M16C62P_06 Datasheet, PDF (108/421 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

M16C/62P Group (M16C/62P, M16C/62PT)
10. Clock Generation Circuit
10.2 CPU Clock and Peripheral Function Clock
Two type clocks: CPU clock to operate the CPU and peripheral function clocks to operate the peripheral functions.
10.2.1 CPU Clock and BCLK
These are operating clocks for the CPU and watchdog timer.
The clock source for the CPU clock can be chosen to be the main clock, sub clock, on-chip oscillator clock or
the PLL clock.
If the main clock or on-chip oscillator clock is selected as the clock source for the CPU clock, the selected clock
source can be divided by 1 (undivided), 2, 4, 8 or 16 to produce the CPU clock. Use the CM06 bit in CM0
register and the CM17 to CM16 bits in the CM1 register to select the divide-by-n value.
When the PLL clock is selected as the clock source for the CPU clock, the CM06 bit should be set to “0” and
the CM17 to CM16 bits to “00b” (undivided).
After reset, the main clock divided by 8 provides the CPU clock.
During memory expansion or microprocessor mode, a BCLK signal with the same frequency as the CPU clock
can be output from the BCLK pin by setting the PM07 bit in the PM0 register to “0” (output enabled).
Note that when entering stop mode from high or middle speed mode, on-chip oscillator mode or on-chip
oscillator low power dissipation mode, or when the CM05 bit in the CM0 register is set to “1” (main clock
turned off) in low-speed mode, the CM06 bit in the CM0 register is set to “1” (divide-by-8 mode).
10.2.2 Peripheral Function Clock (f1, f2, f8, f32, f1SIO, f2SIO, f8SIO, f32SIO, fAD,
fC32)
These are operating clocks for the peripheral functions.
Of these, fi (i = 1, 2, 8, 32) and fiSIO are derived from the main clock, PLL clock or on-chip oscillator clock by
dividing them by i. The clock fi is used for timers A and B, and fiSIO is used for serial I/O. The f8 and f32
clocks can be output from the CLKOUT pin.
The fAD clock is produced from the main clock, PLL clock or on-chip oscillator clock, and is used for the A/D
converter.
When the WAIT instruction is executed after setting the CM02 bit in the CM0 register to “1” (peripheral
function clock turned off during wait mode), or when the microcomputer is in low power dissipation mode, the
fi, fiSIO and fAD clocks are turned off.
The fC32 clock is produced from the sub clock, and is used for timers A and B. This clock can be used when
the sub clock is on.
10.3 Clock Output Function
During single-chip mode, the f8, f32 or fC clock can be output from the CLKOUT pin. Use the CM01 to CM00
bits in the CM0 register to select.
Rev.2.41 Jan 10, 2006 Page 93 of 390
REJ09B0185-0241