what is the fastest IR reciever

[bloody-orc]

is it LDR, Phototransistor,Photodiode?

i need it to read pulses 3ms long and the output must not be like AC current has, but squarewaves

and as i sed IR reciever
(dont want to use IR-Recieverchip

 

[FRIED]

Photodiode in reverse bias mode.

 

[bloody-orc]

what is reverse bias mode?

would you shoot me with a schmatic (i'm usin picin 4MHz to read those pulses)

 

[FRIED]

Google is your friend
**broken link removed**
Note fig 7

 

[Nigel Goodwin]

what is reverse bias mode?

would you shoot me with a schmatic (i'm usin picin 4MHz to read those pulses)

You don't really have a speed problem, as your pulses are fairly long. But why don't you want to use an IR IC receiver? - these are very simple, very easy to use, and will probably (certainly?) greatly out perform anything you can build.

To do it with a photodiode means building high gain opamp circuits, filters, AGC circuits, detectors, and either a PLL or a slicer to produce the digital output. It will also need extremely careful PCB design (as it will easily become unstable), and will almost certainly need to be in a screened enclosure.

 

[bloody-orc]

well yes i know that this IR chip is awsome, but i dont have a ckue how to generate 38KHz pulses wit pic...

like how to send out this : 1101011011
and recieve it wit another pic...

 

[Someone Electro]

you might feed the data in an 555 Timers reset pin tuned to 38 KHz and an IR led on the output

so it shod oscilate wen the Reset is high

 

[Nigel Goodwin]

well yes i know that this IR chip is awsome, but i dont have a ckue how to generate 38KHz pulses wit pic...

like how to send out this : 1101011011
and recieve it wit another pic...

Perhaps you should read my PIC tutorials?, one of those is about IR remote control - and shows how simple it is to generate 38KHz. However, you should be aware that you can't simply send serial data over an IR link (the widths of the pulses doesn't transfer properly). My tutorial uses the Sony SIRC's system, you could easily use that to send data - however, it is fairly slow.

 

[bloody-orc]

can't actually get you tut's cause i use different cind of laguage and dont know that(yet)

but that 555 thingy... how do you thint this should be done? i mahe a 555 schem and give power to it using a transistor and pic? or does it have enable pin? I haven't worked with them so i dont really get those litte fellows

 

[Someone Electro]

You build an 555 timer oscilator like shown in the datasheet and get software to caculate the caps and resistors to tune it to 38KHz.conect an IR LED to the output and insted of puling to reset (pin 4) to Vdd you conect it to your PICs output (directly whih no trasistors)

so wenn the PICs output goes high the timer will begin to oscilate.
It only needs a few microamps to pull it up

this way you dont need transistors to switch the power to the whole thing you only start/stop the oscilaton

I used 555 timers in many of my projects

 

[Someone Electro]

or i seed someware an nifty litle desvice that you need to aply the power suply and an resistor for the intergrated IR LED

you and direclty send data in and recive it on an nother pin

the device has the trsmiter and reciver intergrated in one device (so you need 2 of them and you can send data bouth ways)i think its about 100 kb/s

 

[bloody-orc]

but how fast is this thing?
how fast is starts shooting pulses? does it need time to warm up and to stop shooting?

 

[Someone Electro]

well the timer thing shod start right awey.The 555 timer method cod trasmit about 4 kb/s (38KHz isent an high enugh feq fot fast transfres)

the litle device i mentoned uses an very high freq so data can be trasmited wery fast

any way do you need fast data transfer?(for an IR remote control the 555 timer is fast enugh )

 

[bloody-orc]

i'm trying to communicate with two pics...(actually picaxes but i think there the same)

 

[Someone Electro]

dose it work?

To try it out simply wire the reset pin of the timer to Vdd (whith no PIC conected) and give the detector IC power and hook up an LED to its output pin.So wen you pint the IR LED at it the recivers LED sod thurn on/off (when you conect/disconect the reset pin)
if it works them conect it to the PICs and try to comunicate.

 

[DirtyLude]

IrDA is generally 115k, but you can get up to 4M supposedly with the right transciever and protocol.

I'm not certain how hard it would be to bit bang an IrDA interface. My uC (Zilog) has hardware IrDA built in and it works pretty well.

 

[Nigel Goodwin]

IrDA is generally 115k, but you can get up to 4M supposedly with the right transciever and protocol.

I'm not certain how hard it would be to bit bang an IrDA interface. My uC (Zilog) has hardware IrDA built in and it works pretty well.

You certainly don't bitbang it using interpreted BASIC running off a 4MHz clock though 8)

 

[Someone Electro]

anyway why do you need to trasfer data so fast?

meaby if you cod describe your project a bit

 

[DirtyLude]

You certainly don't bitbang it using interpreted BASIC running off a 4MHz clock though 8)

Ah, good point.

I have another idea: A long cable.

 

[bloody-orc]

cable is no option and IrDa is far to expencive for me (4 times as much as a good pic)
and i dont need to transfer data fast. i just need to transfer it so tht both pic's understand that they have communicated... now all i need to do is to go to my nearest suplyer and get a 555 and some caps and put them all together and report my answers to you then

thanks for your help