upd70f3422gj-gae-qs-ax Renesas Electronics Corporation., upd70f3422gj-gae-qs-ax Datasheet - Page 186

• Manufacturer Part Number: upd70f3422gj-gae-qs-ax
• Description: 32-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

Chapter 4
186
Main oscillator
Ring oscillator
Sub oscillator
stopped
stopped
stopped
Caution
(3)
Since CLMCS.CMRT = 1 is synchronized with the ring oscillator any change of
this bit has to be maintained for at least 65 ring oscillator periods T
f
this bit is changed again.
Proceed as follows to start the sub oscillator clock monitor:
1. After reset enable sub oscillator clock monitor:
2. Make sure the sub oscillator is stable.
3. Start sub oscillator clock monitor after reset and after power save mode
4. Wait for 65 ring oscillator periods T
5. Clear CLMCS.CMRT:
6. Before CMRT should be set to 1 again, wait for 65 ring oscillator periods
Note that the minimum ring oscillator frequency min(f
to be taken into account for the wait time in steps (3) and (5).
The sub oscillator clock monitor is sometimes already started by setting
CLMS.CLMES = 1, i.e. without CLMCS.CMRT = 1.
In these cases it would not be required to start the sub oscillator by setting
CLMCS.CMRT = 1 additionally.
Since it is unpredictable whether the clock monitor has already started after
CLMS.CLMES = 1 the procedure described above should be followed in any
case.
Operation during and after power save modes
If the main oscillator is stopped, its clock monitor changes to stand-by. When
the main oscillator is restarted after power save mode release, the main
oscillator clock monitor restarts automatically.
If the sub oscillator is stopped, its clock monitor stops.
When the sub oscillator is restarted after power save mode release, the sub
oscillator clock monitor does not start automatically.
Software must ensure that the sub oscillator stabilization time has elapsed and
then start the monitor by setting CLMCS.CMRT to 1.
If the ring oscillator is stopped, both clock monitors’ operation is suspended.
Their operation is automatically resumed as soon as the ring oscillator is
restarted.
Preliminary User’s Manual U17566EE1V2UM00
ROSC
wake-up:
T
ROSC
PRCMDCM = FF
CLMS.CLMES = 1enable sub oscillator clock monitor
CLMCS.CMRT = 1
wait (65 x max(T
CLMCS.CMRT = 0
wait (65 x max(T
to become effective. Therefore a wait period has to be assured before
:
ROSC
ROSC
H
permit write to CLMS
))
))
ROSC
before resetting CMRT:
ROSC
) (max(T
Clock Generator
ROSC
ROSC
)) has
= 1/