73K224L Datasheet, PDF (16/31 Pages) TDK Electronics – V.22bis/V.22/V.21/ Bell 212A/Bell 103 Single-Chip Modem

73K224L
V.22bis, V.22, V.21, Bell 212A, 103
Single-Chip Modem
DATA SHEET
SPECIAL REGISTER
D7
D6
D5
D4
D3
D2
D1
D0
SR
0
TXBAUD
RXUN-
0
TXD
SIGNAL
SIGNAL
0
101
CLOCK
DSCR
SOURCE
QUALITY
QUALITY
DATA
LEVEL
LEVEL
SELECT1
SELECT0
BIT NO.
NAME
DESCRIPTION
D7, D4, D0
NOT USED AT THIS TIME. Only write ZEROs to these bits.
D6
TXBAUD CLK TXBAUD clock is the transmit baud-synchronous clock that can be used to
synchronize the input of arbitrary quad/di-bit patterns. The rising edge of
TXBAUD signals the latching of a baud-worth of data internally. Synchronous
data to be entered via the TXDALT bit, CR3 bit D7, should have data transitions
that start 1/2 bit period delayed from the TXBAUD clock edges.
D5
RXUNDSCR This bit outputs the data received before going to the descrambler.
DATA
This is useful for sending special unscrambled patterns that can be used for
signaling.
D3
TXD SOURCE This bit selects the transmit data source; either the TXD pin if ZERO or the
TXDALT if this bit is a ONE. The TRANSMIT PATTERN bits D7 and D6 in CR1
override either of these sources.
D2, D1
SIGNAL
QUALITY
LEVEL
SELECT
The signal quality indicator is a logical ZERO when the signal received is
acceptable for low error rate reception. It is determined by the value of the Mean
Squared Error (MSE) calculated in the decision process when compared to a
given threshold. This threshold can be set to four levels of error rate. The SQI bit
will be low for good or average connections. As the error rate crosses the
threshold setting, the SQI bit will toggle at a 1.66 ms rate. Toggling will continue
until the error rate indicates that the data pump has lost convergence and a
retrain is required. At that point the SQI bit will be a ONE constantly. The SQI bit
and threshold selection are valid for QAM and DPSK only and indicates typical
error rate.
D2 D1
THRESHOLD VALUE
UNITS
00
10^-5
BER (default)
01
10^-6
BER
10
10^-4
BER
11
10^-3
BER
NOTE: This register is "mapped" and is accessed by setting CR2 bit D6 to a ONE and addressing CR3. This
register provides functions to the 73K224L user that are not necessary in normal communications. Bits
D7-D4 are read only, while D3-D0 are read/write. To return to normal CR3 access, CR2 bit D6 must be
returned to a ZERO.
Page: 16 of 31
© 2005, 2008 TERIDIAN Semiconductor Corporation
Rev 7.1