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Topic: 3216 LED matrix refresh rate (Read 2466 times) previous topic - next topic

wexler

Hello. Does anyone know, roughly, what the refresh rate of the 3216 Sure Electronics display is? From what I could gather from the page

http://scuola.arduino.cc/en/content/controlling-sure-electronics-3216-led-matrix-arduino-uno

and from the Sure Electronics manual, it has display buffer. How often are the actual LEDs updated from this buffer? And are they strobed, or do they stay on until the next update?

What about transfer of data to the display buffer? From the above page, it looks like you need to transfer 14 bits/LED. How long does it take? How fast can you transfer the data?

Thanks a lot for any help on this.
Mark

P.S. If anyone is wondering why we're looking for fast refresh and transfer rates, let me say what the application is: to study human vision during saccades, which are very fast eye movements. The eye moves so fast, in fact, that 1000 Hz or higher update rates are required.

Grumpy_Mike

All matrices use multiplexing, it is likely that they also use them at the slowest rate you can get away with, that is refresh of just over 32 times a second.
If you want to do anything fancy like this then it is possible to write your own refresh routine or make your own hardware.

wexler

Hi, Mike. When you say 32 refreshes/second, is that a guess, or have you found evidence for this?

Mark

Grumpy_Mike

That is the persistence of vision for the human eye. It is a figure that has been used for years, it is not a guess.

wexler

My question was actually about the 3216 display. If anyone has any firm information about how fast it refreshes itself, I'd be very happy to know about it.

Mark

P.S. This is off-topic, but I'm not sure where that 32 frames/sec number comes from. Most people can detect, and are annoyed by, a 50-60 Hz flicker, especially somewhat in the periphery of the visual field. If you take even a 100-200 Hz flicker, and make an eye movement across it (a saccade, which you perform on the average 3 times/sec), the individual flashes paint themselves on the retina, and eveything becomes jazzy and very unstable.

florinc

I don't know the number, but I can tell you that one could sometimes notice the flicker, so it's definitely under 100Hz.
Did you try asking Sure directly?

Wagner Sartori Junior

We have made some code on http://arduino.cc/forum/index.php/topic,50326.0.html and we achieve between 83 and 120 fps.

We're using this library: http://code.google.com/p/ht1632c/

wexler

This agrees with information that I got from Sure Electronics that the typical refresh rate is 97 Hz. It's too bad that there aren't faster LED arrays out there, other than the Peggy from Evil Mad Science.

florinc

Quote
It's too bad that there aren't faster LED arrays out there

You can make your own, with no refresh rate at all (the necessary LEDs on all the time). It will just consume more current.

florinc


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