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CHAPTER 5 CLOCK GENERATOR
Preliminary User’s Manual U16035EJ1V0UM
Table 5-3. Maximum Time Required for CPU Clock Switchover
Set Value Before
Set Value After Switchover
Switchover
CSS PCC2 PCC1 PCC0 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
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
1
×
×
×
0
0
0
0
16 instructions
16 instructions
16 instructions
16 instructions
f
X
/2f
XT
instruction
(128 instructions)
0
0
1
8 instructions
8 instructions
8 instructions
8 instructions
f
X
/4f
XT
instruction
(64 instructions)
0
1
0
4 instructions
4 instructions
4 instructions
4 instructions
f
X
/8f
XT
instruction
(32 instructions)
0
1
1
2 instructions
2 instructions
2 instructions
2 instructions
f
X
/16f
XT
instruction
(16 instructions)
1
0
0
1 instruction
1 instruction
1 instruction
1 instruction
f
X
/32f
XT
instruction
(8 instructions)
1
×
×
×
1 instruction
1 instruction
1 instruction
1 instruction
1 instruction
Remarks 1.
One instruction is the minimum instruction execution time with the pre-switchover CPU clock.
2.
Figures in parentheses are for operation with f
X
= 8.38 MHz and f
XT
= 32.768 kHz.
Caution
Selection of the CPU clock cycle dividing factor (PCC0 to PCC2) and switchover from the main
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 dividing factor
(PCC0 to PCC2) and switch over from the subsystem clock to the main system clock (changing
CSS from 1 to 0).
