
R8C/38T-A Group
20. Serial Interface (UART2)
Under development Preliminary document
Specifications in this document are tentative and subject to change.
R01UH0241EJ0010 Rev.0.10
Page 428 of 730
Aug 05, 2011
20.3.2.5
TXD and RXD I/O Polarity Inverse Function
This function inverts the polarities of the TXD2 pin output and RXD2 pin input. The logic levels of all I/O data
Figure 20.12
TXD and RXD I/O Polarity Inversion
20.3.2.6
CTS/RTS Function
The CTS function is used to start transmit and receive operations when a low level is applied to the CTS2 pin.
Transmit and receive operations start when the CTS2 pin is held low. If the input level is switched to high
during a transmit or receive operation, the operation stops before the next data.
For the RTS function, the RTS2 pin outputs a low level when the MCU is ready for a receive operation. The
output level goes high at the first falling edge of the RXD2 pin.
CRD bit in the U2C0 register = 1 (CTS/RTS function disabled):
CTS2 pin input is unused, and RTS2 pin output is high
CRD bit = 0 and CRS bit = 0 (CTS function selected):
CTS2 pin input is active, and RTS2 pin output is high
CRD bit = 0 and CRS bit = 1 (RTS function selected):
CTS2 pin input is unused, and RTS2 pin output is active
ST: Start bit
P: Parity bit
SP: Stop bit
D0
D1
D2
D3
D4
D5
D6
D7
P
SP
ST
SP
ST
D3
D4
D5
D6
D7
P
D0
D1
D2
Transfer clock
TXD2
(not inverted)
TXD2
(inverted)
(1) IOPOL Bit in U2MR Register = 0 (not inverted)
The above applies under the following conditions:
UFORM bit in U2C0 register = 0 (LSB first)
STPS bit in U2MR register = 0 (one stop bit)
PRYE bit in U2MR register = 1 (parity enabled)
Transfer clock
(2) IOPOL Bit in U2MR Register = 1 (inverted)
D0
D1
D2
D3
D4
D5
D6
D7
P
SP
ST
RXD2
(not inverted)
SP
ST
D3
D4
D5
D6
D7
P
D0
D1
D2
RXD2
(inverted)