XR22804 Datasheet, PDF (20/47 Pages) Exar Corporation – Hi-Speed USB to 10/100 Ethernet Bridge with 4 UARTs

XR22804
UART Registers
UART registers are accessible via the USB interface using the XR_SET_REG and XR_GET_REG USB commands. Note
that all addresses not listed in this table are reserved or undefined. Upper byte (bits 15:8) not shown in table are also
reserved and should remain 0x00. Writing to any register other than those defined in Table 5 may result in undefined behav-
ior of the device. The addresses for each of UARTs in the XR22804 are the same. Because each UART is assigned a
unique USB address during enumeration by the USB host, a GUI connected to a specific COM port will be directed via the
driver to the appropriate UART channel.
UART Register Map
Address
Register Name
0x040
0x045
UART_ENABLE
FORMAT
0x046
FLOW_CONTROL
0x047
0x048
XON_CHAR
XOFF_CHAR
0x049
ERROR_STATUS
0x04A
0x04B
0x04C
0x04D
0x04E
0x04F
0x050
0x051
0x052
0x054
0x055
0x056
TX_BREAK (MSB)
TX_BREAK (LSB)
RS485_DELAY
GPIO_MODE
GPIO_DIRECTION
GPIO_SET
GPIO_CLEAR
GPIO_STATUS
GPIO_INT_MASK
CUSTOMIZED_INT
PIN_PULLUP_EN
PIN_PULLDOWN_EN
LOOPBACK
0x057
0x05F
IR_MODE
REMOTE_WAKEUP
Table 5: XR22804 Register Map
Bit 7
(15)
0
STOP
0
BREAK
_AC-
TIVE
0
0
0
0
0
0
0
0
TX
TX
0
0
0
Bit 6
(14)
0
0
OVER-
RUN
0
0
0
0
0
0
0
0
RX
RX
0
0
0
Bit 5
(13)
0
PARITY
0
Bit 4
(12)
0
Bit 3
(11)
0
0
AUTO_
RS485
CHAR
CHAR
Bit 2
(10)
Bit 1
(9)
0
RX
DATA_BITS
MODE
PARITY FRAME BREAK
0
0
0
0
GPIO5
GPIO5
GPIO5
GPIO5
GPIO5
0
GPIO5
GPIO5
0
0
0
VALUE [MSB]
VALUE [LSB]
0
0
RS485_
POL
GPIO4 GPIO3
GPIO4 GPIO3
GPIO4 GPIO3
GPIO4 GPIO3
GPIO4 GPIO3
0
0
GPIO4 GPIO3
GPIO4 GPIO3
0
0
0
0
0
RX_EN
VALUE
MODE
GPIO2
GPIO2
GPIO2
GPIO2
GPIO2
0
GPIO2
GPIO2
DTR_
DSR
TX_
PULSE
RI_EN
GPIO1
GPIO1
GPIO1
GPIO1
GPIO1
0
GPIO1
GPIO1
RTS_
CTS
RX_
INVER
T
0
Bit 0
(8)
TX
0
GPIO0
GPIO0
GPIO0
GPIO0
GPIO0
EN
GPIO0
GPIO0
TX_RX
EN
0
© 2015 Exar Corporation
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Rev 1B