4513_03 Datasheet, PDF (167/210 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.10 Oscillation circuit
2.10.2 Oscillation operation
System clock is supplied to CPU and peripheral device as the standard clock for the microcomputer
operation. For the 4513/4514 Group, the clock (f(XIN)), (f(XIN)/2) which is supplied from the oscillation
circuit is selected with the register MR.
Figure 2.10.2 shows the structure of the clock control circuit.
XIN
XOUT
Oscillation
circuit
Division circuit
(divided by 2)
MR3
1
0
Internal clock
generation circuit
(divided by 3)
System clock
Instruction clock
Counter
POF instruction
R
Q
S
Wait time (Note) _Software
control circuit
start signal
RESET
Key-on wake up control register
K00,K01,K02,K03
Falling detected
Multi-
plexer
Ports P00, P01
Ports P02, P03
Ports P10, P11
Ports P12, P13
I12
0
1
“H” level
I22
“L” level
0
1
“H” level
P30/INT0
P31/INT1
Note: The wait time control circuit is used to generate the time required to stabilize the f(XIN) oscillation.
Fig. 2.10.2 Structure of clock control circuit
2.10.3 Notes on use
(1) Value of a part connected to an oscillator
Values of a capacitor and a resistor of the oscillation circuit depend on the connected oscillator and
the board. Accordingly, consult the oscillator manufacturer for values of each part connected the
oscillator.
2-64
4513/4514 Group User’s Manual