Zilog Z80230 - Manual (Page 111)

SCC/ESCC
User Manual
UM010903-0515 Data Communication Modes
104
Once the sync character-oriented mode has been selected, any of the four sync character lengths
may be selected: 6 bits, 8 bits, 12 bits, or 16 bits.
Table lists the write register bit setting for selecting sync character length.
The arrangement of the sync character in WR6 and WR7 is displayed in Figure on page 105.
For those applications requiring any other sync character length, the SCC makes provision for an
external circuit to provide a character synchronization signal on the /SYNC pin. This mode is
selected by setting bits D5 and D4 of WR4 to 1. In this mode, the Sync/Hunt bit in RR0 reports the
state of the /SYNC pin, but the receiver is still placed in Hunt mode when the external logic is
searching for a sync character match. Two receive clock cycles after the last bit of the sync charac-
ter is received, the receiver is in Hunt mode and the /SYNC pin is driven Low, then character
Sync Character Length Selection
Sync Length WR4,D5 WR4,D4 WR10,D0
6 bits 0 0 1
8 bits 0 0 0
12 bits 0 1 1
16 bits 0 1 0