Preliminary
S3C2451 RISC MICROPROCESSOR
UART
15-7
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
Loopback Mode
The S3C2451X UART provides a test mode referred to as the Loopback mode, to aid in isolating faults in the
communication link. This mode structurally enables the connection of RXD and TXD in the UART. In this mode,
therefore, transmitted data is received to the receiver, via RXD. This feature allows the processor to verify the
internal transmit and to receive the data path of each SIO channel. This mode can be selected by setting the
loopback bit in the UART control register (UCONn).
Infrared (IR) Mode
The S3C2451X UART block supports infrared (IR) transmission and reception, which can be selected by setting
the Infrared-mode bit in the UART line control register (ULCONn). Figure 15-4 illustrates how to implement the IR
mode.
In IR transmit mode, the transmit pulse comes out at a rate of 3/16, the normal serial transmit rate (when the
transmit data bit is zero); In IR receive mode, the receiver must detect the 3/16 pulsed period to recognize a zero
value (see the frame timing diagrams shown in Figure 15-6 and 15-7).
IrDA Tx
Encoder
0
1
0
1
IrDA Rx
Decoder
TxD
RxD
TxD
IRS
RxD
RE
UART
Block
Figure 15-4. IrDA Function Block Diagram