Z16C30_08 Datasheet, PDF (46/102 Pages) Zilog, Inc. – CMOS USC Universal Serial Controller

Z16C30
Product Specification
42
grammed to automatically send CRC on either an underrun or at the end of a programmed
message length.
Bisync Mode—This mode is identical to monosync mode except that character synchroni-
zation requires two successive characters for synchronization. The two characters need not
be identical.
HDLC Mode—In this mode, the receiver recognizes flags, performs optional address
matching, accommodates extended address fields, 8- or 16-bit control fields and logical
control fields, performs zero deletion and CRC checking. The receiver is capable of
receiving shared-zero flags, recognizes the abort sequence and can receive arbitrary length
messages. The transmitter automatically sends opening and closing flags, performs zero
insertion and can be programmed to send an abort, an extended abort, a flag or CRC, and a
flag on transmit underrun. The transmitter can also automatically send the closing flag
with optional CRC at the end of a programmed message length. Shared-zero flags are
selected in the transmitter and a separate character length may be programmed for the last
character in the frame.
Bisync Transparent Mode—In this mode, the synchronization pattern is DLE–SYN, pro-
grammable selected from either ASCII or EBCDIC encoding. The receiver recognizes
control character sequences and automatically handles CRC calculation without CPU
intervention. The transmitter can be programmed to send either SYN, DLE–SYN, CRC–
SYN, or CRC–DLE–SYN upon underrun and can automatically send the closing DLE–
SYN with optional CRC at the end of a programmed message length.
NBIP Mode—This mode is identical to async except that the receiver checks for the status
of an additional address/data bit between the parity bit and the stop bit. The value of this
bit is FIFO’ed along with the data. This bit is automatically inserted in the transmitter with
the value that is FIFO’ed with the transmit data.
802.3 Mode—This mode implements the data format of IEEE 802.3 with 16-bit address
compare. In this mode, DCD and CTS are used to implement the carrier sense and colli-
sion detect interactions with the receiver and transmitter.
Slaved Monosync Mode—This mode is available only in the transmitter and allows the
transmitter (operating as though it were in monosync mode) to send data that is byte-syn-
chronous to the data being received by the receiver.
HDLC Loop Mode—This mode is also available only in the transmitter and allows the
USC to be used in an HDLC loop configuration. In this mode, the receiver is programmed
to operate in HDLC mode so that the transmitter echoes received messages. Upon receipt
of a particular bit pattern (actually a sequence of seven consecutive ones) the transmitter
breaks the loop and inserts its own frame(s).
Data Encoding
The USC may be programmed to encode and decode the serial data in any of eight differ-
ent ways as displayed in Figure 28 on page 44. The transmitter encoding method is
selected independently of the receiver decoding method.
DS007902-0708
PRELIMINARY
Functional Description