DATA BULLETIN
MX809
Features
Half-Duplex 1200bps MSK Modem
operating under C-BUS control
Software Selectable Checksum
Generation and Error Checking in
accordance with MPT1327
RECOVERED
CLOCK
1200bps MSK Modem
PRELIMINARY INFORMATION
Low Power Operation
Member of DBS800 Family (C-BUS
Compatible)
CHECKSUM
GEN/CHECK
V
DD
BYTE COUNTER
TX OUT
RX IN
MSK
RECEIVER
RECOVERED
CLOCK
DATA REGISTER 1
DATA REGISTER 2
ä
MSK
TRANSMITTER
XTAL/
CLOCK
XTAL
CLOCK
GENERATOR
ä
RX SYNC
DETECT
SYNC/SYNC
DETECT
ä
ä
V
BIAS
RX SYNC
DETECT
AMP IN
TX DATA BUFFER
_
ä
RX FREEFORMAT
RX DATA BUFFER
CS
REPLY
DATA
SERIAL
CLOCK
COMMAND
DATA
WAKE
INTERRUPT
ENABLE
RX DATA
READY
TX DATA
READY
TX IDLE
+
UNCOMMITTED
AMPLIFIER
AMP OUT
C-BUS
INTERFACE
AND
CONTROL
LOGIC
SYNC PROGRAM
LOW - HIGH
V
BIAS
ä
ä
8-BIT PARALLEL BUS
ä
V
SS
ADDRESS
DECODER
ADDRESS
SELECT
The MX809 is an intelligent, half-duplex 1200-baud MSK Modem, which operates under C-BUS control. This
modem provides software selectable checksum generation and error checking in accordance with MPT1327.
In TX Mode the MX809 will:
1.
a) Accept from the host and transmit 8-bit bytes of data as instructed (preamble, sync, address, and data), or
b) Internally calculate and inset a 2 byte checksum based on the preceding 6 bytes f data, or
c) Disable the internal checksum generator and continuously transmit the data supplied.
2.
Transmit 1 hang-bit and go to TX idle when all loaded data bytes have been transmitted.
ä
RX SYNC
DETECT
RX SYNC
DETECT
ä
CONTROL
REGISTER
ä
STATUS
REGISTER
INTERRUPT
GENERATOR
IRQ
In RX Mode the MX809 will:
1.
2.
Detect and carry out bit synchronization within 16 bits.
a) Search and detect the user-programmed Sync (or its opposite logic sense) Word and carry out frame
synchronization. Data will then be output in 8-bit bytes via the RX Data Buffer.
b) Use the received checksum to calculate the presence of any errors, setting the Status Register accordingly.
3.
Make the incoming data directly available via the RX Data Buffer (RX Freeformat), overriding the synchronization
requirements.
RX input timing is achieved by recovering an RX clock from the incoming data stream. Output tones are
timed to the internally generated TX clock. Filter, register clocks, and transmit MSK tone frequencies are
derived internally from the external Xtal or clock pulse input.
A 4.032MHz Xtal or clock input is required for compliance with the MPT1327 Signaling Specification. Note:
All information contained in this data bulletin is specified using a 4.032MHz Xtal, 1200bps baud rate, with
Mark and Space frequencies of 1200Hz and 1800Hz. The MX809 has a non-committed amplifier on-chip for
general applications in the DBS 800 series.
The MX809 may be used with a 5.0V power supply and is available in the following packages:
24-pin PLCC (MX809LH), and 24-pin CERDIP (MX809J).
1998
MX-COM, Inc.
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480036.004
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
CMLMICRO [ CML MICROCIRCUITS ]
