HD64570 Datasheet, PDF (206/469 Pages) Hitachi Semiconductor – Serial Communications Adaptor

5.3.2Byte Synchronous Mode
In byte synchronous mode, synchronization of characters is accomplished by adding a SYN
character pattern to the beginning of the transmit or receive data.
MSCI byte synchronous mode supports mono-sync, bi-sync, and external synchronous modes. In
mono- or bi-sync mode, a one- or two-byte SYN character pattern is added for synchronization,
respectively. In external synchronous mode, the SYNC line is activated for synchronization. Byte
synchronous mode is specified with the PRTCL2−PRTCL0 bits of mode register 0 (MD0).
The character format for byte synchronous mode is shown in figure 5.23.
Synchronization
pattern
SYN
SYN
Part to be transferred to the receive buffer
Data field
CRC
CRC
8 bits
8 bits
SYNC = low level (receiver)
8 bits x N (N 1)
External synchronous mode
Mono-sync mode
Bi-sync mode
16 bits
Part to be
transmitted
Note: Data field and CRC fields are received from the least significant bit.
Figure 5.23 Character Format for Byte Synchronous Mode
The SYN character pattern lengths for transmission and reception in byte synchronous mode are
listed in table 5.12.
Table 5.12 SYN Character Pattern Length in Byte Synchronous Mode
Synchronous Mode
Mono-sync
Bi-sync
External synchronous
For Transmission
1 byte
2 bytes
1 byte
For Reception
1 byte
2 bytes
SYNC line used for synchronization
Rev. 0, 07/98, page 190 of 453