CMX878 View Datasheet(PDF) - CML Microsystems Plc
Part Name
Description
MFG CO.
'CMX878' PDF : 63 Pages View PDF
Line Powered Modem plus DAA
CMX878
Bits 5-15 are general purpose register bits which, being powered from the Standby Supply, will retain
their values even when the Regulated Supply is absent. These bits can be set by the microcontroller to
represent various operating states. Consequently if the Regulated Supply is temporarily lost (e.g. a
Central Office generated line break following an off-hook transition), when the Regulated Supply returns,
the microcontroller can read back these values to re-establish the position in its program.
1.5.12.3 Supplementary Standby Register
Supplementary Standby Register: 16-bit read and write
$F3
C-BUS addresses: write $F2 ; read
This is a ‘Standby Supply Register’ and allows for data storage even when the Regulated Supply is
removed. The bits can be used by the application for any purpose
Bit: 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
a 16-bit general purpose register – set as required
1.5.12.4 Line/Wakeup Event Register
Line/Wakeup Event Register: 16-bit read-only
C-BUS address $F4
This is a ‘Standby Supply Register’.
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 8
Bit 9
Bits 10-15
1 when a Line Reversal Event has occurred
1 when a Start of Ring Event has occurred
1 when an End of Ring Burst Event has occurred
1 when a WAKE pin Event has occurred
Reserved for future use. Currently set to 0
1 when the contents of the Standby Supply Registers are VALID.
RD. The equivalent logic level at the ring detector’s RD input
RT. The equivalent logic level at the ring detector’s RT input
1 when a Line ADC Drop-out Event has occurred
ADC comparator level (0 = ADCIN pin < ADC-REF, else 1)
Reserved for future use. Currently set to 000000
Bit 0. A ‘Line Reversal Event’ is caused by one rising edge on the RD pin.
Bit 1. A ‘Start of Ring Event’ is caused by two falling edges on the RD pin within the period that the RT
pin is low.
Bit 2. An ‘End of Ring Burst Event’ is as per the ‘Start of Ring Event’ but it does not occur until the RT
pin goes back high.
These above three Events can only occur if they were previously enabled in the Configuration Register.
Bit 3. A ‘WAKE pin Event’ is when the WAKE pin makes a 0 to 1 transition.
When one of Bits 0-3 goes to 1, bit 4 of the Configuration Register will be set to 1, powering up the
Regulated Supply and the microcontroller; also Status Register bit 14 will be set to 1.
Bit 4. Currently set to 0.
Bit 5. This bit determines the validity of the register bits which are powered from the Standby Supply.
After reading this register, the microcontroller should consider the level of this bit FIRST.
© 2002 Consumer Microcircuits Limited
30
D/878/2
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