HD64570 Datasheet, PDF (36/469 Pages) Hitachi Semiconductor – Serial Communications Adaptor

1.7.5 Transmit/Receive Clock Selection
MSCI channels 0 and 1 in the SCA are full-duplex transceivers that support asynchronous, byte-
synchronous, and bit-synchronous transmission formats. The transmit clock (figure 1.9) can be
selected independently on each channel. The selectable clock sources include the built-in baud rate
generator, external clock input, and the receive clock (figure 1.10).
φ
TXC
line input
Receive
clock
Baud rate
generator
f _BRG
=
fφ
TMC
TXBR
÷2
Transmit
clock
(TMC: 1 to 256, TXBR: 0 to 9) ^selector
(for
100
transmitting)
000
110
Transmit clock
(1/1, 1/16*, 1/32*, or
1/64* clock mode)
* Asynchronous mode
TXCS 2 to 0
(TXS bits 6 to 4)
TXS: MSCI TX clock source register
Figure 1.9 Transmit Clock Source
Rev. 0, 07/98, page 20 of 453