XR21V1412
5
REV. 1.3.0
2-CH FULL-SPEED USB UART
GPIOB1/CDB#
21
I/O
UART Channel B general purpose I/O or UART Carrier-Detect input (active low).
This pin has an internal pull-up resistor which is disabled during suspend mode. If
using this GPIO as an input, an external pull-up resistor is required to minimize the
power consumption in the suspend mode.
GPIOB2/DSRB#
20
I/O
UART Channel B general purpose I/O or UART Data-Set-Ready input (active low).
See ”Section 1.5.6, Automatic DTR/DSR Hardware Flow Control” on
page 11. This pin has an internal pull-up resistor which is disabled during suspend
mode. If using this GPIO as an input, an external pull-up resistor is required to mini-
mize the power consumption in the suspend mode.
GPIOB3/DTRB#
19
I/O
UART Channel B general purpose I/O or UART Data-Terminal-Ready output (active
low).
See ”Section 1.5.6, Automatic DTR/DSR Hardware Flow Control”
on page 11. This pin has an internal pull-up resistor which is disabled during sus-
pend mode. If using this GPIO as an input, an external pull-up resistor is required to
minimize the power consumption in the suspend mode.
GPIOB4/CTSB#
18
I/O
UART Channel B general purpose I/O or UART Clear-to-Send input (active low).
See ”Section 1.5.5, Automatic RTS/CTS Hardware Flow Control” on
page 11. This pin has an internal pull-up resistor which is disabled during suspend
mode. If using this GPIO as an input, an external pull-up resistor is required to mini-
mize the power consumption in the suspend mode.
GPIOB5/RTSB#/
RS485B
17
I/O
UART Channel B general purpose I/O or UART Request-to-Send output (active low)
or auto RS-485 half-duplex control. See
“Section 1.5.5, Automatic RTS/CTS
Hardware Flow Control” on page 11 or “Section 1.5.8, Auto RS-485 Half-
Duplex Control” on page 12. This pin has an internal pull-up resistor which is
disabled during suspend mode. If using this GPIO as an input, an external pull-up
resistor is required to minimize the power consumption in the suspend mode.
USB Interface Signals
USBD+
30
I/O
USB port differential data plus. This pin has a 1.5 K Ohm internal pull-up resistor.
USBD-
29
I/O
USB port differential data minus.
I2C Interface Signals
SDA
25
I/O
OD
I2C-controller data input/output (open-drain). An optional external I2C EEPROM can
be used to store default configurations upon power-up including the USB Vendor ID
and Device ID. See
Table 3. A pull-up resisitor (typically 4.7 to 10k Ohms) is
required.
If an EEPROM is not used, this pin can be used with the SCL pin to select the
Remote Wake-up and Power modes. An external pull-up or pull-down resistor is
required. See
Table 2.
SCL
26
I/O
OD
I2C-controller serial input clock. An optional external I2C EEPROM can be used to
store default configurations upon power-up including the USB Vendor ID and Device
ID. See
Table 3. A pull-up resisitor (typically 4.7 to 10k Ohms) is required.
If an EEPROM is not used, this pin can be used with the SDA pin to select the
Remote Wake-up and Power modes. An external pull-up or pull-down resistor is
required. See
Table 2.
NAME
32-QFN
PIN #
TYPE
DESCRIPTION