FSK Modem and DTMF Codec
CMX865
Rx Mode Register b5-3: Rx USART Setting (Rx Modem Modes)
These three bits select the Rx USART operating mode.
b5
b4
b3
1
1
1
0
1
1
0
x
1
0
x
x
Rx Synchronous mode
Rx Start-stop mode
Reserved
Rx USART function disabled
Rx Mode Register b2-0: Rx Data Bits and Parity (Rx Start-Stop Modes)
In Rx Start-stop mode these three bits select the number of data bits (plus any parity bit) in each
received character. These bits are ignored in Rx Synchronous mode.
b2
b1
b0
1
1
1
1
0
0
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
8 data bits + parity
8 data bits
7 data bits + parity
7 data bits
6 data bits + parity
6 data bits
5 data bits + parity
5 data bits
Rx Mode Register b2-0: Tones Detect Mode
In Tones Detect Mode (Rx Mode Register b14-12 = 001) b8-3 should be set to 000000. These
three bits select the detector type.
b2
b1
b0
1
0
0
0
0
0
1
1
0
0
0
1
0
1
0
Programmable Tone Pair Detect
Call Progress Detect
2100Hz, 2225Hz Answer Tone Detect
DTMF Detect
Disabled
© 2005 CML Microsystems Plc
24
D/865/3
CMLMICRO [ CML MICROCIRCUITS ]
