CMX868E2 View Datasheet(PDF) - MX-COM Inc
Part Name
Description
MFG CO.
'CMX868E2' PDF : 43 Pages View PDF
Low Power V.22bis Modem
18
CMX868 Advance Information
4.10.2 General Control Register: 16-bit write-only C-BUS address $E0
This register controls general features of the CMX868 such as the Powersave and Loopback modes, the IRQ
mask bits and the Relay Drive output. It also allows the fixed compromise equalizers 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.
Bit: 15 14 13
12
11 10
9
87
6
543210
0 0 0 Xtal freq LB Equ Rlydrv Pwr Rst Irq en
IRQ Mask Bits
General Control Register b15-13: Reserved, set to 000
General Control Register b12: Xtal frequency
This bit should be set according to the Xtal frequency.
b12 = 1
11.0592MHz
b12 = 0
12.2880MHz
General Control Register b11: Analog 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.
b11 = 1
Local analog loopback mode enabled
b11 = 0
No loopback (normal modem operation)
General Control Register b10: Tx and Rx Fixed Compromise Equalizers
This bit allows the Tx and Rx fixed compromise equalizers in the modem transmit and receive
filter blocks to be disabled.
b10 = 1
Disable equalizers
b10 = 0
Enable equalizers (600, 1200 or 2400bps modem modes)
General Control Register b9: Relay Drive
This bit directly controls the RDRV output pin.
b9 = 1
b9 = 0
RDRV output pin pulled to VSS
RDRV output pin pulled to VDD
General Control Register b8: Power-up
This bit controls the internal power supply to most of the internal circuits, including the Xtal
oscillator and VBIAS supply. Note that the General Reset command clears this bit, putting the
device into Powersave mode.
When the device is switched from Powersave mode to normal operation by setting the Powerup
bit to 1, the Reset bit should also be set to 1 and should be held at 1 for about 20ms while the
internal circuits, Xtal oscillator, and VBIAS to stabilize before starting to use the transmitter or
receiver.
Changing the Powerup bit from 0 to 1 clears all bits of the Transmit Mode and Receive Mode
Registers and clears b15 and b13-0 of the Status Register.
b8 = 1
Device powered up normally
b8 = 0
Powersave mode (all circuits except Ring Detect, RDRV and C-BUS
interface disabled)
¤2001 MX-COM, Inc.
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480205.007
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
Share Link: 
