HD64570 Datasheet, PDF (224/469 Pages) Hitachi Semiconductor – Serial Communications Adaptor

5.4.2 Transmit Clock Sources
The transmit clock sources are shown in figure 5.30. When the transmit baud rate generator
output serves as the transmit clock, the TXC line functions as the transmit clock output line.
The receive clock is used as the transmit clock when the clock is extracted by the ADPLL or is in
bit synchronous loop mode.
In asynchronous mode, the actual bit rate is determined by the clock mode (1/1, 1/16, 1/32, or
1/64). In byte or bit synchronous mode, 1/1 clock mode is automatically selected. For details, see
section 5.2.2, MSCI Mode Register 1 (MD1).
Transmit
CLK
baud rate
generator
TXC line input
Receive clock
f _{BRG =}
f_CLK
TMC
÷ 2^TXBR
(TMC: 1 to 256, TXBR: 0 to 9)
f _BR
Transmit clock
(1/1, 1/16, 1/32 or
1/64 clock mode)
f_CLK : System clock (CLK) frequency
Figure 5.30 Transmit Clock Sources
Rev. 0, 07/98, page 208 of 453