CMX878 View Datasheet(PDF) - CML Microsystems Plc
Part Name
Description
MFG CO.
'CMX878' PDF : 63 Pages View PDF
Line Powered Modem plus DAA
CMX878
1.5.12.1 General Reset Command
General Reset Command (no data)
C-BUS address $01
This command resets the device and clears all bits of the General Control, Transmit Mode, Receive
Mode, Line Control, DAC Mode and ADC Mode Registers and bits 15 and 13-0 of the Status Register. It
does not affect the Standby Supply Registers.
1.5.12.2 Configuration Register
Configuration Register: 16-bit read & write C-BUS addresses: write $F0 ; read $F1
This is a ‘Standby Supply Register’.
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bits 5-15
Writing 1 enables Detection of Line Reversal Event
Writing 1 enables Detection of Start of Ring Event
Writing 1 enables Detection of End of Ring Burst Event
Set this bit to 0
Regulated Supply Enable
1 powers the Regulated Supply.
0 de-powers up the Regulated Supply.
Note that this bit can get set to 1 by events other than a C-BUS write – see
below.
General Purpose Bits 5-15
Whenever a C-BUS ‘write’ is made to this register, its contents will be deemed VALID and Line/Wakeup
Event Register bit 5 will be set to 1. Any loss of the Standby Supply will invalidate the contents of this
register and it will need to be (re-) programmed; read Line/Wakeup Event Register bit 5 to check if this is
necessary.
Bits 0-2. Depending on which type of Line Reversal or Ring event is to be detected, set one of these bits
to logic 1. If it is necessary to distinguish between a Line Reversal and a Ring then set bit 0 to 1; the
microcontroller will be alerted to the first RT pin edge and can then monitor any further activity by reading
the RD and RT bits from the Line/Wakeup Event Register.
Bit 3. Set this bit to 0.
When one of the above Detection Events occurs, bit 4 will be set to 1 powering the Regulated Supply and
the microcontroller; also the Status Register bit 14 will be set to 1.
Bit 4. When this bit is set to 0* the Regulated Supply will be de-powered and only the circuits powered by
the Standby Supply will remain active (Ring, Line Reversal Detectors, WAKE input, Standby Supply
Registers). Both the microcontroller and the C-BUS will be deactivated and this state will remain until a
Wake Event occurs. The contents of all non-Standby registers will be lost.
This bit should be set to 1 when the Regulated Supply is to remain in its powered state.
This bit is also gets set to 1 by:
An Event – any of Line/Wakeup Event Register bits 0-3 going to 1 (as caused by a Line
Reversal, Ring or WAKE pin Event),
A Power-on-Reset – the Line/Wakeup Event Register bit 5 goes to 0 (when the contents of the
Standby Registers are NOT VALID due to a previous loss of the Standby Supply).
*Note: Because an event indicated by the Line/Wakeup Event Register can set this bit, the Line/Wakeup
Event Register must always be read (clearing it) before de-powering the Regulated Supply with Bit 4.
© 2002 Consumer Microcircuits Limited
29
D/878/2
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