DS80CH11 Datasheet, PDF (70/88 Pages) Dallas Semiconductor – System Energy Manager

DS80CH11
Table 12–3 is a summary of the bits relating to Slow Clock Mode and its operation.
ENTERING / EXITING SLOW CLOCK MODE Figure 12–1
ENTER SLOW CLOCK MODE
EXITING SLOW CLOCK MODE
ALLOW
N
HARDWARE TO CAUSE
A SWITCHBACK
?
Y
SET SWB=1
SOFTWARE DECIDES
TO EXIT
SWB=1 AND EXTERNAL
ACTIVITY OCCURS
CD1, CD0 = 01 FOR 4
HARDWARE AUTOMATICALLY
SWITCHES CD1, CD0
CHECK
STATUS=0
?
Y
N
CHECK AND CLEAR
IMPENDING ACTIVITY
INVOKE SLOW CLOCK MODE
CLOCK SPEED = 64 OR 1024
CD1, CD0=10 FOR 64
CD1, CD0=11 FOR 1024
OPERATE
N
WITHOUT CRYSTAL
?
Y
DONE
XT/RG=0
DISABLE CRYSTAL?
N
(NO FAST SWITCH
TO XTAL)
Y
DONE
XTOFF = 1
LOWEST POWER OPERATING STATE
011200 70/88
CHECK
STATUS=0
?
Y
N
DONE
XTOFF = 1
?
Y
XTOFF = 0
N
XT/RG=1
DONE
XTUP = 1
N
?
Y
XT/RG=1
DONE