168
CHAPTER 7 CLOCK GENERATOR
Table 7-3. Maximum Time Required for CPU Clock Switchover
×
×
××
1
000
1100
100 01000
CSS
00 0
0×
PCC0
PCC1
PCC2
1×
1
PCC0
CSS PCC2 PCC1
0
00
011
00
0
1
00
0
0
1
×
1
××
18 instructions
2 instructions
4 instructions 4 instructions
16 instructions
2 instructions
8 instructions
4 instructions 4 instructions
2 instructions
16 instructions 16 instructions 16 instructions
8 instructions 8 instructions
2 instructions
fX/2fXT instruction
(77 instructions)
fX/4fXT instruction
(39 instructions)
fX/8fXT instruction
(20 instructions)
fX/32fXT instruction
(5 instructions)
fX/16fXT instruction
(10 instructions)
fX/4fXT instruction
(39 instructions)
fX/8fXT instruction
(20 instructions)
fX/32fXT instruction
(5 instructions)
fX/16fXT instruction
(10 instructions)
fX/64fXT instruction
(3 instructions)
MSC = 1 MSC = 0
Set Values After Switchover
Set Values before
Switchover
CSS CSS CSS CSS CSS
1 instruction 1 instruction
1 instruction
1 instruction
1 instruction1 instruction1 instruction
CSS
1 instruction
1 instruction
Remarks 1. One instruction is the minimum instruction execution time with the pre-switchover CPU clock.2. MCS: Oscillation mode selection register (OSMS) bit 03. Figures in parentheses apply to operation with fX = 5.0 MHz and fXT = 32.768 kHz.Caution Selection of the CPU clock cycle scaling factor (PCC0 to PCC2) and switchover from the main systemclock to the subsystem clock (changing CSS from 0 to 1) should not be performed simultaneously.Simultaneous setting is possible, however, for selection of the CPU clock cycle scaling factor (PCC0 toPCC2) and switchover from the subsystem clock to the main system clock (changing CSS from 1 to 0).
PCC0
PCC1
PCC2
PCC1
PCC2 PCC0
PCC1
PCC2 PCC0
PCC1
PCC2 PCC0
PCC1
PCC2 PCC0
PCC1
PCC2 PCC0