LedBorg suitability for high speed bitstream switching?

Submitted by ferg on Mon, 02/29/2016 - 00:02

Forums:

Hi all,
I am looking at using the LEDborg (with RPi 2B) to transmit data (bits) with On/Off Keying (OOK) and was wondering if there may be limitations with switching speed, heat or rise/fall times of the LED?

I'm considering rates of 2Mbps with white light.

The LedBorg is attractive to me as a complete package for RPi but no point in purchasing it if I can't get the desired performance.

If there are alternative products I should consider, please feel free to post a link.
Thanks,
Paul

piborg's picture

piborg

Mon, 02/29/2016 - 12:07

Having has a quick look at the datasheet for the LED itself it is a bit hard to say if the light output can be switched that quickly.
Here is the datasheet: http://www.avagotech.com/docs/AV02-2589EN
You may need to contact the LED manufacturer to see if they are capable of high switching speeds.

Other things you may need to consider:

  • You will need a way to switch the GPIO pins at the same time
  • Is the Raspberry Pi capable of 2MHz updates on the GPIO header?
  • Do you have a receiving sensor capable of reacting to 2MHz changes?

ferg

Tue, 03/01/2016 - 10:05

Thanks for the response.
- I'll have to work on that switching issue.

- Using various methods you can get quite high switching of GPIO's. See an example below; http://codeandlife.com/2012/07/03/benchmarking-raspberry-pi-gpio-speed/

- There are quite a few photodiodes that can pick up this kind of bitstream and is probably the easier part of the project. The input does need to be filtered and them amplified, before being processed.

I've also sent an enquiry to AVAGO regarding their LED performance. I checked the datasheet prior to posting and noticed that there wasn't a frequency response graph. Thanks for your help.

I'll do a bit more research into this and will hopefully purchase one soon.
Cheers!!

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