PD17012_15 Datasheet, PDF (202/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17012, 17P012
17.3 Start/Stop Control Block and IF Counter
17.3.1 Configuration of start/stop control block and IF counter
Figure 17-5 shows the configuration of the start/stop control block and IF counter.
The start/stop control block starts the frequency counter or detects the end of counting.
The counter is started by the IF counter control register.
The end of counting is detected by the IF counter gate judge register. When the external gate counter function
is used, however, the end of counting cannot be detected by the IF counter gate judge register.
Figure 17-6 shows the configuration of the IF counter control register.
Figure 17-7 shows the configuration of the IF counter gate judge register.
17.3.2 and 17.3.3 describe the gate operation when the IF counter function is selected and that when the external
gate counter function is selected.
The IF counter is a 16-bit binary counter that counts up the input frequency when the IF counter function or external
gate counter function is selected.
When the IF counter function is selected, the frequency input to a selected pin is counted while the gate is opened
by an internal gate signal. The frequency count is counted without alteration in the AMIF count mode. In the FMIF
counter mode, however, the frequency input to the pin is halved and counted.
When the external gate counter function is selected, the internal frequency is counted while the gate is opened
by the signal input to the pin.
When the IF counter counts up to FFFFH, the following input becomes 0000H, and then counting continues.
The count value is read by the IF counter data register (IFC) via data buffer.
The count value is reset by the IF counter control register.
Figure 17-8 shows the configuration of the IF counter data register.
Figure 17-5. Configuration of Start/Stop Control Block and IF Counter
DBF
16
IFCSTRT flag
IFCG flag
IFCRES flag
From gate time
select block
Gate signal
Frequency
Start/Stop
control
IF counter data
register (IFC)
16
RES
IF counter
(16 bits)
200
Data Sheet U10101EJ4V0DS