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CHAPTER 14 FREQUENCY COUNTER
User’s Manual U15104EJ2V0UD
14.3 Registers Controlling Frequency Counter
The frequency counter is controlled by the following three registers.
• IF counter mode select register (IFCMD)
• IF counter control register (IFCCR)
• IF counter gate judge register (IFCJG)
(1) IF counter mode select register (IFCMD)
This register selects the input pin of the frequency counter, and selects a mode and gate time (count time).
This register is set with a 1-bit or 8-bit memory manipulation instruction.
The value of this register is reset to 00H after reset or in the STOP mode.
In the HALT mode, this register holds the value immediately before the HALT mode is set.
Figure 14-2. Format of IF Counter Mode Select Register (IFCMD)
IFCMD1 IFCMD0
Selection of frequency counter pin and mode
0
0
Disables FMIFC, AMIFC pins
Note
0
1
AMIFC pin, AMIF count mode
1
0
FMIFC pin, FMIF count mode
1
1
FMIFC pin, AMIF count mode
IFCCK1 IFCCK0
Selection of gate time
0
0
1 ms
0
1
4 ms
1
0
8 ms
1
1
Open
Note
The FMIFC and AMFIC pins are in a high-impedance state.
Remark
Bits 4 to 7 are fixed to 0 by hardware.
7
0
6
0
5
0
4
0
IFCMD1 IFCMD0 IFCCK1 IFCCK0
Symbol
IFCMD
R/W
R/W
After reset
00H
Address
FFA9H
<0>
<1>
<2>
<3>
Содержание mPD178053
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