38K2 Datasheet, PDF (97/151 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

38K2 Group
XIN XOUT
Rd (Note)
CIN COUT
Note : Insert a damping resistor if required.
The resistance will vary depending on the oscillator
and the oscillation drive capacity setting.
Use the value recommended by the maker of the
oscillator.
Also, if the oscillator manufacturer's data sheet
specifies that a feedback resistor be added external
to the chip though a feedback resistor exists on-chip,
insert a feedback resistor between XIN and XOUT
following the instruction.
Fig. 141 Ceramic resonator or quartz-crystal oscilltor circuit
b7
b0
MISRG
(MISRG: address 0FFB16)
Oscillation stabilizing time set after STP instruction
released bit
0: Automatically set “0116” to Timer 1,
“FF16” to Prescaler 12
1: Automatically set nothing
Not used (indefinite at read)
Fig. 143 Structure of MISRG
XIN
XOUT
Open
External oscillation circuit
VCC
VSS
Fig. 142 External clock input circuit
XIN
XOUT
fvco
PLL
USB clock selection bit
fUSB
1/4 1/6 1/8
USB clock division
ration selection bits
fSYN
System clock selection bit
fsio
fAD
1/2 1/2 1/2 1/2
Prescaler 12
1/1 1/2 1/4 1/8
FF16
System clock division
ration selection bits
Timer 1
Reset or STP
0116 ^instruction
Timing φ (internal clock)
QS
SQ
R
STP instruction
WIT
instruction
R
Reset
Interrupt disable flag l
Interrupt request
Fig. 144 System clock generating circuit block diagram (single-chip mode)
QS
Reset
R STP instruction
Rev.3.00 Oct 15, 2006 page 97 of 147
REJ03B0193-0300