SM3 Datasheet, PDF (27/36 Pages) Connor-Winfield Corporation – ULTRA MINIATURE STRATUM 3 MODULE

Application Notes continued
Table 5
Register
0x25
0x26
0x27
0x11
Hold Over History access and Control Registers
Register Name
History_Policy
History_Cmd
Holdover_Time
DPLL_Status
Description
Sets policy for Hold Over history accumulation: “Rebuild” or “Continue”
Save, restore, and flush commands for Hold Over history
Indicates the time since entering the Hold Over state
Bits 3 and 4: Hold Over Available” and “Hold Over Build Complete”
Figure 9
Hold Over History and Status States
Reference Switch
Flush
Reference Switch
Acquire Reference
Hold Control = 0
Hold Available = 0
Reference Lock
Flush
Build History
Hold Control = 0
Hold Available = 0
History Build Complete
Flush
Reference Lock
(with "Continue" set)
Reference Switch
Reference Switch
History Restored from backup,
re-start the building procedure.
Locked, History
Complete
Hold Control =1
Hold Available = 1
Reference Switch
Acquire Reference
Hold Control = 0
Hold Available = 1
Reference Lock
(with "Rebuild" set)
Build History
Hold Control = 0
Hold Available = 1
History Build
Complete,
Replace Active
Hold Over History
Data Sheet #: TM052 Page 27 of 36 Rev: 03 Date: 11/07/08
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