ :		With a green standard led, that gives :

	[[Image:greenplot.png\|300px\|center]]		[[Image:greenplot.png\|300px\|center]]

2008-08-04T20:28:58Z

← Older revision		Revision as of 22:28, 4 August 2008
Line 3:		Line 3:

	To test this phenomena , I used to pin of the FPGA, and design a little component that provide the discharging time in a register.		To test this phenomena , I used to pin of the FPGA, and design a little component that provide the discharging time in a register.

			= Code =

			[http://fabienmarteau.free.fr/images/synthesis.tar.gz here]

	= How that work ? =		= How that work ? =

2008-08-03T19:31:35Z

← Older revision		Revision as of 21:31, 3 August 2008
Line 4:		Line 4:
	To test this phenomena , I used to pin of the FPGA, and design a little component that provide the discharging time in a register.		To test this phenomena , I used to pin of the FPGA, and design a little component that provide the discharging time in a register.

			= How that work ? =
			[[Image:ledtouchschema.png\|300px\|center]]
			= Results =

	[[Image:~~ledtouchschema~~.png\|300px\|center]]		With a green standard led that give :

			[[Image:greenplot.png\|300px\|center]]

2008-08-03T19:14:13Z

← Older revision		Revision as of 21:14, 3 August 2008
Line 4:		Line 4:
	To test this phenomena , I used to pin of the FPGA, and design a little component that provide the discharging time in a register.		To test this phenomena , I used to pin of the FPGA, and design a little component that provide the discharging time in a register.

	[[Image:ledtouchschema.png]]
			[[Image:ledtouchschema.png\|300px\|center]]