
Clock-Synchronous Serial I/O
Mitsubishi microcomputers
M30201 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
262
In receiving data in clock-synchronous serial I/O mode, choose functions from those listed in Table 2.5.3.
Operations of the circled items are described below. Figure 2.5.11 shows the operation timing, and Fig-
ures 2.5.12 and 2.5.13 show the set-up procedures.
2.5.4 Operation of Serial I/O (reception in clock-synchronous serial I/O mode)
Table 2.5.3. Choosed functions
Note: This can be selected only when UART0 is used in combination with the internal clock.
Operation (1) Writing dummy data to the UART0 transmit buffer register, setting the receive enable bit to
“1”, and the transmit enable bit to “1”, makes the data receivable status ready.
(2) In synchronization with the first rising edge of the transfer clock, the input signal to the RxD0
pin is stored in the highest bit of the UART0 receive register. Then, data is taken in by shifting
right the content of the UART0 reception data in synchronization with the rising edges of the
transfer clock.
(3) When 1-byte data lines up in the UART0 receive register, the content of the UART0 receive
register is transmitted to the UART0 receive buffer register. The transfer clock stops at “H”
level. At this time, the receive complete flag and the UART0 receive interrupt request bit goes
to “1”.
(4) The receive complete flag goes to “0” when the lower-order byte of the UART0 buffer register
is read.
Item
Set-up
Transfer clock
source
Internal clock (f1 / f8 / f32 / fc)
External clock (CLK0 pin)
CLK polarity
Output transmission data at the falling edge of the transfer clock
Output transmission data at the rising edge of the transfer clock
O
Continuous receive
mode
Disabled
Enabled
Output transfer clock
to multiple pins
(Note)
Not selected
Selected
O
Transfer clock
LSB first
MSB first
O