upd78f0124hgba1-8et-a Renesas Electronics Corporation., upd78f0124hgba1-8et-a Datasheet - Page 99

• Manufacturer Part Number: upd78f0124hgba1-8et-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

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(2) Internal oscillation mode register (RCM)
Remarks 1. MCM0: Bit 0 of the main clock mode register (MCM)
Notes 1. The main clock mode register (MCM) is used to set the CPU clock (high-speed system clock/internal
The fastest instruction can be executed in 2 clocks of the CPU clock in the 78K0/KD1+.
relationship between the CPU clock (f
This register sets the operation mode of internal oscillator.
This register is valid when “Can be stopped by software” is set for internal oscillator by the option byte, and the
high-speed system clock or subsystem clock is selected as the CPU clock. If “Cannot be stopped” is selected for
internal oscillator by the option byte, settings for this register are invalid.
RCM can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
f
f
f
f
f
f
Address: FFA0H
X
X
X
X
X
XT
/2
/2
/2
/2
CPU Clock (f
/2
Symbol
2
3
4
RCM
2.
Table 5-2. Relationship Between CPU Clock and Minimum Instruction Execution Time
2. f
3. f
4. f
5. f
oscillation clock) (see Figure 5-4).
Setting is prohibited for the (A1) grade products.
Caution Make sure that the bit 1 (MCS) of the main clock mode register (MCM) is 1 before
X
R
XP
XT
: Main system clock oscillation frequency (high-speed system clock oscillation frequency or
: Internal oscillation clock oscillation frequency
CPU
: High-speed system clock oscillation frequency
: Subsystem clock oscillation frequency
RSTOP
internal oscillation clock oscillation frequency)
)
7
0
0
1
After reset: 00H
Figure 5-3. Format of Internal Oscillation Mode Register (RCM)
0.2
0.4
0.8
1.6
3.2
At 10 MHz Operation
setting RSTOP.
µ
µ
µ
µ
µ
Internal oscillator oscillating
Internal oscillator stopped
s
s
s
s
s
High-Speed System Clock
6
0
R/W
CHAPTER 5 CLOCK GENERATOR
CPU
) and minimum instruction execution time is as shown in the Table 5-2.
User’s Manual U16962EJ3V0UD
−
5
0
0.125
0.25
0.5
1.0
2.0
At 16 MHz Operation
Minimum Instruction Execution Time: 2/f
µ
µ
µ
µ
s
s
s
µ
s
Internal oscillator oscillating/stopped
s
Note 1
4
0
8.3
16.6
Setting prohibited
Setting prohibited
Setting prohibited
3
0
Internal Oscillation
At 240 kHz (TYP.)
µ
s (TYP.)
µ
Operation
s (TYP.)
Clock
−
Note 1
2
0
Note 2
CPU
122.1
1
0
Subsystem Clock
At 32.768 kHz
µ
Operation
s
−
−
−
−
−
Therefore, the
RSTOP
<0>
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