You are not logged in.

#1 2005-11-17 21:17:05

kleptophobiac
Member
From: Sunnyvale, CA
Registered: 2004-04-25
Posts: 481

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.

Offline

#2 2005-11-17 23:37:49

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

Offline

#3 2005-11-18 00:07:10

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)

Offline

#4 2005-11-18 00:26:45

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.. roll

Offline

#5 2005-11-18 04:29:57

iBertus
Member
From: Greenville, NC
Registered: 2004-11-04
Posts: 2,228

Re: Real time blinking light

Nice ASCII art phrak!

Offline

#6 2005-11-18 08:32:03

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!!


·¬»· i am shadowhand, powered by webfaction

Offline

#7 2005-11-18 16:13:05

phrakture
Arch Overlord
From: behind you
Registered: 2003-10-29
Posts: 7,879
Website

Re: Real time blinking light

shadowhand wrote:

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

Offline

#8 2005-11-18 17:16:48

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

Offline

#9 2005-11-18 17:34:43

phrakture
Arch Overlord
From: behind you
Registered: 2003-10-29
Posts: 7,879
Website

Re: Real time blinking light

Oh oh oh! Theory time:

LM555Basics.GIF

Offline

Board footer

Powered by FluxBB