Low-Speed (Osc1) Oscillation Circuit; Configuration Of Low-Speed (Osc1) Oscillation Circuit; I/O Pins Of Low-Speed (Osc1) Oscillation Circuit - Epson CMOS 32-Bit Single Chip Microcomputer S1C33L03 Technical Manual

III-6 LOW-SPEED (OSC1) OSCILLATION CIRCUIT

Configuration of Low-Speed (OSC1) Oscillation Circuit

The Peripheral Block has a built-in low-speed (OSC1) oscillation circuit.
The low-speed (OSC1) oscillation circuit generates a 32.768-kHz (Typ.) subclock.
The OSC1 clock output by this circuit is delivered to the CLG (clock generator) in the Core Block and is used as
the source clock for the clock timer. It can also be used as a sub-clock for the low-speed (low-power) operation of
the CPU and peripheral circuits (switchable in a program).
Figure 6.1 shows the configuration of the clock system.
Oscillation
ON/OFF
OSC1 Low-speed (OSC1)
OSC2 oscillation circuit
I/O port
FOSC1
(P14)
The CPU operating clock can be switched to the output (OSC1 clock) of the low-speed (OSC1) oscillation circuit
in a program. Furthermore, the oscillation circuit can be stopped in a program.
If the OSC3 clock is unnecessary such as when performing clock processing only, set the OSC1 clock for operation
of the CPU/peripheral circuits and turn off the high-speed (OSC3) oscillation circuit in order to reduce current
consumption.
The low-speed (OSC1) oscillation circuit does not stop in SLEEP mode.
For the control method when using the OSC1 clock for the operating clock of the peripheral circuits, refer to
"Prescaler".

I/O Pins of Low-Speed (OSC1) Oscillation Circuit

Table 6.1 lists the I/O pins of the low-speed (OSC1) oscillation circuit.
Pin name I/O
OSC1 I
OSC2 O
P14/FOSC1/DCLK I/O I/O port / Low-speed (OSC1) oscillation clock output / DCLK signal output
S1C33L03 FUNCTION PART
III PERIPHERAL BLOCK: LOW-SPEED (OSC1) OSCILLATION CIRCUIT
CLG
SOSC1
OSC3/PLL
PF1ON
Figure 6.1 Configuration of Clock System
Table 6.1 I/O Pins of Low-Speed (OSC1) Oscillation Circuit
Low-speed (OSC1) oscillation input pin
Crystal oscillation or external clock input
Low-speed (OSC1) oscillation output pin
Crystal oscillation (open when external clock is used)
CLKCHG
Clock
clock
switch
Prescaler
Clock timer
Function
EPSON
To CPU
and BCU
To peripheral
circuits
B-III-6-1
A-1
B-III
OSC1