FSK Modem and DTMF Codec
CMX865
5.10.4 Receive Mode Register
Receive Mode Register: 16-bit write-only.
C-BUS address $E2
This register controls the CMX865 receive 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
0
14
13
12
11
10
9
8
0
7
0
6
0
5
4
3
2
1
0
Bit:
Rx mode =
Modem
Rx level
Start-stop/Synch
No. of bits and
parity
0
0
Rx mode =
Rx level
DTMF/Tones/Call Progress select
Set to 0000 0000 0000
Tones detect
Rx mode =
Disabled
Rx Mode Register b15: Reserved, set to 0
Rx Mode Register b14-12: Rx Mode
These three bits select the receive operating mode.
b14 b13 b12
1
1
1
1
0
0
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
Bell 103 300bps FSK
“
V.23 FSK
“
Bell 202 FSK
“
Tones detect
Receiver disabled
High band (Calling modem)
Low band (Answering modem)
1200bps
75bps
1200bps
150bps
Rx Mode Register b11-9: Rx Level
These three bits set the gain of the Rx Gain 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
© 2005 CML Microsystems Plc
23
D/865/3
CMLMICRO [ CML MICROCIRCUITS ]
