Renesas R8C series

R8C/1A Group, R8C/1B Group 10. Clock Generation Circuit
Rev.1.30 Dec 08, 2006 Page 64 of 315
REJ09B0252-0130
Figure 10.6 Registers HRA1 and HRA2
High-Speed On-Chip Oscillator Control Register 1
(1)
Symbol Address After Reset
HRA1
0021h
When Shipping
RW
NOTE :
1.
2. Adjust the HRA1 register so that the frequency of the high-speed on-chip oscillator w ill be the maximum value or
less of the system clock.
b7 b6 b5 b4 b3 b2 b1 b0
Set the PRC0 bit in the PRCR register to 1 (w rite enable) before rew riting the HRA1 register.
RW
Function
The frequency of the high-speed on-chip oscillator is adjusted w ith bits 0 to 7.
(2)
High-speed on-chip oscillator frequency = 8 MHz
(HRA1 register = value w hen shipping ; fRING-fast mode 0)
Setting the HRA1 register to a low er value (minimum value: 00h), results in a higher
frequency.
Setting the HRA1 register to a higher value (maximum value: FFh), results in a low er
frequency.
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 the HRA2 register.
2.
3.
4.
5. Set the HRA20 and HRA21 bits so that the frequency of the high-speed on-chip oscillator w ill be the maximum value
or less of the system clock.
b7 b6 b5 b4 b3 b2 b1 b0
000
HRA20 RW
HRA21 RW
High-speed on-chip oscillator mode
select bits
(5)
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.
High-speed on-chip oscillator frequency = 8 MHz (HRA1 register = value w hen shipping)
If fRING-fast mode 0 is sw itched to fRING-fast mode 1, the frequency is multiplied by 1.5.
If fRING-fast mode 0 is sw itched to fRING-fast mode 2, the frequency is multiplied by 0.5.
—
(b4-b2)
Reserved bits Set to 0.
RW
—
(b7-b5)
—
Nothing is assigned. If necessary, set to 0.
When read, the content is 0.