
R8C/2C Group, R8C/2D Group
15. Serial Interface
Rev.2.00
Dec 05, 2007
REJ09B0339-0200
15.2
Clock Asynchronous Serial I/O (UART) Mode
The UART mode allows data transmission and reception after setting the desired bit rate and transfer data format.
i = 0 to 2
NOTE:
1. If an overrun error occurs, the receive data (b0 to b8) of the UiRB register will be undefined. The IR
bit in the SiRIC register remains unchanged.
Table 15.4
UART Mode Specifications
Item
Specification
Transfer data formats
Character bit (transfer data): Selectable among 7, 8 or 9 bits
Start bit: 1 bit
Parity bit: Selectable among odd, even, or none
Stop bit: Selectable among 1 or 2 bits
Transfer clocks
CKDIR bit in UiMR register is set to 0 (internal clock): fj/(16(n+1))
fj = f1, f8, f32 n = value set in UiBRG register: 00h to FFh
CKDIR bit is set to 1 (external clock): fEXT/(16(n+1))
fEXT: Input from CLKi pin, n = value set in UiBRG register: 00h to FFh
Transmit start conditions
Before transmission starts, the following are required
- TE bit in UiC1 register is set to 1 (transmission enabled)
- TI bit in UiC1 register is set to 0 (data in UiTB register)
Receive start conditions
Before reception starts, the following are required
- RE bit in UiC1 register is set to 1 (reception enabled)
- Start bit detected
Interrupt request
generation timing
When transmitting, one of the following conditions can be selected
- UiIRS bit is set to 0 (transmit buffer empty):
When transferring data from the UiTB register to UARTi transmit register
(when transmission starts).
- UiIRS bit is set to 1 (transfer ends):
When serial interfac.e completes transmitting data from the UARTi
transmit register
When receiving
When transferring data from the UARTi receive register to UiRB register
(when reception ends).
Error detection
This error occurs if the serial interface starts receiving the next data item
before reading the UiRB register and receive the bit preceding the final
stop bit of the next data item.
Framing error
This error occurs when the set number of stop bits is not detected.
Parity error
This error occurs when parity is enabled, and the number of 1’s in parity
and character bits do not match the number of 1’s set.
Error sum flag
This flag is set is set to 1 when an overrun, framing, or parity error is
generated.