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kleptophobiac

Member

From: Sunnyvale, CA

Registered: 2004-04-25

Posts: 488

Real time blinking light

I need to be able to calibrate a camera's reported framerate against a known framerate. I'm using java to strobe a parallel port to blink an LED in front of the camera's lens. I'm using timers and actionevents to try and make a blinking light with a one second frequency.

Unfortunately, my one second is blatantly incorrect.

Is there a better (software) way to do this? I'm considering just making a piece of hardware to do the job, but that's messy.

Dusty

Schwag Merchant

From: Medicine Hat, Alberta, Canada

Registered: 2004-01-18

Posts: 5,986

Website

Re: Real time blinking light

Timers aren't terrbly accurate. I'm not sure what is accurate in Java (I *think* you can get realtime rates with it, but not sure how). You may be better off using C. (Did I just recommend something other than python?????)

Dusty

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phrakture

Arch Overlord

From: behind you

Registered: 2003-10-29

Posts: 7,879

Website

Re: Real time blinking light

You could do it with about $3 and a soldering iron

That is:
a 555 timer chip
1 Mohm resistor
100 ohm resistor
0.1 uF capacitor
9 volt battery, or 5-9 volt outlet transformer (old cell phone?)

1M resistor * 1uF capacitor will give you a period of 1second

I'll try this in ascii art:

+-----++++++[PWR]-------------+
|                             |
+--[1M R]-+--+---+--[1uF C]---+
|         |  |   |            |
|  _______|__|___|__________  |
+-[/RST   D  Thr Trg       ]  |
| [                        ]  |
| [     555 timer       Gnd]--+-------------+
| [                        ]                |
+-[Vcc                  Out]--[LED]--[100 R]+

CLR pin Not Connected (NC)

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medicated

Member

From: Storm Lake, IA

Registered: 2005-03-11

Posts: 79

Re: Real time blinking light

Yah..I was just about to say that.  You totally beat me to the punch..

iBertus

Member

From: Greenville, NC

Registered: 2004-11-04

Posts: 2,228

Re: Real time blinking light

Nice ASCII art phrak!

shadowhand

Member

From: MN, USA

Registered: 2004-02-19

Posts: 1,142

Website

Re: Real time blinking light

This has GOT to be the nerdiest thread I've seen in a while. 8) Cheers!!

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phrakture

Arch Overlord

From: behind you

Registered: 2003-10-29

Posts: 7,879

Website

Re: Real time blinking light

This has GOT to be the nerdiest thread I've seen in a while. 8) Cheers!!

Bah, that's like Freshman Electrical Engineer stuff - if you like I can throw in some VHDL for the same thing and give you a good source for an FPGA so you can upload the logic there (of course, the pin-outs would have to be modified based on the board).

Would you like VHDL for a router? I have that floating around somewhere too - oh and VHDL for an N-bit RISC processor (w/o FPU)...

/me nerds all over you

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http://phraktured.net

Dusty

Schwag Merchant

From: Medicine Hat, Alberta, Canada

Registered: 2004-01-18

Posts: 5,986

Website

Re: Real time blinking light

I want a router in ASCII!!

Dusty

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** Arch Linux Apparel and more ** Arch Linux stickers, laptop bags, jewelery ** I wrote a book on Python 3 ** and one on mental health **

phrakture

Arch Overlord

From: behind you

Registered: 2003-10-29

Posts: 7,879

Website

Re: Real time blinking light

Oh oh oh! Theory time:

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