Control Registers; Figure 15-2: Uartcn Control Register 0 (Ucnctl0) (1/2) - NEC V850E/PH2 User Manual

15.3 Control Registers

(1) UARTCn control register 0 (UCnCTL0)
The UCnCTL0 register is an 8-bit register that controls the UARTCn serial transfer operation.
This register can be read or written in 8-bit or 1-bit units.
Reset input sets this register to 10H.
Caution: Be sure to set the UCnPWR bit = 1 and the UCnRXE bit = 1 while the RXDCn pin is
high level (when UCnRDL bit of UCnOP0 register = 0).
If the UCnPWR bit = 1 and the UCnRXE bit = 1 are set while the RXDCn pin is low
level, reception will inadvertently start.

Figure 15-2: UARTCn Control Register 0 (UCnCTL0) (1/2)

After reset: 10H
7
UCnCTL0 UCnPWR UCnTXE UCnRXE
(n = 0, 1)
UCnPWR
0
1
Operating clock control and UARTCn asynchronous reset are performed with the
UCnPWR bit. The TXDCn pin output is fixed to high level by setting the UCnPWR bit to 0.
UCnTXE
0
1
• The TXDCn pin output is fixed to high level by setting the UCnPWR bit to 0. Since the
UCnTXE bit is initialized by the operating clock, to initialize the transmission unit, set
UCnTXE from 0 to 1, and 2 clocks later, the transmission enabled status is entered.
• When UCnPWR bit = 0, the value written to the UCnTXE bit is ignored.
UCnRXE
0
1
• The receive operation is stopped by setting the UCnRXE bit to 0. Therefore, even if the
prescribed data is transferred, no reception completion interrupt is output and the
UARTCn reception data register (UCnRX) is not updated. Since the UCnRXE bit is
synchronized using the operating clock, to initialize the reception unit, set UCnRXE
from 0 to 1, and 2 clocks later, the reception enabled status is entered.
• When UCnPWR bit = 0, the value written to the UCnRXE bit is ignored.
612
Chapter 15 Asynchronous Serial Interface C (UARTC)
R/W
6 5
Stops clock operation (UARTCn reset asynchronously)
Enables operating clock operation
Stops transmission operation
Enables transmission operation
Stops reception operation
Enables reception operation
User's Manual U16580EE3V1UD00
Address: UC0CTL0 FFFFFA00H,
UC1CTL0 FFFFFA20H
4 3
UCnDIR UCnPS1
UARTCn Operation Control
Transmission Operation Enable
Reception Operation Enable
2 1
UCnPS0 UCnCL UCnSL
0