
HYUNDAI MicroElectronics
16
2.3. CLOCK GENERATION CIRCUIT
The clock generation circuit of GMS81508/16 consists of oscillation circuit, prescaler, Basic Interval
Timer.
The source clock of peripherals is provided by 11-bit prescaler.
OSC
Circuit
Clock Pulse Generator
Prescaler
MUX
B.I.T.(8)
W.D.T.(6)
Comparator
WDTR
0
1
2
3
4
5
6
7
Internal System Clock
IFBIT
IFWDT
BTCL
ENPCK
WDTCL
To RESET
Circuit
Internal Data Bus
8
6
6
CKCTLR
6
2.3.1. Oscillation Circuit
The clock signal incoming from crystal oscillator or ceramic resonator via Xin and Xout or from
external clock via Xin is supplied to Clock Pulse Generator and Prescaler.
The internal system clock for CPU is made by Clock Pulse Generator, and several peripheral clock
is divided by prescaler.
The clock generation circuit of crystal oscillator or ceramic resonator is shown in below.
Crystal Oscillator or Ceramic Resonator
External clock
In STOP Mode, The oscillation is stopped,
Xin pin goes to "L" level status, and Xout pin goes to "H" level state.
Xin
Cin
GND
Cout
Xout
Xin
External
Clock
Open
Xout