Datasheet

RL78/L12 CHAPTER 5 CLOCK GENERATOR
R01UH0330EJ0200 Rev.2.00 146
Dec 13, 2013
5.3.8 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). However, the selectable frequency depends on the
FRQSEL3 bit of the option byte (000C2H).
The HOCODIV register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to default value (undefined).
Figure 5-9. Format of High-speed On-chip Oscillator frequency select register (HOCODIV)
Address: F00A8H After reset: undefined R/W
Symbol 7 6 5 4 3 2 1 0
HOCODIV
0 0 0 0 0 HOCODIV2 HOCODIV1 HOCODIV0
HOCODIV2 HOCODIV1 HOCODIV0 High-Speed On-Chip Oscillator Clock Frequency
FRQSEL3 Bit is 0 FRQSEL3 Bit is 1
0 0 0 24 MHz Setting prohibited
0 0 1 12 MHz 16 MHz
0 1 0 6 MHz 8 MHz
0 1 1 3 MHz 4 MHz
1 0 0 Setting prohibited 2 MHz
1 0 1 Setting prohibited 1 MHz
Other than above Setting prohibited
Cautions 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.
Option Byte (000C2H)
Value
Flash Operation Mode
Operating
Frequency Range
Operating Voltage
Range
CMODE1 CMODE2
0 0 LV (low-voltage main) mode 1 to 4 MHz 1.6 to 5.5 V
1 0 LS (low-speed main) mode 1 to 8 MHz 1.8 to 5.5 V
1 1 HS (high-speed main) mode 1 to 16 MHz 2.4 to 5.5 V
1 to 32 MHz 2.7 to 5.5 V
2. Set the HOCODIV register with the high-speed on-chip oscillator clock (f
IH)
selected as the CPU/peripheral hardware clock (f
CLK).
3. After the frequency is changed with the HOCODIV register, the frequency is
switched after the following transition time has elapsed.
• Operation for three clocks at the pre-change frequency
• CPU/peripheral hardware clock wait at the post-change frequency for up to three
clocks