CMX865 CML Microcircuits, CMX865 Datasheet - Page 18

• Manufacturer Part Number: CMX865
• Description: FSK Modem and DTMF Codec
• Manufacturer: CML Microcircuits

FSK Modem and DTMF Codec
5.10.2 General Control Register
General Control Register: 16-bit write-only.
This register controls general features of the CMX865 such as the Powersave and Loopback modes, the
IRQ mask bits and the Relay Drive output. It also allows the fixed compromise equalisers in the Tx and Rx
signal paths to be disabled if desired, and sets the internal clock dividers to use either a 11.0592 or a
12.288 MHz XTAL frequency.
All bits of this register are cleared to 0 by a General Reset command.
© 2005 CML Microsystems Plc
Bit:
General Control Register b15: Reserved, set to 0
General Control Register b14: Disconnect TXA Output
This bit allows the TXA output to be disconnected and set to high impedance.
General Control Register b13: Disconnect TXAN Output
This bit allows the TXAN output to be disconnected and set to high impedance.
General Control Register b12: Xtal Frequency
This bit should be set according to the Xtal frequency.
General Control Register b11: Analogue Loopback Test Mode
This bit controls the analogue loopback test mode. Note that in loopback test mode both Transmit
and Receive Mode Registers should be set to the same modem type and band or bit rate.
General Control Register b10: Tx and Rx Fixed Compromise Equalisers
This bit allows the Tx and Rx fixed compromise equalisers in the modem transmit and receive
filter blocks to be disabled.
General Control Register b9: Relay Drive
This bit directly controls the RDRVN output pin.
15
0
TXA
14
off
b14 = 1
b14 = 0
b13 = 1
b13 = 0
b12 = 1
b12 = 0
b11 = 1
b11 = 0
b10 = 1
b10 = 0
b9 = 1
b9 = 0
TXAN
13
off
Xtal
freq
12
LB
11
TXA output disconnected.
TXA output connected (normal modem operation).
TXAN output disconnected.
TXAN output connected (normal modem operation).
11.0592MHz
12.2880MHz
Local analogue loopback mode enabled
No loopback (normal modem operation)
Disable equalisers
Enable equalisers (1200bps modem modes)
RDRVN output pin pulled to V
RDRVN output pin pulled to V
Equ
10
Rly
drv
9
C-BUS address $E0
Pwr
8
18
Rst
7
Irqn
en
6
SS
DD
5
4
IRQ Mask Bits
3
2
1
0
CMX865
D/865/3