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ParallelPort and SD performance


#1

I’m considering a project where I’d like to do time lapse photography with a Panda II. I’d be using a cheap video camera unit which uses I2C for control and an 8-bit interface for data. The data output is JPEG, so it’s not full frames.

I’d like to write this data straight to SD without any processing at all. I’m wondering if anyone has any experience with this sort of thing, and whether anyone has rough estimates as to how fast it’s possible to write to SD, and how fast it’s possible to read using the ParallelPort class.


#2

This? :slight_smile: http://www.microframework.nl/2009/10/19/timelapse-using-micro-framework/


#3

Hi godefroi,

I have a VS6724 module in the parts box.

http://pdf1.alldatasheet.com/datasheet-pdf/view/217887/STMICROELECTRONICS/VS6724.html

I did an Eagle library for it and an initial layout but never got around to finishing the project - mainly because I got stuck making the SMD PCB. Those pads are small!

I’d like to collaborate with you on this if you want- particularly on the driver because it will probably be quite a bit of work.

Regarding the speed…

The feeling on the forums seem to suggest between 200 kilobytes to 470 kilobytes per second. That should snap a pretty decent size JPEG in less than a second (I hope!)

It is easy enough to test… I’ll see if I can rig up a little test over the weekend.


#4

I was hoping to use something like this: http://www.sparkfun.com/products/8668

1.3MP for $10 is a true bargain.


#5

[quote]I was hoping to use something like this: http://www.sparkfun.com/products/8668

1.3MP for $10 is a true bargain.[/quote]

Those need special micro with built in camera interface.


#6

It’s just an 8-bit parallel data interface, plus I2C for control, is it not?


#7

Yes, it is a “normal” parallel port, with Horizontal sync, Vertical sync and the parallel data running at 6MHz or more. On top of that, most of those cameras do not have complete data sheets, with people not getting it to run even on micros with camera ports…

The I2C registers are never described well enough either. Which you will see on the Sparkfun product page with people complaining about not getting it to actually give pictures…


#8

http://www.4dsystems.com.au/prod.php?id=75 :slight_smile:


#9

Just want to point out that the STM32 line has the required dedicated camera interface hardware ;D