Rainbow Electronics DS31256 - Manual (Page 59)

DS31256
59 of 181
Figure 6-6. Receive V.54 State Machine
VRST = 1
VLB = 0
VTO = 0
SLBP = 0
Search for
Loop Up
Pattern for
32 VCLKs
Reset 4 second timer;
wait for Loss of Sync or
All 1s (64 in a Row)
or for the 4 second
timer to expire
Search for
Loop Down
Pattern
VLB = 1
Sync = 0
VLB = 0
Sync = 1
VTO = 1
Sync = 0
Sync = 0 or
4 Second Timer
Has Expired
Sync = 1
All Ones
Time Out (VTO)
Loopback (VLB);
both in RP[n]CR
V.54 State
Machine
CLK
Data
VRST (in RP[n]CR)
v54sm
All Ones
SYSCLK
Sysclk is used only to time
a 4 second timer. It is run into
a 2E27 counter which provides
a 4.03 second time out with a
33MHz clock and a 5.37 second
time out with a 25MHz clock
wait for Loss of Sync or
All 1s (64 in a Row)
Sync = 0
Change of
State in Status
(SLBP); in SV54
SLBP = 1
SLBP = 1