
R8C/14 Group, R8C/15 Group 9. Clock Generation Circuit
Rev.2.10 Jan 19, 2006 Page 44 of 253
REJ09B0164-0210
Figure 9.6 HRA1 and HRA2 Registers
High-speed On-Chip Oscillator Control Register 1
(1)
Symbol Address After Reset
HRA1
0021h
When Shipping
RW
NOTES :
1. Set the PRC0 bit in the PRCR register to “1” (w rite enable) before rew riting to this register.
RW
Function
The frequency of high-speed on-chip oscillator is adjusted w ith bits 0 to 7.
High-speed on-chip oscillator frequency = 8MHz
(HRA1 register = value when shipping ; fRING-fast mode 0)
Set the value of the HRA1 register to smaller (minimum value : 00h), the frequency w ill be
higher
Set the value of the HRA1 register to larger (maximum value : FFh), the frequecny w ill be
low er
b3 b2 b1 b0b7 b6 b5 b4
High-Speed On-Chip Oscillator Control Register 2
(1)
Symbol Address After Reset
HRA2
0022h 00h
Bit Symbol Bit Name Function RW
NOTES :
1. Set the PRC0 bit in the PRCR register to “1” (w rite enable) before rew riting to this register.
2.
3.
4.
High-speed on-chip oscillator frequency = 8MHz (HRA1 register = value when shipping)
If fRING-fast mode 0 is sw itched to fRING-fast mode 1, frequency will increase 1.5 times.
If fRING-fast mode 0 is sw itched to fRING-fast mode 2, frequency will increase 0.5 times.
—
(b4-b2)
Reserved Bit Set to “0”
RW
—
(b7-b5)
—
Nothing is assigned. When write, set to “0”.
When read, its content is “0”.
HRA20 RW
HRA21 RW
High-Speed On-Chip Oscillator Mode
Select Bit
b1 b0
0 0 : fRING-fast mode 0
(2)
0 1 : fRING-fast mode 1
(3)
1 0 : fRING-fast mode 2
(4)
1 1 : Do not set
00
0
b3 b2 b1 b0b7 b6 b5 b4
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