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FUJITSU F2MCTM-16LX User Manual

Page 112

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CHAPTER 5 CLOCKS

Oscillation clock generation circuit

This circuit generates an oscillation clock (HCLK) by connecting an oscillator or inputting an external

clock to the high-speed oscillation pins.

Sub-clock generation circuit

This circuit generates a sub clock (SCLK) by connecting an oscillator or inputting an external clock to the

low-speed oscillation pins (X0A, X1A).

PLL multiplier circuit

This circuit multiplies the oscillation clock and supplies it as a PLL clock (PCLK) to the clock selector.

Clock selector

From among the main clock, five different PLL clocks and subclock, the clock selector selects the clock

that is supplied to the CPU and peripheral function.

Clock selection register (CKSCR)

The clock selection register is used to switch between the oscillation clock and PLL clock and between the

main clock and sub-clock, also used to select an oscillation stabilization wait interval and a PLL clock

multiplier.

PLL/Subclock Control Register (PSCCR)

The PLL/subclock control register is used to select multiplication ratio of the PLL (CS2 bit in this register

in addition to CS1 and CS0 bits in the CKSCR register) and to specify division ratio (1/4 or 1/2) of the

subclock.

Oscillation stabilization wait interval selector

This oscillation stabilization wait interval selector selects an oscillation stabilization wait interval for the

oscillation clock. Selection is made from among four different timebase timer outputs.