Interfacing
Communication with, and control of, the
CMX869A
by
the host µC is via the CML C-BUS serial data interface;
a hardware/software interface compatible with most
processor interfaces.
C-BUS is operational in both ‘normal’ and ‘powersave’
modes of this product.
To increase data transfer rates and minimise µC overheads,
the CMX869A C-BUS can be set to operate in either 1 or
2 character mode.
On-chip programmable
Tx and Rx USARTs
are available for
use with asynchronous data and to allow the transmission
and reception of unformatted synchronous 8/16-bit words.
An HDLC receive-only function is included on-chip and
incorporates 16-bit CRC checks and flag-stripping.
. . . from Relay Drive Output
Tx Output
Buffer
Tx Output
Hook-Switch
Relay Drive
Output
Interrupt
Serial
Clock
Command
Data
Chip Select
Reply
Data
C-BUS Serial Interface
C-BUS
Serial
Interface
+
Tx / Rx
Data
Registers
+
USART
Tx Level
Control
Host
µC
Local
Analogue
Loopback
Rx Gain
Control
2 or 4 Wire
Line
Interface
(DAA)
Rx Input
+
-
The
CMX869A
is compatible with either a 2-wire or
4-wire telephone installation providing additionally,
a ringing signal detector input and a relay drive
output.
The Ring Detector circuitry is operational in both
‘normal’ and ‘powersave’ modes.
Tx output levels and the Rx input gain can be adjusted
on chip with an additional Rx input gain setting for
Type 1 Caller Line ID.
The Relay Drive output is available to provide a
software-controlled ‘hook switch’ function.
Ring Detect
Input
Ring
Detector
Rx Input
Amplifier
Digital Interface
. . . to Ring Detect Input
Analogue Interface
Rx and Tx USART
Can be programmed for all modem modes
Synchronous data
Start - Stop characters
HDLC (receive-only) mode
Local Analogue Loopback
An overall on-chip test mode from Tx Data Out to Rx Signal In
Enables the software developer to test and debug prototype programmes
- Telephone Telemetry - Remote Utility Meter Reading - Alarm and Security - Industrial Control - EPOS and ATM - Feature and Pay Phones - Internet Appliances - Set-Top Boxes -
Data Operations
V.32bis, V.32, V.22bis and V.22 Auto-modem Operation
Automatic response to ‘Retrain’ and ‘Rate Re-negotiation’ requests from distant modems
‘Start Automodem’ commands available for calling and answer modes
‘Initiate Retrain’ and ‘Initiate Rate Re-negotiation’ commands available
A separate Status Register reports progress
V.22bis, V.22, V.23, V.21, Bell 202 and Bell 103 Manual Modem Operation
Pattern detection
Equalisation
Data scrambling and de-scrambling
Energy detection
3
CMLMICRO [ CML MICROCIRCUITS ]
