upd78f0103hmca1-5a4-a Renesas Electronics Corporation., upd78f0103hmca1-5a4-a Datasheet - Page 99

• Manufacturer Part Number: upd78f0103hmca1-5a4-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

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5.6 Time Required to Switch Between Internal Oscillation Clock and High-Speed System Clock
high-speed system clock.
are executed using the pre-switch over clock after switching MCM0 (see Table 5-5).
speed system clock.
5.7 Time Required for CPU Clock Switchover
the pre-switchover clock for several instructions (see Table 5-6).
Bit 0 (MCM0) of the main clock mode register (MCM) is used to switch between the internal oscillation clock and
In the actual switching operation, switching does not occur immediately after MCM0 rewrite; several instructions
Bit 1 (MCS) of MCM is used to judge that operation is performed using either the internal oscillation clock or high-
To stop the original clock after changing the clock, wait for the number of clocks shown in Table 5-5.
Remarks 1. PCC: Processor clock control register
The CPU clock can be switched using bits 0 to 2 (PCC0 to PCC2) of the processor clock control register (PCC).
The actual switchover operation is not performed immediately after rewriting to the PCC; operation continues on
Note Setting is prohibited for the (A1) grade products.
Caution To calculate the maximum time, set f
Caution Setting the following values is prohibited when the CPU operates on the internal oscillation clock.
Remark The maximum time is the number of clocks of the CPU clock before switching.
Table 5-5. Time Required to Switch Between Internal Oscillation Clock and High-Speed System Clock
PCC2 PCC1 PCC0
PCC2
Set Value Before
0
0
0
0
1
0
0
Switchover
0
0
1
1
0
2. f
3. f
4. The maximum time is the number of clocks of the CPU clock before switching.
• PCC2, PCC1, PCC0 = 0, 1, 0
• PCC2, PCC1, PCC0 = 0, 1, 1
• PCC2, PCC1, PCC0 = 1, 0, 0
PCC1
PCC
XP
R
: Internal oscillation clock frequency
0
0
: High-speed system clock oscillation frequency
0
1
0
1
0
PCC2 PCC1 PCC0 PCC2 PCC1 PCC0 PCC2 PCC1 PCC0 PCC2 PCC1 PCC0 PCC2 PCC1 PCC0
0
Table 5-6. Maximum Time Required for CPU Clock Switchover
PCC0
8 clocks
4 clocks
2 clocks
1 clock
0
1
0
f
f
XP
XP
0
/f
/2f
R
R
+ 1 clock
CHAPTER 5 CLOCK GENERATOR
High-Speed System Clock →
+ 1 clock
0
Internal Oscillation Clock
16 clocks
User’s Manual U16846EJ3V0UD
4 clocks
2 clocks
1 clock
0
Note
R
= 120 kHz.
1
Set Value After Switchover
0
Time Required for Switching
16 clocks
8 clocks
2 clocks
1 clock
1
0
2 clocks
2 clocks
0
16 clocks
Internal Oscillation Clock →
8 clocks
4 clocks
High-Speed System Clock
1 clock
Note
1
1
1
16 clocks
8 clocks
4 clocks
2 clocks
0
0
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