Renesas M16C FAMILY Hardware Manual page 41

Under development
Preliminary specification
Specifications in this manual are tentative and subject to change.
R8C/11 Group
Oscillation stop detection register
b7 b6 b5 b4 b3 b2
0 0 0 0
Notes:
1. Set the PRC0 bit in the PRCR register to "1" (write enable) before rewriting this register.
2. The OCD2 bit is set to "1" (selecting ring oscillator clock) automatically if a main clock oscillation stop is
detected while the OCD1 to OCD0 bits are set to "11
OCD3 bit is set to "1" (main clock stop), the OCD2 bit remains unchanged when trying to write "0"
(selecting main clock).
3. The OCD3 bit is enabled when the OCD1 to OCD0 bits are set to "11
enabled). Read the OCD3 bit several times with the oscillation stop detection interrupt processing program
to determine the main clock state.
4. The OCD1 to OCD0 bits should be set to "00
stop mode and ring oscillator (main clock stops). The OCD1 to OCD0 bits should be set to "00
HR01 bit in the HR0 register is set to "1" (high-speed ring oscillator selected).
5. The OCD3 bit remains set to "0" (main clock on) if the OCD1 to OCD0 bits are set to "00
6. The CM14 bit goes to "0" (low-speed ring oscillator on) if the OCD2 bit is set to "1" (selecting ring oscillator
clock).
7. Refer to Figure 6.9 "switching clock source from low-speed ring oscillator to main clock" for the switching
procedure when the main clock re-oscillates after detecting an oscillation stop.
Figure 6.3 OCD Register
Rev.0.91 2003 Sep 08
1
b1 b0
Symbol
OCD
Bit symbol
Oscillation stop
OCD0
detection enable bit
OCD1
OCD2
System clock select bit
Clock monitor bit
OCD3
Reserved bit
(b7-b4)
page 31 of 184
Address After reset
000C
16 04
Bit name
b1 b0
0 0: The function is disabled
0 1: Avoid this setting
1 0: Avoid this setting
1 1: The function is enabled
0: Select main clock
6
1: Select ring oscillator clock
0: Main clock on
3, 5
1: Main clock off
Must set to "0"
" (oscillation stop detection function enabled). If the
2
" (oscillation stop detection function
2
" (oscillation stop detection function disabled)before entering
2
6. Clock Generating Circuit
16
Function
4
7
7
2
" when the
2
".
2
RW
RW
RW
RO
RW