RDC
®
RISC DSP Controller
R8810LV
RDC Semiconductor Co.
Rev:1.2
Subject to change without notice
63
Asynchronous Serial Port
R8810 asynchronous serial port provides the TXD, RXD pins for the full duplex bi-directional data transfer and without
handshaking signals. The UART port supports : 8-bit or 7-bit data transfer; odd parity, even parity, or no parity; 1 or 2 stop bits.
DMA transfers through the serial port are not supported
The receive/transmit clock is based on the microprocessor clock. The serial port can be used in power-saved mode, but the
transfer rate must be adjusted to correctly reflect the new internal operating frequency. Software is programmed through the
80h, 82h, 84h, 86h, 88h registers to configure the asynchronous serial port.
Bit 15-12: Reserved
Bit 11: TXIE
, Transmit Holding Register Empty Interrupt Enable.
This bit is set 1 to enable serial port to generates an interrupt request when the transmit holding register is empty.
Bit 9: LOOP,
Loopback.
Set 1: The serial port in the loopback mode. In this mode, the transmit shift register is connect to the transmit shift
register internal and the TXD pin output high. It provides the serial port testing in this mode.
Bit 8: BRK
, Send Break.
Offset : 80h
0
Reset Value : 0000h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Reserved
Serial Port Control Register
PMODE
WLGN
STP
TMOD RSIE
RMODE
BRKVAL
BRK
LOOP
RXIE
TXIE
Transmit
Data Register(84h)
Transmit
Hold Register
Transmit
Shift Regoster
Receive
Data Register(86h)
Receive
Buffer
Receive Shift
Register
TXD
Control
Logic
Control Register(80h)
Status Register(82h)
Baud Rate
Divisor Register(88h)
Interrupt Request
RXD
Internal Address/Data Bus
Serial Port Block Diagram
16 bit
8 bit
8 bit
16 bit
16 bit
8 bit
8 bit