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CHAPTER 14 FREQUENCY COUNTER
User’s Manual U15104EJ2V0UD
(2) IF counter control register (IFCCR)
This register starts counting by the IF counter register and clears the IF counter register.
IFCCR is set with a 1-bit or 8-bit memory manipulation instruction.
The value of this register is reset to 00H after reset and in the STOP mode.
In the HALT mode, this register holds the value immediately before the HALT mode is set.
Figure 14-3. Format of IF Counter Control Register (IFCCR)
IFCST
Setting of IF counter register start
0
Nothing is affected
1
Starts counting
IFCRES
Setting of data clear of IF counter register
0
Nothing is affected
1
Clears data of IF counter register
Remark
Bits 2 to 7 are fixed to 0 by hardware.
(3) IF counter gate judge register (IFCJG)
This register detects opening/closing of the gate of the frequency counter.
The value of this register is reset to 00H after reset and in the STOP mode.
In the HALT mode, this register holds the value immediately before the HALT mode is set.
Figure 14-4. Format of IF Counter Gate Judge Register (IFCJG)
IFCJG0
Detection of opening/closing of frequency counter gate
0
Gate is closed
1
• If gate time is set to other than open
Status until gate is closed after IFCST has been set to 1
• If gate time is set to open
Status where gate is open as soon as it has been set to be opened
Remark
Bits 1 to 7 are fixed to 0 by hardware.
Caution
IFCJG0 remains set even if the IF counter register overflows and stops counting, until the
set gate time expires.
7
0
6
0
5
0
4
0
3
0
2
0
IFCST IFCRES
Symbol
IFCCR
R/W
W
After reset
00H
Address
FFACH
<0>
<1>
7
0
6
0
5
0
4
0
3
0
2
0
1
0
IFCJG0
Symbol
IFCJG
R/W
R
After reset
00H
Address
FFABH
<0>
Содержание mPD178053
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