Cpu Clock And Peripheral Function Clock; Cpu Clock; Peripheral Function Clock(F 1Sio 2Sio 8Sio 32Sio Ad ) - Renesas M16C FAMILY series Hardware Manual

M 1 6 C 2 / 8 G o r u p ( M 1 6 C

7.5 CPU Clock and Peripheral Function Clock

The CPU clock is used to operate the CPU and peripheral function clocks are used to operate the periph-
eral functions.

7.5.1 CPU Clock

This is the operating clock 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 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 "00
After reset, the on-chip oscillator clock divided by 16 provides the CPU clock.
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).
7.5.2 Peripheral Function Clock(f
These are operating clocks for the peripheral functions.
Of these, fi (i = 1, 2, 8, 32) and fi
by dividing them by i. The clock fi is used for Timer A, Timer B, SI/O3 and SI/O4 while fiSIO is used for
UART0 to UART2. Additionally, the f1 and f2 clocks are also used for dead time timer, Timer S, multi-
2
master I C bus.
The f clock is produced from the main clock, PLL clock or on-chip oscillator clock, and is used for the A/
AD
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, fi and f
SIO AD
The f clock is produced from the sub clock, and is used for timers A and B. This clock can only be used
C32
when the sub clock is on.
R e . v 2 0 . 0 J a . n 3 , 1 2 0 0 7
R E J 0 9 B 0 0 4 7 0 - 2 0 0
2 / , 8 M 1 6 C 2 / 8 ) B
" (undivided).
2
1
are derived from the main clock, PLL clock or on-chip oscillator clock
SIO
clocks are turned off.
page 55
f o 3 8 5
, f , f , f , f , f
2 8 32 1SIO 2SIO
7. Clock Generation Circuit
, f , f , f , f
8SIO 32SIO AD
)
C32