MX919B View Datasheet(PDF) - MX-COM Inc
Part Name
Description
MFG CO.
'MX919B' PDF : 48 Pages View PDF
4-Level FSK Modem Data Pump
Page 20 of 47
MX919B PRELIMINARY INFORMATION
4.5.2.15 TIB: Transmit Intermediate Block
This task takes 12 bytes of data from the Data Block Buffer, updates the 4-byte CRC2 checksum for inclusion
in the 'Last' block, translates the 12 data bytes to 4-level symbols (with FEC), interleaves the symbols, and
transmits the result as a formatted 'Intermediate' 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'.
4.5.2.16 TLB: Transmit Last Block
This task takes 8 bytes of data from the Data Block Buffer, updates and appends the 4-byte CRC2 checksum,
translates the resulting 12 bytes to 4-level symbols (with FEC), interleaves the symbols, and transmits the
result as a formatted 'Last' 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'.
4.5.2.17 T4S: Transmit 4 Symbols
This command is similar to T24S but takes only one byte from the Data Block Buffer, transmitting it as four 4-
level symbols.
4.5.2.18 RESET: Stop any current action
This 'task' takes effect immediately, and terminates any current action (task, AQSC or AQLEV) the modem
may be performing and sets the BFREE bit of the Status Register to '1', without setting the IRQ bit. It should
be used when VDD is applied, to set the modem into a known state.
Note: Due to delays in the transmit filter, it will take several symbol times for any change to appear at the
TXOUT pin.
4.5.2.19 Task Timing
The following table and figures describe the duration of tasks and timing sequences for Tx and Rx operation.
Task
Time
(symbol times)
t1
Modem Idle state. Time from writing first task to application of first
transmit bit to Tx RRC filter.
Any
1 to 2
t2
Time from application of first symbol of the task to the Tx RRC filter
until BFREE goes to a logic ‘1’.
T24S
5
THB/TIB/TLB 16
T4S
0
t3 Time to transmit all symbols of the task.
T24S
24
THB/TIB/TLB 66
T4S
4
t4
Max time allowed from BFREE going to a logic ‘1’ (high) for next task
(and data) to be written to modem.
T24S
18
THB/TIB/TLB 49
T4S
3
t5 Time to receive all symbols of task.
SFS
SFSH
RHB/RILB
R4S
24 (minimum)
90 (minimum)
66
4
SFS
21
t6
Maximum time between first symbol of task entering the de-interleave
circuit and the task being written to modem.
SFSH
RHB/RILB
21
49
R4S
3
t7
Maximum time from the last bit of the task entering the de-interleave
circuit to BFREE going to a logic ‘1’ (high).
Any
1
©2001 MX•COM, INC.
www.mxcom.com Tele: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480170.003
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.
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