Motorola MPC8260 User Manual
MOTOROLA
Chapter 22. SCC BISYNC Mode
22-9
Part IV. Communications Processor Module
22.9 Sending and Receiving the Synchronization
Sequence
Sequence
The BISYNC channel can be programmed to send and receive a synchronization pattern
deÞned in the DSR. GSMR_H[SYNL] deÞnes pattern length, as shown in Table 22-7. The
receiver synchronizes on this pattern. Unless SYNL is zero (external sync), the transmitter
always sends the entire DSR contents, lsb Þrst, before each frameÑthe chosen 4- or 8-bit
pattern can be repeated in the lower-order bits.
deÞned in the DSR. GSMR_H[SYNL] deÞnes pattern length, as shown in Table 22-7. The
receiver synchronizes on this pattern. Unless SYNL is zero (external sync), the transmitter
always sends the entire DSR contents, lsb Þrst, before each frameÑthe chosen 4- or 8-bit
pattern can be repeated in the lower-order bits.
22.10 Handling Errors in the SCC BISYNC
The controller reports message transmit and receive errors using the channel BDs, error
counters, and the SCCE. Modem lines can be directly monitored via the parallel port pins.
counters, and the SCCE. Modem lines can be directly monitored via the parallel port pins.
Table 22-6. BDLE Field Descriptions
Bits
Name Description
0
V
Valid. If V = 1 and the receiver is not in hunt mode when a SYNC character is received, this
character is discarded.
character is discarded.
1
DIS
Disable DLE stripping
0 Normal mode.
1 DLE stripping disabled. When DIS is enabled in BDLE and on BSYNC the following cases
0 Normal mode.
1 DLE stripping disabled. When DIS is enabled in BDLE and on BSYNC the following cases
occur:
DLE-DLE sequence. Both characters are written to the memory. The BCS is calculated only on
the second DLE.
DLE-SYNC sequence. Both characters are written to the memory, but neither are included in
the BCS calculation.
DLE-ETX, DLE-ITB, DLE-ETB sequence, both characters are written to memory. The BCS is
calculated only on the second character.
DLE-DLE sequence. Both characters are written to the memory. The BCS is calculated only on
the second DLE.
DLE-SYNC sequence. Both characters are written to the memory, but neither are included in
the BCS calculation.
DLE-ETX, DLE-ITB, DLE-ETB sequence, both characters are written to memory. The BCS is
calculated only on the second character.
2Ð7
Ñ
All zeroes
8Ð15
SYNC
SYNC character
Table 22-7. Receiver SYNC Pattern Lengths of the DSR
GSMR_H[SYNL]
Setting
Bit Assignments
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
00
An external SYNC signal is used instead of the SYNC pattern in the DSR.
01
4-Bit
10
8-Bit
11
16-Bit