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CHAPTER 14 FREQUENCY COUNTER
User’s Manual U15104EJ2V0UD
(3) Error of frequency counter
The error of the frequency counter includes an error of gate time and a count error.
(1) Error of gate time
The gate time of the frequency counter is created by dividing 4.5 MHz.
Therefore, if 4.5 MHz is shifted “+x” ppm, the gate time is also shifted “–x” ppm.
(2) Count error
The frequency counter counts the frequency at the rising edge of the input signal.
If a high level is input to the pin when the gate is opened, therefore, one excess pulse is counted. When
the gate is closed, however, counting is not affected by the status of the pin.
Therefore, the count error is “m 1”.