Microcontroller-based Ta chometer
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Testing
The source code of this article is available
at
com/efycodes/efy-codes.zip at code
file ‘tacho.hex.’ Using a programmer,
load the code into the new chip
AT89C2051. (Refer the May 2005 issue
of EFY for article on programmer for
89C51 and 2051.) Then, fit it into the
circuit board and after powering up the
circuit, test it.

Software
The software is written in Assembly
language and assembled using 8051
cross-assembler. It is well commented
and easy to understand. It uses
AT89C2051’s internal timer for measuring
the period of one cycle of the
rotation in units of 100 microseconds.
Thus if the speed is 1500 rpm, it is 25
rps, and the time taken for one cycle
is 40 ms.