POWER SAVING FUNCTIONS
16.1 Overview
16.1.2 Particular function select register 1
Figure 16.1.3 shows the structure of the particular function select register 1.
b7 b6 b5 b4 b3 b2 b1 b0
Particular function select register 1 (Address 6316
)
0
0
Bit
0
Bit name
Function
At reset R/W
0 : Normal operation.
1 : During execution of STP instruction
STP-instruction-execution
status bit
(Note 1) RW
(Note 2)
0 : Normal operation.
1 : During execution of WIT instruction
WIT-instruction-execution
status bit
1
(Note 1) RW
(Note 2)
Fix this bit to “0.”
0
0
2
3
RW
0 : In the wait mode, system clock fsys is active.
1 : In the wait mode, system clock fsys is inactive.
System clock stop select bit
at WIT
RW
(Note 3)
0
0
0
RW
—
4
5
6
Fix this bit to “0.”
The value is “0” at reading.
Timer B2 clock source select bit
(Valid in event counter mode.)
(Note 4)
0 : External signal input to the TB2IN pin is counted.
1 : fX32 is counted.
RW
—
The value is “0” at reading.
0
7
Notes 1: At power-on reset, this bit becomes “0.” At hardware reset or software reset, this bit retains the value just before reset.
2: Even when “1” is written, the bit status will not change.
3: Setting this bit to “1” must be performed just before execution of the WIT instruction. Also, after the wait state is termi-
nated, this bit must be cleared to “0” immediately.
4: When using timer B2 in the pulse period/pulse width measurement mode, be sure to clear this bit to “0.”
Fig. 16.1.3 Structure of particular function select register 1
(1) System clock stop select bit at WIT (bit 3)
Setting this bit to “1” makes the following clocks inactive in the wait mode: the operating clocks for
the internal peripheral devices and fsys. (Refer to section “16.2 Inactivity of system clock in wait
mode.”)
7905 Group User’s Manual Rev.1.0
16-5
RENESAS [ RENESAS TECHNOLOGY CORP ]
