View Full Version : ir sensor and 555

08-19-2007, 07:50 PM
hi guys,
i need to interface an ir sensor with pic89c51.so i used 555 of this purpose.
but my ckt did not work.i wasnt getting logic 1 or 0 from the o/p pin .
plz suggest me howe to interface it with a pic.so dat i can use logic 1 or 0.

plz help me


08-19-2007, 08:39 PM
Hi there,
These articles might prove useful: http://www.triindia.co.in/resources/?page_id=56

Mohit Bhoite

08-23-2007, 12:09 AM
You have not specified the type of IR sensor that you have used.
Most of the sensors can be directly coupled to a Microcontroller. There is no need for a 555 ckt.
Any other interface needs to be strongly justified and will need some design calculations.

08-26-2007, 12:16 AM
yea i am using tsop 1738....
if i interface it directly it to a microcontroller--what do i get as input..
if i make this 555 ckt i can get an logic 1 or 0 input to the microcontroller.
if i do not use this 555-what i need to program in the microcontroller
plz help me in this regard... i got stuck at this sensor ckt...


08-26-2007, 02:01 AM
The TSOP will go LOW on sensing 38KHz BURST IR signal.
If you need an active high logic for the 8051, use a 7lls04 (NOT gate) inverter section. This is the easiest to set the logic.

08-26-2007, 02:07 AM
do u say it comes to zero when it senses i.e logic 0 if not how will we detect the voltage drop with the microcontroller


08-26-2007, 09:11 PM
..... if not how will we detect the voltage drop with the microcontroller

I did'nt understand!
Read the TSOP1738 datasheet. The normal O/P is 5V and changes to 0V when it detects mod IR.
The 8051 will detect the change in logic: 5V= Hi, <2v= Lo......

08-27-2007, 12:36 AM
thanx for ur reply...
yea i will test the ir emitter ckt given for 38khz in thic forum.i think i need to change the resistors values to bring change in the freq.can i use microcontroller for ir emmission.if yes plz tell me how to produce 38 khz with 89c51.what wud be the logic.plz help me as my dates are nearing


09-01-2007, 02:50 AM
i need to interface an ir sensor with pic89c51.
i think you are talking about
AT89c51 :roll:

09-01-2007, 10:14 AM
i need to interface tsop1738 with at89c51.plz help me with this.