
16.2.2.2 LSB First or MSB First
As shown in
Figure 16.45, the UFORM bit in the UiC0 register (i = 5, 6) determines a bit order. This function is
enabled when transfer data length is 8 bits long.
Figure 16.45
Bit Order
16.2.2.3 CTS/RTS Function
When the CTS function is used, the transmit/receive operation starts when a low-level (“L”) signal is applied to
the CTSi pin (i = 5 and 6). When a high-level (“H”) signal is applied to the CTSi pin during transmitting/
receiving, the transmit/receive operation stops after the ongoing transmit/receive operation is completed. To use
the CTS function, select the I/O port with the function select register, set the CRD bit in the UiC0 register to 0
(CTS function enabled), and set the CRS bit in the UiC0 register to 0 (CTS function selected).
When the RTS function is used, the RTSi pin outputs an “H” at the first falling edge of the clock input to the
CLKi pin, and outputs an “L” under the following conditions.
The RI bit in the UiC1 register is 0 (no data in the UiRB register).
The TE bit in the UiC1 register is set to 1 (transmit operation enabled).
The RE bit in the UiC1 register is set to 1 (receive operation enabled).
The TI bit in the UiC1 register is 0 (data in the UiTB register).
To use the RTS function, select the RTSi pin with the function select register.
(1) When the UFORM bit in the UiC0 register (i = 5, 6) is set to 0 (LSB first)
ST
D0
D2
D3
D4
D5
SP
D1
(2) When the UFORM bit is set to 1 (MSB first)
TXDi
RXDi
NOTE:
1. The above applies when the CKPOL bit in the UiC0 register is set to 0 (transmit data output at the falling edge and
receive data input at the rising edge of the serial clock).
ST: Start bit
P: Parity bit
SP: Stop bit
D6
D7
P
ST
D0
D2
D3
D4
D5
SP
D1
D6
D7
P
ST
D7
D5
D4
D3
D2
SP
D6
TXDi
RXDi
D1
D0
P
ST
SP
P
D7
D5
D4
D3
D2
D6
D1
D0
"H"
"L"
"H"
"L"
"H"
"L"
"H"
"L"