CMX969D5 MX-COM, Inc., CMX969D5 Datasheet - Page 17

• Manufacturer Part Number: CMX969D5
• Description: MOTIENT/ARDIS RD-LAP MDC4800 Modem
• Manufacturer: MX-COM, Inc.

MOTIENT
4.6.1.1
This task, which is intended to facilitate the transmission of Symbol and Frame Sync patterns as well as
special test sequences, takes 6 bytes of data from the Data Block Buffer and transmits them as 24 4-level
symbols without any CRC, FEC, interleaving or adding any 'S' symbols.
Byte 0 of the Data Block Buffer is sent first, byte 5 last.
Once the modem has read the data bytes from the Data Block Buffer, the BFREE and IRQ bits of the Status
Register will be set to '1', indicating to the µC that it may write the data and command byte for the next task to
the modem.
The following tables show what data has to be written to the Data Block Buffer to transmit the CMX969
Symbol and Frame Sync sequences:
4.6.1.2
This ‘task’ has no effect in transmit mode.
4.6.1.3
This task is similar to the RD-LAP mode T24S task, but transmits 40 bits taken from the first 5 bytes in the
Data Block Buffer. Data block buffer byte 0 is transmitted first, byte 4 last, within each byte the MSB is
transmitted first, LSB last. (See Section 4.6.5.8)
4.6.1.4
In RD-LAP mode this task takes 10 bytes of data from the Data Block Buffer, calculates and appends the 2-
byte CRC1 checksum, translates the result to 4-level symbols (with FEC), interleaves the symbols and
transmits the result as a formatted 'Header' Block, inserting 'S' symbols at 22-symbol intervals.
In MDC mode this task takes 4 bytes of data from the Data Block Buffer, calculates and appends the 2-byte
checksum, adds FEC bits, interleaves the result, inserts channel status bits and transmits the result as a
formatted 'Header' Block.
Once the modem has read the data bytes from the Data Block Buffer, the BFREE and IRQ bits of the Status
Register will be set to '1'.
¤ ¤ ¤ ¤ 2001 MX-COM, Inc.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
SM
/ARDIS
T24S: Transmit 24 Symbols (RD-LAP only)
NULL:
T40B: Transmit 40 Bits (MDC only)
THB: Transmit Header Block (RD-LAP and MDC)
+3
+3
+3
+3
+3
+3
-3
-1
-1
-3
-3
-1
SM
RD-LAP
'Symbol Sync'
'Frame Sync'
+3
+3
+3
+3
+3
+1
+3
+3
Symbols
Symbols
-3
-1
-3
-3
www.mxcom.com Tel: [phone] 744 5050 Fax: [phone]
TM
MDC4800 Modem
+3
+1
+1
+1
-3
-3
-3
-3
-3
-1
-3
-1
+3
+1
+3
+1
+3
+3
-3
-3
-3
-3
-3
-3
Byte 5 :
Byte 0:
Byte 1:
Byte 2:
Byte 3:
Byte 4:
Byte 5:
Byte 0:
Byte 1:
Byte 2:
Byte 3:
Byte 4:
Values written to Data Block Buffer
Values written to Data Block Buffer
17
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00100010
00110111
01001001
11110010
01011011
00011011
11110101
11110101
11110101
11110101
11110101
01011111
Binary
Binary
CMX969 Advance Information
Hex
Hex
F2
5B
1B
22
37
49
F5
F5
F5
F5
F5
5F
Doc. # 20480211.002