RL78/G1H CHAPTER 6 CLOCK GENERATOR
R01UH0575EJ0120 Rev. 1.20 Page 115 of 920
Dec 22, 2016
6.3.8 High-speed on-chip oscillator frequency select register (HOCODIV)
The frequency of the high-speed on-chip oscillator which is set by an option byte (000C2H) can be changed by
using high-speed on-chip oscillator frequency select register (HOCODIV).
The HOCODIV register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to the value set by FRQSEL2 to FRQSEL0 of the option byte
(000C2H).
Figure 6 - 12 Format of High-speed on-chip oscillator frequency select register (HOCODIV)
Caution 1. Set the HOCODIV register within the operable voltage range of the flash operation mode set in the
option byte (000C2H) before and after the frequency change.
Caution 2. Set the HOCODIV register with the high-speed on-chip oscillator clock (f
IH) selected as the
CPU/peripheral hardware clock (f
CLK).
Caution 3. After the frequency is changed with the HOCODIV register, the frequency is switched after the
following transition time has elapsed.
• Operation for up to three clocks at the pre-change frequency
• CPU/peripheral hardware clock wait at the post-change frequency for up to three clocks
Address: F00A8H After reset: the value set by FRQSEL2 to FRQSEL0 of the option byte (000C2H) R/W
Symbol76543210
HOCODIV 0 0 0 0 0 HOCODIV2 HOCODIV1 HOCODIV0
HOCODIV2 HOCODIV1 HOCODIV0
Selection of high-speed on-chip oscillator clock frequency
FRQSEL3 = 0 FRQSEL3 = 1
000f
IH = 24 MHz fIH = 32 MHz
001f
IH = 12 MHz fIH = 16 MHz
010f
IH = 6 MHz fIH = 8 MHz
011f
IH = 3 MHz fIH = 4 MHz
1 0 0 Setting prohibited f
IH = 2 MHz
1 0 1 Setting prohibited f
IH = 1 MHz
Other than above Setting prohibited
Value of option byte (000C2H)
Flash operation mode Operating frequency range Operating voltage range
CMODE0
0 LS (low-speed main) mode 1 MHz to 8 MHz 1.8 V to 3.6 V
1 HS (high-speed main) mode 1 MHz to 16 MHz 2.4 V to 3.6 V
1 MHz to 32 MHz 2.7 V to 3.6 V
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