SCC BISYNC Mode
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 23-9
23.9 Sending and Receiving the Synchronization Sequence
The BISYNC channel can be programmed to send and receive a synchronization pattern defined in the
DSR. GSMR_H[SYNL] defines pattern length, as shown in Table 23-7. The receiver synchronizes on this
pattern. Unless SYNL is zero (external sync), the transmitter always sends the entire DSR contents, lsb
first, before each frame—the chosen 4- or 8-bit pattern can be repeated in the lower-order bits.
23.10 Handling Errors in the SCC BISYNC
The controller reports message transmit and receive errors using the channel BDs, error counters, a nd the
SCCE. Modem lines can be directly monitored via the parallel port pins. Table 23-8 describes transmit
errors.
Table23-6. BD LE 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.
1 DIS Disable DLE stripp ing
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.
2–7 All zeros
8–15 DLE DLE character
Table23-7. 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