rpm counter using ir and 8051

[zulfiqq]

anyone, please give me CIRCUIT AND CODE OF 8051 USING IR, and also a circuit of db25 connection, which is for interfacing with computer,

 

[papunblg]

Here is a picture COM1 port and 8051.


Search this forum with "8051 max233" or "8051 serial communication" you will see lots of posts

And for RPM counter, It would be better if you provide us with some more details about the thing whose RPM you want to count.

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If you use DB9 pin 2 means Rx (data reception) pin 3 is TX and pin 5 is Signal ground , in DB25 pin 2 is Tx (data transmission) pin 3 is Rx and pin 7 is signal ground.
Assuming you have DB9 and pin2 is RS-232 Rx, it has to be connected to MAX232 pin 13 (or 8 ). Pin 12 (or 9) will go to your microcontroller Rx ..
MAX232 pin14(7) will be connected to RS-232 (DB9) pin3 to transmit data from your microcontroller to PC and in this case pin 11(10) ..

---------- Post added at 12:14 ---------- Previous post was at 12:10 ----------

See 8051/AT89S52 based RPM meter using Mouse Encoder :8051/AT89S52 based RPM meter using Mouse Encoder - Telecommunication and Electronics Projects

with code

---------- Post added at 12:20 ---------- Previous post was at 12:14 ----------

Homemade Microcontroller Based RPM Meter - Video
Another new kind of : AN #138 - RPM meter and rotational speed sensor KMI15/1 with AT90S2313 - MCS Electronics