III PERIPHERAL BLOCK: LOW-SPEED (OSC1) OSCILLATION CIRCUIT

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

 

 

 

 

 

 

CLG

 

CLKCHG

 

 

 

 

 

SOSC1

 

 

 

 

 

 

 

 

 

ON/OFF

 

 

 

 

 

 

OSC3/PLL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OSC1

 

 

Low-speed (OSC1)

 

 

clock

 

 

 

Clock

 

 

To CPU

 

 

 

 

 

 

 

 

 

switch

 

 

OSC2

 

 

oscillation circuit

 

 

 

 

 

 

 

 

 

and BCU

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FOSC1

 

 

I/O port

 

 

 

 

 

 

 

 

 

 

Prescaler

 

 

To peripheral

(P14)

 

 

 

 

 

 

 

 

 

PF1ON

 

 

 

 

 

 

 

 

 

 

circuits

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Clock timer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 6.1 Configuration of Clock System

 

 

 

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.

 

 

Table 6.1 I/O Pins of Low-Speed (OSC1) Oscillation Circuit

Pin name

I/O

Function

OSC1

I

Low-speed (OSC1) oscillation input pin

 

 

Crystal oscillation or external clock input

OSC2

O

Low-speed (OSC1) oscillation output pin

 

 

Crystal oscillation (open when external clock is used)

P14/FOSC1/DCLK

I/O

I/O port / Low-speed (OSC1) oscillation clock output / DCLK signal output

S1C33210 FUNCTION PART

EPSON

B-III-6-1