CMX969D5 MX-COM, Inc., CMX969D5 Datasheet - Page 19

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

MOTIENT
4.6.2
When the modem is in receive mode, the µC should wait until the BFREE bit of the Status Register is '1', then
write the desired task to the Command Register.
Once the byte containing the desired task has been written to the Command Register, the modem will:
In this way, the µC can read data and write a new task to the modem while the received symbols needed for
this new task are being received and stored in the De-interleave Buffer.
Detailed timings for the various tasks are given in Figure 11 and Figure 12.
4.6.2.1
This ‘task’ allows the AFSD or RXEYE bits to be changed without any other effect.
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4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
B2
SM
Receive Mode:
Set the BFREE bit of the Status Register to '0'.
Wait until enough received symbols are in the De-interleave Buffer.
Decode them as needed, and transfer the resulting binary data to the Data Block Buffer
Then the modem will set the BFREE and IRQ bits of the Status Register to '1', (causing the IRQ
output to go low if the
read from the Data Block Buffer and write the next task to the modem. If more than 1 byte is
contained in the buffer, byte number 0 of the data will be read out first.
0
0
0
0
1
1
1
1
/ARDIS
NULL:
RXIN signal
IRQ
IRQ bit of Status Register
Task from µC to Command Register
Data from Block Buffer to µC
BFREE bit of Status Register
B1
output (
0
0
1
1
0
0
1
1
SM
RD-LAP
B0
IRQ
0
1
0
1
0
1
0
1
EN = '1')
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NULL
SFP
RHB
RILB
SFS
R4S
RSID
RESET
TM
MDC4800 Modem
IRQ
EN
Search for Frame Preamble
Read Header Block
Read Intermediate or Last
Block
Search for Frame Sync
Read 4 symbols
Read Station ID
Cancel any current action
Figure 10: Receive Task Overlapping
bit of the Mode Register has been set to '1') to tell the µC that it may
RD-LAP
for task 1
19
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Task 1
NULL
RHB
RILB
SFS
R8B
RESET
-
-
Unused
Read Header Block
Read Intermediate or Last
Block
Search for Frame Sync
Read 8 bits
Unused
Cancel any current action
for task 2
Task 1 data
MDC
CMX969 Advance Information
Task 2
Doc. # 20480211.002