V.22 bis Modem with AT Commands
CMX866
CMX866
D1/D6
Signal
Description
AVDD
Power The positive supply rail for the analogue on-chip
blocks. Levels and thresholds within the device
are proportional to this voltage.
18
DCDN
O/P
O/P
O/P
I/P
The inverted DCD signal used for an RS232
interface with a Level Converter.
19
20
21
22
23
24
DSRN
CTSN
DTRN
RTSN
TXD
The inverted DSR signal used for an RS232
interface with a Level Converter.
The inverted CTS signal used for an RS232
interface with a Level Converter.
The inverted DTR signal used for an RS232
interface with a Level Converter.
I/P
The inverted RTS signal used for an RS232
interface with a Level Converter.
I/P
The non-inverted TD signal used for an RS232
interface with a Level Converter. This pin
accepts data from the external host µC for
transmission over the phone line.
RXD
ESC
O/P
I/P
The non-inverted RD signal used for an RS232
interface with a Level Converter. This pin sends
data to the external host µC which was received
over the phone line.
25
26
An auxiliary pin to force the CMX866 into
Command Mode from Data Mode and remain
off-hook. The ATO command will return the
CMX866 to Data Mode. This pin should be
connected to DVSS if not required.
RIN
O/P
27
The inverted RI signal used for an RS232
interface with a Level Converter. This is a 'wire-
ORable' output for connection to an external
host µC Interrupt Request input. This output is
pulled down to DVSS when active and is high
impedance when inactive. An external pullup
resistor is required (eg. R1 in Figure 2a).
DVDD
Power The positive supply rail for the digital on-chip
blocks. Levels and thresholds within the device
are proportional to this voltage.
28
Notes:
I/P
O/P
BI
T/S
NC
=
=
=
=
=
Input
Output
Bidirectional
3-state Output
No Connection
ã 2004 CML Microsystems Plc
5
D/866/4
CMLMICRO [ CML MICROCIRCUITS ]
