upd78f0148m1gka1-9eu Renesas Electronics Corporation., upd78f0148m1gka1-9eu Datasheet - Page 135

• Manufacturer Part Number: upd78f0148m1gka1-9eu
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

(3) Main clock mode register (MCM)
This register sets the CPU clock (X1 input clock/internal oscillation clock).
MCM can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Address: FFA1H
Symbol
MCM
Note Bit 1 is read-only.
Cautions 1. When internal oscillation clock is selected as the clock to be supplied to the
MCM0
MCS
7
0
0
1
0
1
After reset: 00H
2. Set MCS = 1 and MCM0 = 1 before switching subsystem clock operation to X1
Figure 6-4. Format of Main Clock Mode Register (MCM)
Operates with internal oscillation clock
Operates with X1 input clock
Internal oscillation clock
X1 input clock
CPU, the divided clock of the internal oscillator output (f
peripheral hardware (f
Operation of the peripheral hardware with internal oscillation clock cannot be
guaranteed. Therefore, when internal oscillation clock is selected as the clock
supplied to the CPU, do not use peripheral hardware. In addition, stop the
peripheral hardware before switching the clock supplied to the CPU from the X1
input clock to the internal oscillation clock. Note, however, that the following
peripheral hardware can be used when the CPU operates on the internal
oscillation clock.
• Watchdog timer
• Clock monitor
• 8-bit timer H1 when f
• Peripheral hardware selecting external clock as the clock source
input clock operation (bit 4 (CSS) of the processor clock control register (PCC)
is changed from 1 to 0).
(Except when external count clock of TM0n (n = 0, 1) is selected (TI00n valid
edge))
6
0
R/W
CHAPTER 6 CLOCK GENERATOR
Note
User’s Manual U15947EJ3V1UD
5
0
X
R
Selection of clock supplied to CPU
= 240 kHz (TYP.)).
/2
4
0
7
is selected as count clock
CPU clock status
3
0
2
0
MCS
<1>
X
) is supplied to the
MCM0
<0>
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