
DS21Q55 Quad T1/E1/J1 Transceiver
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12.
The device contains four counters that are used to accumulate line-coding errors, path errors, and
synchronization errors. Counter update options include one-second boundaries, 42ms (T1 mode only),
62ms (E1 mode only), or manual. See
Error-Counter Configuration Register (ERCNT)
. When updated
automatically, the user can use the interrupt from the timer to determine when to read these registers. All
four counters saturate at their respective maximum counts, and they do not roll over. Note: Only the line-
code violation count register has the potential to overflow, but the bit error would have to exceed 10E-2
before this would occur.
Register Name:
ERCNT
Register Description:
Error-Counter Configuration Register
Register Address:
41h
Bit #
7
6
5
4
Name
—
MECU
ECUS
EAMS
VCRFS
Default
0
0
0
0
Bit 0/T1 Line-Code Violation Count Register Function Select (LCVCRF)
0 = do not count excessive 0s
1 = count excessive 0s
Bit 1/Multiframe Out-of-Sync Count Register Function Select (MOSCRF)
0 = count errors in the framing bit position
1 = count the number of multiframes out-of-sync
Bit 2/PCVCR Fs-Bit Error-Report Enable (FSBE)
0 = do not report bit errors in Fs-bit position; only Ft-bit position
1 = report bit errors in Fs-bit position as well as Ft-bit position
Bit 3/E1 Line-Code Violation Count Register Function Select (VCRFS)
0 = count bipolar violations (BPVs)
1 = count code violations (CVs)
Bit 4/Error-Accumulation Mode Select (EAMS)
0 = ERCNT.5 determines accumulation time
1 = ERCNT.6 determines accumulation time
Bit 5/Error-Counter Update Select (ECUS)
T1 Mode:
0 = update error counters once a second
1 = update error counters every 42ms (333 frames)
E1 Mode:
0 = update error counters once a second
1 = update error counters every 62.5ms (500 frames)
Bit 6/Manual Error-Counter Update (MECU).
When enabled by ERCNT.4, the changing of this bit from a 0 to
a 1 allows the next clock cycle to load the error-counter registers with the latest counts and reset the counters. The
user must wait a minimum of 1.5 RCLK clock periods before reading the error count registers to allow for proper
update.
Bit 7/Unused, must be set to 0 for proper operation
ERROR COUNT REGISTERS
3
2
1
0
FSBE
0
MOSCRF LCVCRF
0
0
0