R5F21133DFP RENESAS [Renesas Technology Corp], R5F21133DFP Datasheet - Page 45

• Manufacturer Part Number: R5F21133DFP
• Description: 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY/R8C/Tiny SERIES
• Manufacturer: RENESAS [Renesas Technology Corp]

R8C/13 Group
Rev.1.20
REJ09B0111-0120
Figure 6.5 Examples of Main Clock Connection Circuit
The following describes the clocks generated by the clock generation circuit.
6.1 Main Clock
This clock is supplied by a main clock oscillation circuit. This clock is used as the clock source for the
CPU and peripheral function clocks. The main clock oscillator circuit is configured by connecting a
resonator between the X
tor, which is disconnected from the oscillator circuit during stop mode in order to reduce the amount of
power consumed in the chip. The main clock oscillator circuit may also be configured by feeding an
externally generated clock to the X
During reset and after reset, the main clock is turned off.
The main clock starts oscillating when the CM05 bit in the CM0 register is set to “0” (main clock on)
after setting the CM13 bit in the CM1 register to “1” (X
To use the main clock for the CPU clock, set the OCD2 bit in the OCD register to “0” (selecting main
clock) after the main clock becomes oscillating stably.
The power consumption can be reduced by setting the CM05 bit in the CM0 register to “1” (main clock
off) if the OCD2 bit is set to “1” (on-chip oscillator clock selected).
Note that if an externally generated clock is fed into the X
setting the CM05 bit to “1”. If necessary, use an external circuit to turn off the clock.
During stop mode, all clocks including the main clock are turned off. Refer to Section 6.4, “Power
Control.”
Jan 27, 2006
N O T E S:
1 . I n s e r t a d a m p i n g r e s i s t o r i f r e q u i r e d . T h e r e s i s t a n c e w i l l v a r y d e p e n d i n g o n t h e o s c i l l a t o r a n d t h e o s c i l l a t i o n d r i v e
X
( B u i l t - i n f e e d b a c k r e s i s t o r )
IN
c a p a c i t y s e t t i n g . U s e t h e v a l u e r e c o m m e n d e d b y t h e m a k e r o f t h e o s c i l l a t o r .
W h e n t h e o s c i l l a t i o n d r i v e c a p a c i t y i s s e t t o l o w , c h e c k t h a t o s c i l l a t i o n i s s t a b l e . A l s o , i f t h e o s c i l l a t o r m a n u f a c t u r e r ' s
d a t a s h e e t s p e c i f i e s t h a t a f e e d b a c k r e s i s t o r b e a d d e d e x t e r n a l t o t h e c h i p , i n s e r t a f e e d b a c k r e s i s t o r b e t w e e n X
a n d X
M i c r o c o m p u t e r
C
IN
O U T
f o l l o w i n g t h e i n s t r u c t i o n .
page 34 of 205
X
OUT
IN
R
C
and X
d
O U T
( 1 )
OUT
IN
pin. Figure 6.5 shows examples of main clock connection circuit.
pins. The main clock oscillator circuit contains a feedback resis-
IN
- X
IN
pin, the main clock cannot be turned off by
OUT
pin).
V c c
Vss
Externally derived clock
(Built-in feedback resistor)
X
I N
Microcomputer
X
O p e n
O U T
6.1 Main Clock
I N