UPD17016 Datasheet, PDF (247/324 Pages) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17016, 17017
20.4.3 Gate operation of IF counter
(1) When 1, 4, or 8 ms is selected as gate time
The gate is opened for 1, 4, or 8 ms since the internal 1-kHz signal has risen after the IFCSTRT flag was set
to “1”, as shown below.
While this gate is open, the frequency input from the pin is counted by the 16-bit counter.
When the gate is closed, the IFCGOSTT flag is reset.
The IFCGOSTT flag is automatically set to “1” when the IFCSTRT flag has been set.
Internal 1 kHz
H
L
1 ms
OPEN
CLOSE
Gate
time
4 ms
8 ms
Count period (IFCGOSTT flag = 1)
Gate is actually opened at this point.
Sets IFCSTRT flag.
IFCGOSTT flag is set at this point.
End of counting.
IFCGOSTT flag
is reset.
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