HD64570 HITACHI [Hitachi Semiconductor], HD64570 Datasheet - Page 32

• Manufacturer Part Number: HD64570
• Description: Serial Communications Adaptor
• Manufacturer: HITACHI [Hitachi Semiconductor]

1.7
1.7.1
The normal SCA operating mode is full duplex (figure 1.6). The SCA can transmit and receive
simultaneously, using two separate lines.
In auto echo mode (figure 1.6), the SCA automatically retransmits all received data. Data received
on the RXD line are retransmitted on the TXD line, and received data are simultaneously input to
the receiver in the SCA.
In local loop back mode (figure 1.6), transmit data supplied to the SCA are automatically
transferred to the receive data buffer in the SCA. Data received on the RXD line are retransmitted
on the TXD line.
1.7.2
The SCA supports asynchronous, byte-synchronous (bisync, X.21, DDCMP, etc.) and bit-
synchronous (frame relay, HDLC, SDLC, X.25 link level/LAPB, LAPD, etc.) protocols. Each
communication mode has its own format for transmitting data (figure 1.7).
Rev. 0, 07/98, page 16 of 453
General Description of Functions
Operating Modes of Serial Section
Transmission Formats
SCA
SCA
A
(simultaneous transmit and receive)
Figure 1.6 Operating Modes
Local loop back mode
Auto echo mode
Full duplex
TxD
RxD
TxD
RxD
B