infrared communication

[Eros]

<font face="Courier New" size=-1>I m doing the infrared data sending and receiving using the pic 16f877.but i can't find any infrared communication library file or the examble souce code from the ccs for me to refer..
can i use the rs232 concept using the infrared instead of cable connect
i m lost,and dun't know how to start, do somebody have idea..


ThankQ



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This message was ported from CCS's old forum
Original Post ID: 2829

[johnpcunningham]

Infrared is just a transfer medium, like RF wireless or a cable. You can use RS232 to transfer data through Infrared just like using a cable. RS232 typically uses drivers (ie MAX232) to invert the voltages and increase the drive cababilities, but since you are going wireless, this does not pose a problem. Just make sure the receive side signals matches the transmit side signals.

One thing to point out is that you wont have any handshaking capabilities and error correction gets tough if you are trying to transmit data where other IR is being transmitted. You might need an error correction scheme like Reed_Solomon or some other type of correction. But that is beyond the scope of this email.

JC
___________________________
This message was ported from CCS's old forum
Original Post ID: 2844

[Eros]

:=Infrared is just a transfer medium, like RF wireless or a cable. You can use RS232 to transfer data through Infrared just like using a cable. RS232 typically uses drivers (ie MAX232) to invert the voltages and increase the drive cababilities, but since you are going wireless, this does not pose a problem. Just make sure the receive side signals matches the transmit side signals.
:=
:=One thing to point out is that you wont have any handshaking capabilities and error correction gets tough if you are trying to transmit data where other IR is being transmitted. You might need an error correction scheme like Reed_Solomon or some other type of correction. But that is beyond the scope of this email.
:=
:=JC


ThanQ for u reply
refer to ur saying,the error checking and the handshaking also are the problems..
That is why i m no sure the rs232 is do able or not,if not using rs232, what methods else i can use?
(my concept is use the software flow control, add the start bit, stop bit and error checking on the data... do anyone have other idea or comment )

Eros :>
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This message was ported from CCS's old forum
Original Post ID: 2855

[John Purbrick]

If you attempt to have the IR sent out strictly the way a serial port works, i.e. LED is on for 1/9600 sec per bit if you selected 9600 Baud, I'm afraid you'll have a miserably poor range and the system won't work well, and it'll be subject to total death if there are incandescent lights or sunlight anywhere near.

One method that works well across a room is to use TV remote control receivers, and modulate the LED at the required frequency (40KHz or 38KHz are common). If the PIC has time to do this it can do it directly, or you can use an external oscillator. I've tried the TV decoders and they work, but you have to accept a fairly low Baud rate--1.2KB worked but I had trouble at 2.4KB. Note that 40KHz actually means 80000 interrupts per second, as you need one to turn the LED on and another to turn it off!
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This message was ported from CCS's old forum
Original Post ID: 2872

[Dennis Clark]

IR commo is no problem, as long as you don't set your sights
too high. I have used 2400 N81 over IR at distances of a
several feet via Parallax Stamps and PIC12C508 bit-banging with
no problems in full indoor lighting conditions. With the
Stamp II I used inverted serial out and with PICs I've used
my own 40KHz modulation routines to send bit-banged serial.
The key to remember is that the IR demodulator will read a
"signal present"(saw modulation) as a '0' and a lack of signal
as a '1'. Make sure you set up your transmitter and receiver
such that they agree on this protocol! In trivial cases I
didn't bother with error detection or correction as commands
were usually repeated anyway. Where it is important you can
take a leaf from the LEGO Mindstorms RCX IR protocol. They
used 8 bit WITH even parity, sent each byte normal and inverted
and used a checksum at the end of the series. This is most
paranoid but was rock solid. Pick your pain level. If you
want to see an example of IR serial I/O using PIC code and
being bit-banged, check my web page at
<a href="http://www.techtoystoday.com" TARGET="_blank">http://www.techtoystoday.com</a> and bonk on the "sensor projects"
link and look for the IR transmitter/receiver project.

have fun,
DLC

:=:=Infrared is just a transfer medium, like RF wireless or a cable. You can use RS232 to transfer data through Infrared just like using a cable. RS232 typically uses drivers (ie MAX232) to invert the voltages and increase the drive cababilities, but since you are going wireless, this does not pose a problem. Just make sure the receive side signals matches the transmit side signals.
:=:=
:=:=One thing to point out is that you wont have any handshaking capabilities and error correction gets tough if you are trying to transmit data where other IR is being transmitted. You might need an error correction scheme like Reed_Solomon or some other type of correction. But that is beyond the scope of this email.
:=:=
:=:=JC
:=
:=
:=ThanQ for u reply
:=refer to ur saying,the error checking and the handshaking also are the problems..
:=That is why i m no sure the rs232 is do able or not,if not using rs232, what methods else i can use?
:=(my concept is use the software flow control, add the start bit, stop bit and error checking on the data... do anyone have other idea or comment )
:=
:=Eros :>
___________________________
This message was ported from CCS's old forum
Original Post ID: 2875

[Magic_Pilot]

you can use rs232 protocol but you must also use data check eg
you can send a string following format #data1*data1# and check it in receiver.



:= IR commo is no problem, as long as you don't set your sights
:=too high. I have used 2400 N81 over IR at distances of a
:=several feet via Parallax Stamps and PIC12C508 bit-banging with
:=no problems in full indoor lighting conditions. With the
:=Stamp II I used inverted serial out and with PICs I've used
:=my own 40KHz modulation routines to send bit-banged serial.
:=The key to remember is that the IR demodulator will read a
:="signal present"(saw modulation) as a '0' and a lack of signal
:=as a '1'. Make sure you set up your transmitter and receiver
:=such that they agree on this protocol! In trivial cases I
:=didn't bother with error detection or correction as commands
:=were usually repeated anyway. Where it is important you can
:=take a leaf from the LEGO Mindstorms RCX IR protocol. They
:=used 8 bit WITH even parity, sent each byte normal and inverted
:=and used a checksum at the end of the series. This is most
:=paranoid but was rock solid. Pick your pain level. If you
:=want to see an example of IR serial I/O using PIC code and
:=being bit-banged, check my web page at
:= <a href="http://www.techtoystoday.com" TARGET="_blank"> <a href="http://www.techtoystoday.com" TARGET="_blank">http://www.techtoystoday.com</a></a> and bonk on the "sensor projects"
:=link and look for the IR transmitter/receiver project.
:=
:=have fun,
:=DLC
:=
:=:=:=Infrared is just a transfer medium, like RF wireless or a cable. You can use RS232 to transfer data through Infrared just like using a cable. RS232 typically uses drivers (ie MAX232) to invert the voltages and increase the drive cababilities, but since you are going wireless, this does not pose a problem. Just make sure the receive side signals matches the transmit side signals.
:=:=:=
:=:=:=One thing to point out is that you wont have any handshaking capabilities and error correction gets tough if you are trying to transmit data where other IR is being transmitted. You might need an error correction scheme like Reed_Solomon or some other type of correction. But that is beyond the scope of this email.
:=:=:=
:=:=:=JC
:=:=
:=:=
:=:=ThanQ for u reply
:=:=refer to ur saying,the error checking and the handshaking also are the problems..
:=:=That is why i m no sure the rs232 is do able or not,if not using rs232, what methods else i can use?
:=:=(my concept is use the software flow control, add the start bit, stop bit and error checking on the data... do anyone have other idea or comment )
:=:=
:=:=Eros :>
___________________________
This message was ported from CCS's old forum
Original Post ID: 2891

[cxiong]

I am working on a project using IR communication, I have the transmitter
and the receiver talking, but the data are junk per hypertminal.

Per the code below, it should display (0123456789), but it display (c3f2dcged).

I USE THE IRLED from RadioShack 276-0143 for the TX and I use the
Panasonic PNA4602M for the receiver. I generate a 39Kh (PWM) for the
transmitter to match up the receiver freq.

I connect them to 2 of the Demo 2 Plus board.

Any body have any idea what did I did wrong?
Here is my code:

///RECEIVER////

[Mark]

That receiver is a 38KHz version. Why are you using 39KHz? Try a value of 130 for PR2. You will have to adjust the duty cycle as well. You can also take a scope and look at the output of the PNA4602M and compare this to the output of the serial data. They ought to be the same.

[SherpaDoug]

[Hans Wedemeyer]

[cxiong]

When I re-adjust the PR2 to 130, I measure it with the O'scope, I have 38.4Khz.

The data display in the hyperterminal still the same as above. It does not solve the problem.

I change from printf("%d\n",c); to putc(c), no different. I measure the data out (data_pin )of transmitter compare it to the data out of receiver, they are different.

At the transmitter side, the scope show more like the 38.4Khz clock with some noise.

At the receiver side, the scope show a data line (more like serial data signal, such 01010001).

Below is my circuit.


Transmitter connect to 1st Demo 2 Plus board.


Receiver connect to the 2nd Demo 2 Plus board.

Will the above software work for these circuits?

[cxiong]

Infrared data conversion, does it need to have a MAX 232 between the receiver and the PC port?

[Mark]

[cxiong]

I have the receiver send the received data to hyperterminal.
Here is what I got from the Hyperteminal:



Here is my latest transmit code:

[Humberto]

cxiong wrote: