xr21b1411 Exar Corporation, xr21b1411 Datasheet - Page 17

• Manufacturer Part Number: xr21b1411
• Description: Enhanced 1-ch Full-speed Usb Uart
• Manufacturer: Exar Corporation

REV. 1.1.0
XCVR_EN_DELAY[11:4]: Reserved
These bits are reserved and should be ’0’.
GPIO_MODE[2:0]: GPIO Mode Select
There are 4 modes of operation for the GPIOs. The descriptions can be found in
page
GPIO_MODE[3]: Transceiver Enable Polarity
GPIO_MODE[11:4]: Reserved
These register bits are reserved. When writing to these bits, the value should be ’0’. When reading from these
bits, they are undefined and should be ignored.
This register controls the direction of each GPIO unless the pin usage is defined by the GPIO_MODE register.
GPIO_DIRECTION[5:0]: GPIOx Direction
GPIO_DIRECTION[11:6]: Reserved
These register bits are reserved and should be ’0’.
Writing a ’1’ in this register sets the corresponding GPIO output high. Writing a ’0’ in this register sets the
corresponding GPIO output low. For GPIO pins configured as an input via the GPIO_DIRECTION register this
register has no effect. Bits 11-6 are unused and should be ’0’.
Writing a ’1’ in this register clears the corresponding GPIO output low. Writing a ’0’ to a bit has no effect. Bits
11-6 are unused and should be ’0’.
3.1.1.13
3.1.1.14
3.1.1.15
3.1.1.16
BITS
[2:0]
000
001
010
011
100
Logic 0 = GPIO5 Low for TX
Logic 1 = GPIO5 High for TX
Logic 0 = GPIOx is an input.
Logic 1 = GPIOx is an output.
5.
GPIO0
GPIO0
GPIO0
GPIO0
GPIO0
GPIO0
GPIO_MODE Register Description (Read / Write)
GPIO_DIRECTION Register Description (Read / Write)
GPIO_SET Register Description (Read / Write)
GPIO_CLEAR Register Description (Read / Write)
GPIO1
GPIO1
GPIO1
GPIO1
GPIO1
GPIO1
GPIO2
GPIO2
GPIO2
GPIO2
GPIO2
DSR#
GPIO3
GPIO3
GPIO3
GPIO3
GPIO3
DTR#
T
ABLE
GPIO4
GPIO4
GPIO4
GPIO4
GPIO4
CTS#
7: GPIO M
17
GPIO5
GPIO5
GPIO5
Enable
Enable
XCVR
XCVR
RTS#
ODES
ENHANCED 1-CH FULL-SPEED USB UART
GPIO Mode, All GPIO pins available as GPIO
GPIO4 and GPIO5 used for Auto RTS/CTS HW
Flow Control
GPIO2 and GPIO3 used for Auto DTR/DSR HW
Flow Control
GPIO5 used for Auto Transceiver Enable during
Transmit
GPIO5 used for Auto Transceiver Enable after
address match (See FLOW_CONTROL mode 4).
M
ODE
“Section 1.3, UART” on
D
ESCRIPTION
XR21B1411