Author Topic: looking for IR transceiver  (Read 2405 times)

0 Members and 1 Guest are viewing this topic.

Offline AdminTopic starter

  • Administrator
  • Supreme Robot
  • *****
  • Posts: 11,653
  • Helpful? 169
    • Society of Robots
looking for IR transceiver
« on: March 04, 2008, 02:39:07 PM »
I'm looking for an off the shelf (not homemade, involving minimal wiring) infrared transceiver that I can directly hook up to Tx and Rx of my microcontroller (not rs232!), but I can't seem to find one.

I only require about 4 feet direct line of sight range. A maximum range of 10 feet or less is best, but not a requirement. Yeap you read it right, long range is bad for this project!

The best I can find is this stuff:
http://www.rentron.com/PicBasic/RemoteControl.htm

and this receiver:
http://www.sparkfun.com/commerce/product_info.php?products_id=8554#

but none of that meets all my requirements . . .

edit: also found this http://iguanaworks.net/product2.psp but looking for other options
« Last Edit: March 04, 2008, 03:08:47 PM by Admin »

Offline frank26080115

  • Supreme Robot
  • *****
  • Posts: 322
  • Helpful? 2
Re: looking for IR transceiver
« Reply #1 on: March 04, 2008, 03:30:29 PM »
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16564
datasheet for above product
http://www.infrarotport.de/tfd_4.pdf

3 meter range can be selected with a sensitivity selecting pin

Lemme guess... You need IRID?
« Last Edit: March 04, 2008, 04:37:57 PM by frank26080115 »

Offline paulstreats

  • Supreme Robot
  • *****
  • Posts: 1,381
  • Helpful? 21
Re: looking for IR transceiver
« Reply #2 on: March 04, 2008, 04:15:25 PM »
I know that your looking at an off the shelf product, but micro chip do an ir transciever chip http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010407

sparkfun do these lovely ir transmitter/reciever pairs http://www.sparkfun.com/commerce/product_info.php?products_id=246 - it says a detection range of a few cms, but ive used it over 3 feet. And of course you wont be relying on a reflected signal, so it will work slightly further for you.

Coupled with one of these enclosures http://www.okw.co.uk/products/okw/minitec.htm and your onto a winner

Offline dunk

  • Expert Roboticist
  • Supreme Robot
  • *****
  • Posts: 1,086
  • Helpful? 21
Re: looking for IR transceiver
« Reply #3 on: March 04, 2008, 04:33:38 PM »
so there are loads of modules that filter out the 38Khz carrier that you can connect the output pin of straight to your microcontroller's UART. they all work in a very similar way.
there's a good list on the LIRC website: http://www.lirc.org/receivers.html
(ignore the schematic on the LIRC site. you don't need it if you are connecting straight to a UART.)

that solves the receive end of your problem in a single component.

i've never seen a single component that produces a 38Khz carrier signal though. any one ever dissected a TV remote to see what they use?

i've done it 2 different ways in the past.
the way with the smallest component count is to generate the 38Khz carrier in software. then you only need to connect an IR led (with the correct resistor) to your TX pin.
obviously you won't be able to use your microcontroller's built in UART anymore because it is not setup to add the 38Khz carrier signal.
it's a nasty way to do things if you want to do anything else on the microcontroller though because you have to devote all the program to bit-banging your transmission over the 38Khz signal.
i used this method to create some IR beacons that repeated a different number for each beacon.

the better way to do it is build a 38Khz oscillator that your microcontrollers UART TX pin can enable and disable.
there is an example using an NE555 here: http://jap.hu/electronic/infrared.html
this does not match your single component requirement though.


dunk.



Offline AdminTopic starter

  • Administrator
  • Supreme Robot
  • *****
  • Posts: 11,653
  • Helpful? 169
    • Society of Robots
Re: looking for IR transceiver
« Reply #4 on: March 06, 2008, 08:40:17 AM »
hmmmm none of those options are off the shelf (meaning a lot of wiring is required) . . .

What if I don't bother with the 38Khz modulation, and just do this:

Tx -> resistor -> IR emitter LED -> ground

and

5V -> resistor -> Rx -> IR detector LED -> ground


I realize that without the modulation the signal would be susceptible to environmental interference, such as from lights in the room, etc. But I only need a max of 4 feet range . . .

Think it'll work?


I'll also contact that Iguana company and see if there is an easy hack.

Offline dunk

  • Expert Roboticist
  • Supreme Robot
  • *****
  • Posts: 1,086
  • Helpful? 21
Re: looking for IR transceiver
« Reply #5 on: March 06, 2008, 09:28:57 AM »
Quote
What if I don't bother with the 38Khz modulation, and just do this:

Tx -> resistor -> IR emitter LED -> ground

and

5V -> resistor -> Rx -> IR detector LED -> ground


I realize that without the modulation the signal would be susceptible to environmental interference, such as from lights in the room, etc. But I only need a max of 4 feet range . . .

Think it'll work?
it would work when it's completeley dark but if there is any back ground IR light it will drown out the IR emitter.
you could possibly set the trigger level at RX by varying the resistor value but you would need to recalibrate every time the light conditions change.

dunk.

Offline AdminTopic starter

  • Administrator
  • Supreme Robot
  • *****
  • Posts: 11,653
  • Helpful? 169
    • Society of Robots
Re: looking for IR transceiver
« Reply #6 on: March 13, 2008, 10:33:40 PM »
I decided to go with this Vishay Opto Transceiver:
http://www.vishay.com/docs/81288/tfdu4101.pdf
http://www.mouser.com/Search/ProductDetail.aspx?R=TFDU4101-TR3virtualkey61370000virtualkey782-TFDU4101


I had to design a PCB to use that surface mount chip, but it required zero supporting electronics or wiring, other than power/ground/tx/rx. Took me about ~3 hours. Plus, its tiny and cheap! As close to off the shelf and reliable I could get.

Ill report when I finish assembling it, and post a pic.

Offline AdminTopic starter

  • Administrator
  • Supreme Robot
  • *****
  • Posts: 11,653
  • Helpful? 169
    • Society of Robots
Re: looking for IR transceiver
« Reply #7 on: March 23, 2008, 03:29:38 PM »
I decided not to take the route of hacking the Iguana transceiver, but here is their email anyway for anyone else interested:

Quote
Take a look at the schematic for the Serial IR Transceiver at
http://iguanaworks.net/downloads/serial-schematic.pdf

The device trickle charges off of the RTS line. It only needs between 5V
and 9V at a few mA. The output of DCD is the TTL output of the IR
receiver. That would go to your receiver. Sending is a TTL input to DTR
and would connect to transmit. It only needs a few volts and ~1mA.

As for connecting, you have a few options. One you be to make your own
cable the connects to our db9 connector (serial connector) on one end
and whatever you need for your UART on the other side. Alternatively you
could desolder our serial connector and solder directly to where the
serial port connects. Or you could try to solder to the extra leads on
the serial port device for the pins -- maybe a little tricky. If you
aren't afraid of soldering, I think the easiest thing for connecting is
to get our device and look at and see what seems best. There are only 4
wires to connect (power, ground, send, receive) and I'm sure you'll be
able to make something work.

 


Get Your Ad Here