CMX878 View Datasheet(PDF) - CML Microsystems Plc
Part Name
Description
MFG CO.
'CMX878' PDF : 63 Pages View PDF
Line Powered Modem plus DAA
CMX878
Tx Mode Register b8-7: Tx Guard tone (QAM, DPSK modes)
These 2 bits select the guard tone to be transmitted together with highband QAM or DPSK.
Set both bits to 0 in FSK modes.
b8
b7
1
1
Tx 550Hz guard tone
1
0
Tx 1800Hz guard tone
0
x
No Tx guard tone
Tx Mode Register b6-5: Tx Scrambler (QAM, DPSK modes)
These 2 bits control the operation of the Tx scrambler used in QAM and DPSK modes.
Set both bits to 0 in FSK modes.
b6
b5
1
1
Scrambler enabled, 64 ones detect circuit enabled (normal use)
1
0
Scrambler enabled, 64 ones detect circuit disabled
0
x
Scrambler disabled
Tx Mode Register b4-3: Tx Data Format (QAM, DPSK, FSK modes)
These two bits select Synchronous or Start-stop mode and the addition of a parity bit to
transmitted characters in Start-stop mode.
b4
b3
1
1
Synchronous mode
1
0
Start-stop mode, no parity
0
1
Start-stop mode, even parity bit added to data bits
0
0
Start-stop mode, odd parity bit added to data bits
Tx Mode Register b2-0: Tx Data and Stop bits (QAM, DPSK, FSK Start-Stop modes)
In Start-stop mode these three bits select the number of Tx data and stop bits.
b2 b1 b0
1
1
1 8 data bits, 2 stop bits
1
1
0 8 data bits, 1 stop bit
1
0
1 7 data bits, 2 stop bits
1
0
0 7 data bits, 1 stop bit
0
1
1 6 data bits, 2 stop bits
0
1
0 6 data bits, 1 stop bit
0
0
1 5 data bits, 2 stop bits
0
0
0 5 data bits, 1 stop bit
Tx Mode Register b2-0: Tx Data source (QAM, DPSK, FSK Synchronous mode)
In Synchronous mode (b4-3 = 11) these three bits select the source of the data fed to the Tx
FSK or QAM/DPSK scrambler and modulator.
b2 b1 b0
1
x
x Data bytes from Tx Data Buffer
0
1
1 Continuous 1s
0
1
0 Continuous 0s
0
0
x Continuous V.22bis handshake S1 pattern dibits ’00,11’ in DPSK and
QAM modes, continuous alternating 1s and 0s in all other modes.
© 2002 Consumer Microcircuits Limited
36
D/878/2
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