4 ms·

Similar things have been around for a while and there are several variations to be found for the AVR, using the I/O pins rather than the ADC. See US Patent 6,8

Similar things have been around for a while and there are several variations to be found for the AVR, using the I/O pins rather than the ADC. See US Patent 6,870,148 B2 March 22 2005 "LED WITH CONTROLED CAPACITIVE DISCHARGE FOR PHOTO SENSING" by Mitsubishi Electric Research Lab (MERL). https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/6870148 https://image-ppubs.uspto.gov/dirsearch-public/print/downloa... Also: Dietz, P.H., Yerazunis, W.S., Leigh, D.L., "Very Low-Cost Sensing and Communication Using Bidirectional LEDs", ACM International Conference on Ubiquitous Computing (UbiComp), October 2003. BibTeX TR2003-35 - https://www.merl.com/publications/TR2003-35 https://www.merl.com/publications/TR2003-35 Which is good for ~30 Baud and distances of inches at best. https://people.ece.cornell.edu/land/courses/ece4760/FinalProjects/s2006/bcr6/final_report/ https://people.ece.cornell.edu/land/courses/ece4760/FinalPro... https://forum.chibios.org/viewtopic.php?t=2179 https://forum.chibios.org/viewtopic.php?t=2179

bloopernova 2y ago
> Which is good for ~30 Baud and distances of inches at best. This feels like it would be part of the plot of a Neal Stephenson or Andy Weir book. Our intrepid hero has to send super secret plans to save humanity through glass to his partner, so they can prevent Jupiter going supernova! But the Bad Guys are jamming wifi signals!
- dangets 2y ago
  As a university project I created a Morse code transmitter and receiver circuit that used the same type of LED on both sides. It worked pretty well up to a few inches apart.
kragen 2y ago
the distance and baud rate depend a lot on the specific led you're using and how you're measuring it
regularfry 2y ago
I remember a project in Scientific American many years ago which proposed using a distributed bunch of sensors using reverse-biased green LEDs to measure atmospheric pollution levels, but I can't immediately find it now.
- jgrahamc 2y ago
  Probably something from Forrest Mims. I have his stuff going back to the 1970s and he was using LEDs like this for all sorts of communication and environmental stuff way back.
  - rpaddock 2y ago
    Yes. We both posted that he originated the idea at the same time.
  - regularfry 2y ago
    Very probably. This isn't it, but it's very closely related: https://www.researchgate.net/publication/243581659_LED_sun_photometry https://www.researchgate.net/publication/243581659_LED_sun_p...
  - regularfry 2y ago
    Here we go! https://web.archive.org/web/19980131092505/https://www.scientificamerican.com/0597issue/0597amsci.html https://web.archive.org/web/19980131092505/https://www.scien... Found via https://www.researchgate.net/publication/234345754_An_International_Haze-Monitoring_Network_for_Students https://www.researchgate.net/publication/234345754_An_Intern...
- rpaddock 2y ago
  Internet Search has become near useless of late, regardless of which Search Engine is used. Hopefully you find it and let us know. Forrest Mims was the first to propose using the LED as a sensor in the early 70s, not long after LEDs became common. https://hackaday.com/2015/10/13/citizenscience/ https://hackaday.com/2015/10/13/citizenscience/

bloopernova 2y ago

> Which is good for ~30 Baud and distances of inches at best. This feels like it would be part of the plot of a Neal Stephenson or Andy Weir book. Our intrepid hero has to send super secret plans to save humanity through glass to his partner, so they can prevent Jupiter going supernova! But the Bad Guys are jamming wifi signals!

dangets 2y ago
As a university project I created a Morse code transmitter and receiver circuit that used the same type of LED on both sides. It worked pretty well up to a few inches apart.

kragen 2y ago

the distance and baud rate depend a lot on the specific led you're using and how you're measuring it

regularfry 2y ago

I remember a project in Scientific American many years ago which proposed using a distributed bunch of sensors using reverse-biased green LEDs to measure atmospheric pollution levels, but I can't immediately find it now.

jgrahamc 2y ago
Probably something from Forrest Mims. I have his stuff going back to the 1970s and he was using LEDs like this for all sorts of communication and environmental stuff way back.
- rpaddock 2y ago
  Yes. We both posted that he originated the idea at the same time.
- regularfry 2y ago
  Very probably. This isn't it, but it's very closely related: https://www.researchgate.net/publication/243581659_LED_sun_photometry https://www.researchgate.net/publication/243581659_LED_sun_p...
- regularfry 2y ago
  Here we go! https://web.archive.org/web/19980131092505/https://www.scientificamerican.com/0597issue/0597amsci.html https://web.archive.org/web/19980131092505/https://www.scien... Found via https://www.researchgate.net/publication/234345754_An_International_Haze-Monitoring_Network_for_Students https://www.researchgate.net/publication/234345754_An_Intern...
rpaddock 2y ago
Internet Search has become near useless of late, regardless of which Search Engine is used. Hopefully you find it and let us know. Forrest Mims was the first to propose using the LED as a sensor in the early 70s, not long after LEDs became common. https://hackaday.com/2015/10/13/citizenscience/ https://hackaday.com/2015/10/13/citizenscience/