Motorola MPC8260 - Manual (Page 640)

22-8 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
Table 22-5 describes BSYNC Þelds.
22.8 SCC BISYNC DLE Register (BDLE)
The BDLE register is used to deÞne the BISYNC stripping and insertion of DLE characters.
When an underrun occurs while a message is being sent in transparent mode, the BISYNC
controller inserts DLE-SYNC pairs until the next buffer is available for transmission.
In transparent mode, the receiver discards any DLE character received and excludes it from
the BCS if the valid bit (BDLE[V]) is set. If the second character is SYNC, the controller
discards it and excludes it from the BCS. If it is a DLE, the controller writes it to the buffer
and includes it in the BCS. If it is not a DLE or SYNC, the controller examines the control
character table and acts accordingly. If the character is not in the table, the buffer is closed
with the DLE follow character error bit set. If the valid bit is not set, the receiver treats the
character as a normal character. When using 7-bit characters with parity, the parity bit
should be included in the DLE register value.
Table 22-5. BSYNC 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 BSYNC stripping
0 Normal mode.
1 BSYNC stripping disabled (BISYNC transparent mode only).
2Р7 С All zeroes
8Ð15 SYNC SYNC character
Bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Field V DIS 0 0 0 0 0 0 DLE
Reset UndeÞned
R/W R/W
Address SCC Base + 0x40
Figure 22-4. BISYNC DLE (BDLE)