Low Power V.22 bis Modem
CMX868
1.5.10.3 Transmit Mode Register
Transmit Mode Register: 16-bit write-only. C-BUS address $E1
This register controls the CMX868 transmit signal type and level. All bits of this register are cleared to 0
by a General Reset command, or when b7 (Reset) of the General Control Register is 1.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Bit:
Tx mode = modem
Tx level
Guard tone
Scrambler
Start-stop /
synch data
# data bits /
synch data source
Tx mode = DTMF/Tones
Tx mode = Disabled
Tx level
DTMF Twist
Set to 0000 0000 0000
DTMF or Tone select
Tx Mode Register b15-12: Tx mode
These 4 bits select the transmit operating mode.
b15 b14 b13 b12
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
V.22 bis 2400 bps QAM
High band (Answering modem)
Low band (Calling modem)
High band (Answering modem)
Low band (Calling modem)
High band (Answering modem)
Low band (Calling modem)
High band (Answering modem)
Low band (Calling modem)
High band (Answering modem)
Low band (Calling modem)
1200 bps
“
V.22/Bell 212A 1200 bps DPSK
“
V.22 600 bps DPSK
“
V.21 300 bps FSK
“
Bell 103 300 bps FSK
“
V.23 FSK
“
Bell 202 FSK
“
DTMF / Tones
Transmitter disabled
75 bps
1200 bps
150 bps
Tx Mode Register b11-9: Tx level
These 3 bits set the gain of the Tx Level Control block.
b11
b10
b9
1
1
1
1
0
0
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
0dB
-1.5dB
-3.0dB
-4.5dB
-6.0dB
-7.5dB
-9.0dB
-10.5dB
ã 2004 CML Microsystems Plc
22
D/868/9
CMLMICRO [ CML MICROCIRCUITS ]
