CHAPTER 8 CLOCK GENERATOR FUNCTIONS
User’s Manual U12688EJ4V0UM00
234
8.4
PLL Lockup
Lockup time (frequency stabilization time) is the amount of time from immediately after the software STOP mode is
released after the power is turned on, until the phase locks at the proper frequency and becomes stable. The state
until this stabilization occurs is called the unlocked state and the stabilized state is called the locked state.
There is an UNLOCK flag which reflects the PLL’s frequency stabilization state, and a PRERR flag which shows
when a protection error occurs, in the system status register (SYS).
This register can be read/written in 8- or 1-bit units.
Address
FFFFF078H
7
0
SYS
6
0
5
0
4
PRERR
3
0
2
0
1
0
0
UNLOCK
After reset
0000000
×
B
Bit Position
Bit Name
Function
0
UNLOCK
Unlock Status Flag
This is an exclusive read flag and shows the PLL’s unlocked state.
As long as the lockup state is maintained, it is kept at 0, and is not initialized
when system reset occurs.
0: Indicates that the PLL is in a locked state.
1: Indicates that the PLL is not locked (in an unlocked state).
Remark
For an explanation of the PRERR flag, refer to 3.4.9 (2) System status register (SYS).
If the clock stops, the power fails, or some other factor occurs to cause the unlocked state, in control processing
which depends on software execution speed such as real-time processing, be sure to begin processing after judging
the UNLOCK flag by software immediately after operation starts, and after waiting for the clock to stabilize again.
On the other hand, for static processing such as setting of internal hardware, or initialization of register data and
memory data, it is possible to execute these without waiting for the UNLOCK flag to be reset.
The relationship between the oscillation stabilization time (the time from when the resonator starts to oscillate until
the input waveform stabilizes) when a resonator is used, and the PLL lockup time (the time until the frequency is
stabilized) is shown below.
Oscillation stabilization time < PLL lockup time
Содержание V850E/MS1 UPD703100
Страница 2: ...User s Manual U12688EJ4V0UM00 2 MEMO ...
Страница 6: ...User s Manual U12688EJ4V0UM00 6 MEMO ...
Страница 8: ...User s Manual U12688EJ4V0UM00 8 MEMO ...
Страница 12: ...User s Manual U12688EJ4V0UM00 12 MEMO ...
Страница 26: ...User s Manual U12688EJ4V0UM00 26 MEMO ...
Страница 68: ...User s Manual U12688EJ4V0UM00 68 MEMO ...
Страница 124: ...User s Manual U12688EJ4V0UM00 124 MEMO ...
Страница 198: ...User s Manual U12688EJ4V0UM00 198 MEMO ...
Страница 230: ...User s Manual U12688EJ4V0UM00 230 MEMO ...
Страница 422: ...User s Manual U12688EJ4V0UM00 422 MEMO ...