Renesas M16C Series User Manual page 197

M30240 Group
(g) Function for choosing a transmission interrupt factor.
The timing to generate a transmission interrupt can be selected from the following: the instant the
transmission buffer is emptied or the instant the transmission register is emptied. When transmission
buffer empty timing is selected, an interrupt occurs when the transmitted data is moved from the trans-
mission buffer to the transmission register. Therefore, data can be transmitted in succession. When
transmission register empty timing is selected, an interrupt occurs when the data transmission is com-
plete.
(h) TxD, RxD I/O polarity reverse function
This function is to reverse the polarity of the TxD port output level and the polarity of the RxD port input
level.
The following are some examples in which various functions (a) through (g) are selected:
• Transmission Operation WITH: CTS function, trans-
mission at falling edge of transfer clock, LSB First,
interrupt at instant transmission buffer is emptied;
WITHOUT transfer clock output to multiple pins
function
• Transmission Operation WITH: CTS/RTS function
disabled, transmission at falling edge of transfer
clock, LSB First, interrupt at instant transmission is
completed; WITH transfer clock output to multiple
pins function (UART0 selection available)
• Reception WITH: RTS function, reception at falling
edge of transfer clock, LSB First, successive recep-
tion mode disabled; WITHOUT transfer clock output
to multiple pins function
2.4.1.6 Input to the serial I/O and the direction register
To input an external signal to the serial I/O, set the direction register of the relevant port to input.
2.4.1.7 Pins related to the serial I/O
• CTS0, CTS1, CTS2 pins
• RTS0, RTS1, RTS2 pins
• CLK0, CLK1, CLK2 pins
• RxD0, RxD1, RxD2 pins
• TxD0, TxD1, TxD2 pins
• CLKS1 pin
Rev.1.00 Sep 24, 2003 Page 179 of 360
Clock-Synchronous Serial I/O
See section 2.4.2.1
See section 2.4.2.2
See section 2.4.2.3
Input pins for the CTS function
Output pins for the RTS function
Input/output pins for the transfer clock
Input pins for data
Output pins for data (Because TxD2
pin is N-channel open drain, this pin
needs pull-up resistor).
Output pin for transfer clock. Can be
used as transfer clock output pin in the
transfer clock output to multiple pins
function.