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Author Topic: Remote Control like IR Communication between uCs  (Read 1067 times)

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Offline jonagikTopic starter

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Remote Control like IR Communication between uCs
« on: August 14, 2011, 04:13:40 PM »
Hi,

I would like to implement IR communication between two uCs. Are an ir led and photoresistor suitable? What sort of range would I get?

Thanks in advance.

Offline Soeren

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Re: Remote Control like IR Communication between uCs
« Reply #1 on: August 14, 2011, 05:03:50 PM »
Hi,

I would like to implement IR communication between two uCs.
Moving or not?
Why not a bit of wire (cheap)?
Over how large a distance?


Are an ir led and photoresistor suitable? What sort of range would I get?
It depends of what you want to accomplish and at what distance.

I have made (un-modulated) main frame interfacing at 9600 bps with IR LED's and photo diodes, but the distance was only a few mm. I removed most of the pins in D-Sub25 connectors to make room for 5 lines of IR and used the few remaining pins for charging the data loggers while they uploaded their data to the main frame and while it may sound a bit over the top, the charging was necessary, as they were only uploaded after a lot of logging, so the batteries were on the brink already and the power to the IR would often bring them down, demanding endless retransmissions or causing data loss. They needed an optical solution, as they started out with wired transfer over D-Sub25, but they connected and disconnected often enough to kill the best gold plated connectors we could find in about a month and then the transmission went haywire.

With even a modest distance the speed falls drastically, as error correction request retransmission of packets.
Next step up is to use a modulated carrier, but that won't give you that much of a data rate.

If you need a high speed IR connection, take a look at IrDA transceivers, they don't use a carrier wave, but short pulses, but will be quite usable at a short distance.

Higher speed or larger distance and you need radio.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Admin

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Re: Remote Control like IR Communication between uCs
« Reply #2 on: August 15, 2011, 01:46:04 PM »
Everything you need to know, including IR range, can be found here:
http://www.societyofrobots.com/electronics_irda_tutorial.shtml

Offline Maltaeron

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Re: Remote Control like IR Communication between uCs
« Reply #3 on: August 28, 2011, 09:26:36 PM »
I hate to disagree with admin, but it sounds like you might be looking for something a little less extensive than IR.

Read the extensive information from http://www.sbprojects.com/knowledge/ir/index.php to get to know how actual IR remotes work. Personally, I have implemented and used Sony's SIRC protocol for controlling a simple robot. As I implemented it, I simply relayed the on/off positions of 7 buttons as the 7 bits of the command I was sending. If you wanted to send arbitrary data larger than 7 bits, it might be better to use IrDA, as remote control protocols are optimized to just make sure one of several sent commands is correctly received. However, with a little more work you could probably achieve arbitrary data transmission reliably with an IR remote protocol, just at very low transmission rates.

Good luck, and for this remote method, all you would need is an ir led and an ir receiver ic (the ic has an eye to see the ir and then demodulates the carrier frequency to logic high and low).

 


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