upd78f0134hgka1-9et-a Renesas Electronics Corporation., upd78f0134hgka1-9et-a Datasheet - Page 131

• Manufacturer Part Number: upd78f0134hgka1-9et-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

5.7 Time Required for CPU Clock Switchover
register (PCC).
the pre-switchover clock for several instructions (see Table 5-6).
clock can be ascertained using bit 5 (CLS) of the PCC register.
CSS PCC2 PCC1 PCC0
Set Value Before
0
1
The CPU clock can be switched using bits 0 to 2 (PCC0 to PCC2) and bit 4 (CSS) of the processor clock control
The actual switchover operation is not performed immediately after rewriting to the PCC; operation continues on
Whether the system is operating on the high-speed system clock (or internal oscillation clock) or the subsystem
Cautions 1. Selection of the CPU clock cycle division factor (PCC0 to PCC2) and switchover from the
Remarks 1. The maximum time is the number of clocks of the pre-switchover CPU clock.
Switchover
0
0
0
0
1
0
0
1
1
0
2. Figures in parentheses apply to operation with f
0
1
0
1
0
2. Setting the following values is prohibited when the CPU operates on the internal oscillation
high-speed system clock to the subsystem clock (changing CSS from 0 to 1) should not be
set simultaneously.
Simultaneous setting is possible, however, for selection of the CPU clock cycle division
factor (PCC0 to PCC2) and switchover from the subsystem clock to the high-speed system
clock (changing CSS from 1 to 0).
clock.
CSS PCC2 PCC1 PCC0 CSS PCC2 PCC1 PCC0 CSS PCC2 PCC1 PCC0 CSS PCC2 PCC1 PCC0 CSS PCC2 PCC1 PCC0 CSS PCC2 PCC1 PCC0
0
CSS, PCC2, PCC1, PCC0 = 0, 0, 1, 0
CSS, PCC2, PCC1, PCC0 = 0, 0, 1, 1
CSS, PCC2, PCC1, PCC0 = 0, 1, 0, 0
8 clocks
4 clocks
2 clocks
1 clock
1 clock
0
Table 5-6. Maximum Time Required for CPU Clock Switchover
0
0
0
16 clocks
4 clocks
2 clocks
1 clock
1 clock
0
CHAPTER 5 CLOCK GENERATOR
0
User’s Manual U16899EJ3V0UD
1
0
16 clocks
8 clocks
2 clocks
Set Value After Switchover
1 clock
1 clock
0
1
XP
0
= 16 MHz and f
0
16 clocks
8 clocks
4 clocks
1 clock
1 clock
0
1
1
XT
= 32.768 kHz.
0
16 clocks
8 clocks
4 clocks
2 clocks
1 clock
1
0
0
1
2f
f
f
f
f
XP
XP
XP
(977 clocks)
(489 clocks)
(245 clocks)
(123 clocks)
XP
(62 clocks)
XP
/2f
/4f
/8f
/f
/f
XT
XT
XT
XT
XT
clocks
clocks
clocks
clocks
clocks
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