Renesas rl78 User Manual
RL78/G1A
CHAPTER 5 CLOCK GENERATOR
R01UH0305EJ0200 Rev.2.00
143
Jul 04, 2013
Remark f
X
:
X1 clock oscillation frequency
f
IH
:
High-speed on-chip oscillator clock frequency
f
EX
:
External main system clock frequency
f
MX
:
High-speed system clock frequency
f
MAIN
: Main system clock frequency
f
XT
:
XT1 clock oscillation frequency
f
EXS
: External subsystem clock frequency
f
SUB
: Subsystem clock frequency
f
CLK
: CPU/peripheral hardware clock frequency
f
IL
:
Low-speed on-chip oscillator clock frequency
5.3 Registers Controlling Clock Generator
The following nine registers are used to control the clock generator.
• Clock operation mode control register (CMC)
• System clock control register (CKC)
• Clock operation status control register (CSC)
• Oscillation stabilization time counter status register (OSTC)
• Oscillation stabilization time select register (OSTS)
• Peripheral enable register 0 (PER0)
• Subsystem clock supply mode control register (OSMC)
• High-speed on-chip oscillator frequency select register (HOCODIV)
• High-speed on-chip oscillator trimming register (HIOTRM)
Caution Which registers and bits are included depends on the product. Be sure to set registers and bits that
are not mounted in a product to their initial values.
5.3.1 Clock operation mode control register (CMC)
This register is used to set the operation mode of the X1/P121, X2/EXCLK/P122, XT1/P123, and XT2/EXCLKS/P124
pins, and to select a gain of the oscillator.
The CMC register can be written only once by an 8-bit memory manipulation instruction after reset release. This
register can be read by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
<R>
<R>