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ayan_m
01-28-2005, 04:46 PM
hi,
I am trying to connect my uC with TSOP 1738 reciever/IR led pair. When I use my reciever and led without putting in the microcontroller and transfer the output to a NOT gate and connect another Led at the end of the NOT gate. The reciever is able to detect a wall or an obstacle coz' the Led connected to the NOT gate glows pretty bright but when I give the output of the reciever to the microcontroller port 1.1 the microcontroller does seem to
pick up the input and perform the necessary function.
Pls advice
ayan
The IR led is connected to a normal DC supply and so is the reciever. Also this could be a stupid doubt as it is my first time working with a microcontroller.

ice
01-28-2005, 10:48 PM
Two points:

1> are u bringing both the IR receiver and the micro to the same ground?
...both the circuits must be at the same ground level

2>which micro r u working on.Is ur code correct for receiving the signal.Post ur code snip here.If its in microchip assembly i may be able to help.


..ice

ayan_m
01-30-2005, 08:59 AM
I'd like to clear one doubt of mine. It says in the datasheet that the TSOP 1738 receives nething near and about 38Khz . If that is the case then should I be giving input at 38Khz to my IR led, if yes then how do I do it ?
Also what is the output of TSOP1738 like.

thanx
ayan

01-31-2005, 07:24 AM
Maybe this article can help you understand the IR protocol, it also uses TSOP1738

http://www.sunrom.com/product_info.php?products_id=276

ice
02-01-2005, 05:08 AM
Tht was a nice write up..nicely documented!




Also what is the output of TSOP1738 like.
Its inverted.When it sees a valid signal..it switches the output low..
Theres an animation in the above mentioned link. which may help..

ayan_m
02-06-2005, 09:21 AM
hi,
Thanx for the page. really helped me but I'm still having a problem now the things is that when I connect the IR led to my uC for the 38Khz pulse it works perfectly. but when I take the i/p from the reciever to the uC and back to an LED just to see if the uC detected it the LED glows for a flash and then dies out again. I think there is something wrong with my program pls check
ORG 0H
CLR P0.3
CLR P0.2
SETB P0.1
MOV TMOD,#10H
AGAIN:
MOV TH1,#0FFH
MOV TL1,#0E6H
SETB TR1
HERE:
JNB P0.1,NEXT ; input to uC via a NOT gate from the reciver 1738
SETB P0.3; connected to LED to check whether the input was picked up
JMP HERE1
NEXT :
CLR P0.3
HERE1:JNB TF1,HERE
CLR TR1
CPL P0.2; connected to the IR LED supplying the 38KHz
CLR TF1
JMP AGAIN
END
ayan
P.S: also pls check if this is correctly giving 38KHz

farzan
02-06-2005, 10:24 AM
do not directly connect the 38kHZ to ur led tsop1738 will not work. connect a burst frequency of within 1khz with 38k and drive the led properly using a transistor or a darlington pair

vikas
02-06-2005, 12:51 PM
like farzan said do not connect it directly ... use proper coupling .

ice
02-06-2005, 01:09 PM
but when I take the i/p from the reciever to the uC and back to an LED just to see if the uC detected it the LED glows for a flash and then dies out again.

I didnt get wht u said..
can u post a rough circuit?

dhruv
08-06-2005, 02:45 AM
hey,
whats with the burst frequency thing.... i didn't get it... can u please explain more
besides we just made two TSOP1738 sensors with just 38-39kHz from a 555 timer and it works perfectly fine!! no o/p drops and all. we've used it coupled with motors and it still works!!
Can you guys please tell me what is this burst frequency thing??
awaiting u r reply,
dhruv

maxasimo
08-06-2005, 10:39 AM
go thru the datasheet of TSOP1738....it is optimised to receive only 38 kHz IR beams, and no more than 70 pulses of IR beam at once...so u have to give it at most 70 pulses of 38kHz...only then it will work...

tpsbpl
09-14-2005, 11:42 PM
REMEMBER TSOP 1738 GIVES LOW (NEGETIVE) WHEN IT DETECT 38KHz SIGNAL
TPSBPL :idea: