W90N745CD/W90N745CDG
6.10.6 High speed UART Controller
The High Speed Universal Asynchronous Receiver/Transmitter (HS_UART) performs a serial-to-
parallel conversion on data characters received from the peripheral, and a parallel-to-serial conversion
on data characters received from the CPU. There are five types of interrupts, they are, transmitter
FIFO empty interrupt, receiver threshold level reaching interrupt, line status interrupt (overrun error or
parity error or framing error or break interrupt) ,time out interrupt, and Modem status interrupt . One
64-byte transmitter FIFO (TX_FIFO) and one 64-byte (plus 3-bit of error data per byte) receiver FIFO
(RX_FIFO) has been built in to reduce the number of interrupts presented to the CPU. The CPU can
completely read the status of the UART at any time during the operation. The reported status
information includes the type and condition of the transfer operations being performed by the UART,
as well as any error conditions (parity, overrun, framing, or break interrupt) found. The UART includes
a programmable baud rate generator that is capable of dividing crystal clock input by divisors to
produce the clock that transmitter and receiver needed. The equation is
Baud Out = crystal clock / 16 * [Divisor + 2].
The UART includes the following features:
y
Transmitter and receiver are buffered with a 64-byte FIFO each to reduce the number of
interrupts presented to the CPU.
y
y
Subset of MODEM control function(selected by IP)
Fully programmable serial-interface characteristics:
¾
¾
¾
¾
5-, 6-, 7-, or 8-bit character
Even, odd, or no-parity bit generation and detection
1-, 1&1/2, or 2-stop bit generation
Baud rate generation
y
y
y
False start bit detection
Full-prioritized interrupt system controls
Not support Loop back mode
6.10.6.1.
High Speed UART Control Registers Map
R: read only, W: write only, R/W: both read and write, C: Only value 0 can be written
REGISTER
OFFSET R/W
DESCRIPTION
RESET VALUE
HSUART_RBR
0x00
0x00
0x04
0x00
0x04
R
Receive Buffer Register (DLAB = 0)
Undefined
HSUART_THR
HSUART_IER
HSUART_DLL
HSUART_DLM
W
Transmit Holding Register (DLAB = 0)
Undefined
R/W Interrupt Enable Register (DLAB = 0)
R/W Divisor Latch Register (LS)(DLAB = 1)
R/W Divisor Latch Register (MS)(DLAB = 1)
0x0000_0000
0x0000_0000
0x0000_0000
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