X221, -LC, -AI
TECHNICAL REFERENCE MANUAL
VERSION: 1.4
Page 12 of 38
4.2.4
Pinout basic MCU
STM32L031G6U6TR
Pin
Description
Socket pin
Note
1
3V3_AO
3.3V
2
MCU_LED
5V tolerant
3
ForceRec
4
MCU_RESET
With 3.3V pullup
5
3V3_AO
3.3V
6
EFM8_BUTTON_POWER_ON*
7
EFM8B10_D_ONKEY_N
8
PA6
9
EFM8_ACOK
10
EFM8_PSHOLD
11
EFM8_FORCE_SHUTDOWN
12
EFM8_RST_MON
13
PA7
USB0_VBUS/2
14
/PFO
15
SYS_RST
16
GND
17
3V3_AO
3.3V
18
3V3_AO
3.3V
19
MCU_TX
Connected to J14 pin 2
20
MCU_RX
Connected to J14 pin 3
21
SWDIO
Connected to J14 pin 5
22
SWCLK
Connected to J14 pin 4
23
USB0_EN
24
EFM8_VIN_PWER_ON
25
EFM8_MODULE_POWER_ON
26
EFM8_POWER_BTN_ON*
27
BOOT0
28
GND