MSK Modem
16
MX809
6.5 RX Timing
A – Address bytes
C – Checksum bytes
D – Data bytes
H – Hang bit
P – Preamble bytes
- Don’t care state
TX only – In TX, Preamble, and SYNC are
loaded as data from the microcontroller.
6.5.1 RX SYNC / SYNC Required Before Every Message, Rx Checksum Not Enabled
RX/TX
P1 P2
NOTE 1
P
SYNC
A1 A2 A3
NOTE 2
A
SYNC
NOTE 3
A1 A2 A3
RX INPUT
IRQ
READ STATUS REGISTER
SYNC DETECT
(OR SYNC DETECT)
RX DATA READY
READ RX DATA BUFFER
A1 A2 A3
A
SYNC/SYNC PRIME
CHECKSUM ON/OFF
Figure 9: RX SYNC / SYNC Required Before Every Message, RX Checksum not Enabled
Notes:
1. Any number of preamble bits can occur here.
2. Any number of address/data bytes can occur here.
3. Any number of bits can occur here
4. RX Freeformat set high.
6.5.2 RX Additional Data Follows Initial Address (6 Data & 2 Checksum Bytes) Data, RX checksum
Enabled
RX/TX
SYNC
A1 A2 A3 A4 A5 A6 C1 C2 D1 D2 D3 D4 D5 D6 C1 C2 D1
RX INPUT
P1 P2
P
NOTE 1
IRQ
READ STATUS
REGISTER
SYNC DETECT
(OR SYNC
DETECT)
RX DATA READY
READ RX
DATA BUFFER
RX CHECKSUM
TRUE
SYNC/SYNC
PRIME
CHECKSUM
ON/OFF
Figure 10: RX Additional Data Follows Initial Address (6 Data & 2 Checksum Bytes) Data , RX
Checksum Enabled
Notes:
1. Any number of preamble bits can occur here.
2. RX Freeformat set high.
ꢀ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
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CMLMICRO [ CML MICROCIRCUITS ]
