Product Manual

XR3 Datasheet
7
Pin No.
Symbol
I/O Type
Function
5
PA22
I/O
PA22
6
PA21
I/O
PA21
7
PA20
I/O
PA20
8
VCC
P
Power input pin (3.3 V)
9
PA16
I/O
PA16
10
PA07
I/O
PA07
11
GND
P
Power supply reference ground pin
12
PA06
I/O
PA06
13
PA15
I/O
PA15
14
PA14
I/O
PA14
15
GND
P
Power supply reference ground pin
16
PA12
I/O
PA12
17
RXD0
I/O
Can be used as a debugging serial interface pin，
connect with UART-RX
18
TXD0
I/O
Can be used as a debugging serial interface pin，
connect with UART-TX
19
PB03
I/O
PB03 (PB03 and PB02 cannot be pulled down
simultaneously.)
20
PA19
I/O
PA19
21
RXD
I/O
User UART_RX，connect with UART-TX
22
TXD
I/O
User UART_TX，connect with UART-RX
Note:
1. P indicates power supply pins, I/O indicates input/output pins, and AI indicates analog
input pins.
2. This Pin2 can be used as an ADC input. If this pin is not used, it must be
disconnected. When this pin is used as an ADC input, the input voltage range is 0 V to
2.5 V.
3. During firmware burning, both PB02 and PB03 need to be connected to a low level.
When the module works properly, PB02 and PB03 cannot be connected to a low level