Low Power V.32 bis Modem
CMX869
6.3
Transmit Mode Register
Transmit Mode Register: 16-bit write-only.
C-BUS address $E1
This register controls the CMX869 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
00
Start-stop /
# data bits /
synch data synch data source
Tx mode = DTMF/Tones
Tx mode = Disabled
Tx level
0
DTMF twist
DTMF or Tone select
Set to 0000 0000 0000
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
0
0
0
0
0
0
0
0
1
1
1
0
0
0
1
1
1
1
0
0
0
0
1
0
0
1
0
0
1
1
0
0
1
1
0
0
x
1
0
x
Reserved, do not use
Reserved, do not use
V.22, V.22 bis, V.32, V.32 bis
Reserved, do not use
QAM modem
1
0
1
0
1
0
1
0
1
0
V.21 300 bps FSK
High band (Answering modem)
Low band (Calling modem)
High band (Answering modem)
Low band (Calling modem)
1200 bps
75 bps
1200 bps
150 bps
“
Bell 103 300 bps FSK
“
V.23 FSK
“
Bell 202 FSK
“
DTMF / Tones
Transmitter disabled
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
Tx Mode Register b8-7: Tx Guard tone (V.22 bis mode)
These 2 bits select the guard tone to be transmitted together with the highband (answer)
V.22 bis signal. Ignored in all other modes.
b8
b7
1
1
0
1
0
x
Tx 550Hz guard tone
Tx 1800Hz guard tone
No Tx guard tone
© 2004 CML Microsystems Plc
22
D/869/4
CMLMICRO [ CML MICROCIRCUITS ]
