# Solved is a LED may flash according to a byte sent over a serial P.

February 28, 2013 at 05:55:31
Specs: Windows 7
 if we use a high definition camera in a very slow-motion mode. Could we see this led change? Or is the byte is too fast for the led lighting. Or maybe the led will take the average voltage?

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February 28, 2013 at 10:20:35
 LED light in nano seconds. The LED in your display are changing at up to 60 times a second and could go fasterThe faster the frame rate on the camera the better chance you have of seeing the LED flash. You could use the frame rate of the camera to work out exactly how fast the LED is flashingStuart

#1
February 28, 2013 at 07:14:58
 Do you mean a high speed camera that takes hundreds of frames a second instead off the normal 25-30 frames per secondIn that case you just set the baud rate of half the frame rate and you will see the LED flashing when it is played back a normal speed.Stuart

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#2
February 28, 2013 at 08:54:55
 Thank you for your very quick response StuartS! =)But I would like to know if the LED could light up this speed?

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#3
February 28, 2013 at 09:54:50
 It would depend on several factors such as the frames per second of your hi def camera, the speed of each frame, the off time between each frame on the camera, the baud rate of the serial port and the pulse width of the signal. It would also depend on how fast the LED responds. Too many factors involved to give you a definitive answer. If you need to measure a pulse on a serial port, your best bet would be to use an oscilloscope, preferably one with a sample and hold feature that would hold the voltage peak.

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Related Solutions

#4
February 28, 2013 at 10:20:35
 LED light in nano seconds. The LED in your display are changing at up to 60 times a second and could go fasterThe faster the frame rate on the camera the better chance you have of seeing the LED flash. You could use the frame rate of the camera to work out exactly how fast the LED is flashingStuart

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#5
February 28, 2013 at 12:59:18
 A serial port is capable of sending out over a hundred thousand pulses per second, there is no way he is going to be able to count how fast the LED is flashing at that rate. Even a professional high speed camera can't keep up with that.Something else to factor in is the current draw of the LED. I don't know what sort of current the serial port is capable of, but some LED's can draw a significant amount of power, possibly more than the serial port can output.

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#6
February 28, 2013 at 14:36:02
 Even a professional high speed camera can't keep up with that. A professional high speed camera can do millions of frames per second and they are even working on frame rates running into billions.With modern super sensitive CCDs such high frame rates are possible. It would not be possible with a conventional film camera.I wouldn't worry too much about current. In fact you may need some current limiting resistors to avoid blowing the LED;sWhen RS232 was common I had a LED tester witch plugged itnto the RS232 port in series with the cable. The LEDs flashed in accordance with the control and data signal passing through the connector, Red for Low. Green for High It had no adverse effect on the normal operation of the connection.Stuart

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#7
February 28, 2013 at 14:57:13
 I stand corrected.

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#8
March 1, 2013 at 12:50:59
 Thank you both for your very fast answers, you have answered all the questions I had.In truth, the purpose of this question was to produce a witness of data on a serial port. (LED). I think a pin of serial port can give something like 14mA.But the data are really too fast to be visible to the naked eye. Then I even wondered if the LED lights at this speed. (9600 baud) over coaxial cable.Based on your answers, the LED can light at very high speeds.

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