Zilog Z80230 - Manual (Page 118)

SCC/ESCC
User Manual
UM010903-0515 Data Communication Modes
111
Transmitter/Receiver Synchronization
The SCC contains a transmitter-to-receiver synchronization function that is used to guarantee that
the character boundaries for the received and transmitted data are the same. In this mode, the
receiver is in Hunt and the transmitter is idle, sending either all 1s or all 0s. When the receiver rec-
ognizes a sync character, it leaves Hunt mode; one character time later the transmitter is enabled
Initializing the Receiver in Character-Oriented Mode
Bit Number
Reg D7 D6 D5 D4 D3 D2 D1 D0 Description
WR4 0 0 0 x 0 0 0 0 Select x1 clock, enable sync mode, & no parity x=0
for 8-bit sync, x=1 for 16-bit sync
WR3 r x 0 1 1 0 0 0 rx=# of Rx bits/char, No auto enable, enter Hunt,
Enable Rx CRC, No sync character load inhibit
WR5 d t x 0 0 0 r 1 d=inverse state of DTR pin, tx=# of Tx bits/char,
use CRC-16, r=inverse state of /RTS pin, CRC
enable
WR6 x x x x x x x x sync character, lower byte
WR7 x x x x x x x x sync character, upper byte
WR10 c 0 0 0 i 0 0 s c=CRC preset, NRZ data, i=idle line condition
s=size of sync character
WR3 r x 0 1 1 0 0 1 Enable R eceiver
WR5 d t x 0 1 0 r 1 Enable Transmitter
WR0 1 0 0 0 0 0 0 0 Reset CRC generator