7 ClOCK GeneRaTOR (ClG)
S1C17624/604/622/602/621 TeChniCal Manual
Seiko epson Corporation
7-1
Clock Generator (CLG)
7
ClG Module Overview
7.1
The clock generator (CLG) controls the internal oscillators and the system clocks to be supplied to the S1C17 Core,
on-chip peripheral modules, and external devices.
The features of the CLG module are listed below.
• Generates the operating clocks with the built-in oscillators.
- IOSC oscillator circuit: 2.7 MHz (typ.)
- OSC3 oscillator circuit: 8.2 MHz (max.) crystal or ceramic oscillator circuit
Supports an external clock input.
- OSC1 oscillator circuit: 32.768 kHz (typ.) crystal oscillator circuit
• Switches the system clock. The system clock source can be selected from IOSC, OSC3, and OSC1 via software.
• Generates the CPU core clock (CCLK) and controls the clock supply to the core block. The CCLK frequency can
be selected from system clock
×
1/1, 1/2, 1/4, and 1/8.
• Controls the clock supply to the peripheral modules.
• Turns the clocks on and off according to the CPU operating status (RUN, HALT, or SLEEP).
• Controls two clock outputs to external devices.
Figure 7.1.1 shows the clock system and CLG module configuration.
CCLK
HSCLK
HSCLK
SYSCLK
OSC1
OSC3
OSC1
OSC1
IOSC
FOUT1
output circuit
OSC3
oscillator
(8.2 MHz)
IOSC
oscillator
(2.7 MHz)
OSC1
oscillator
(32.768 kHz)
Clock gear
(1/1–1/8)
Gate
S1C17 Core
CT, SWT, WDT
RTC
*
OSC3
OSC4
FOUT1
FOUTH
output circuit
FOUTH
OSC1
OSC2
HALT
ClG
T16, T8F, T16E,
UART, SPI, I2CM,
I2CS, P, MISC,
VD1, SVD, REMC,
ADC10, ITC
PCLK
256 Hz
Gate
Gate
LCD, SVD, RFC,
T8OSC1, T16A2
*
Divider
Divider
Wait circuit
Wait circuit
Noise filter
RESET
NMI
Noise filter
Wait circuit
To internal circuits
To S1C17 Core
*
S1C17624/604 only
1.1 CLG Module Configuration
Figure 7.
To reduce current consumption, control the clock in conjunction with processing and use HALT and SLEEP modes.
For more information on reducing current consumption, see “Power Saving” in the appendix chapter.