simple communication between two mcu's wirelessly .

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I have two avr mega chips that I want to communicate between. Each mcu is its own device. The communication will only contain two states. The communication will need to have a pin/code to discriminate between multiple products of this kind. What is a light weight simple design for such a thing? Best I can come up with is something similar to a garage door remote.

 

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Holtek makes the encoder and decoder chips for garage door openers.

 

Imagecraft compiler user

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Note that "wireless" includes IR, visible light, sound, ultrasound, etc, etc - so what, exactly, do you mean by "wireless" in this case?

 

You also haven't mentioned what range you require ...

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Last Edited: Fri. Jul 22, 2016 - 04:48 PM
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S_K_U_N_X wrote:
Best I can come up with is something similar to a garage door remote.

Cars and their remote locking are probably another good model to explore. They using a "rolling code" (a bit like a random number sequence) that is predictable. Because the car may have missed  a few key presses it usually expects one of the next 256 numbers in the sequence. If the car and the key get very out of step they need to "come together" and the key then resets back in line.

 

These nrf24L01 things that you can get on ebay for a few bucks each look like a simple solution for the actual radio implementation - it's then just a question of defining the protocol of the data that pass between the two.

 

BTW just googled to see if I could find a description of the rolling/"hopping" code thing and hit this which not only contains a description but describes a very interesting chip which might do the job for you...

 

http://www.ti.com/general/docs/l...

Last Edited: Fri. Jul 22, 2016 - 04:55 PM
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Check out AVR411.

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You also haven't mentioned what range you require ...

10 feet max

 

wireless meaning through the cabin of a car. Line of site would not work. Should be inside the care not through a trunk or anything.

 

Thx for the info, all. Ill look at these options.

 

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bobgardner wrote:
Holtek makes the encoder and decoder chips for garage door openers

I think Microchip also do?

 

clawson wrote:
... using a "rolling code" 

 

joeymorin wrote:
Check out AVR411

The full title of which is, "Secure Rolling Code Algorithm for Wireless Link"

 

http://www.atmel.com/Images/Atme...

 

http://www.atmel.com/images/AVR4...

 

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
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Counterfeit NRF24L01 modules are cheap and easy to work. I don't mess with wires more than a couple feet long any more.

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