ST STM32L4+ Series Reference Manual page 342

General-purpose I/Os (GPIO)
8.4 GPIO registers
This section gives a detailed description of the GPIO registers.
For a summary of register bits, register address offsets and reset values, refer to
The peripheral registers can be written in word, half word or byte mode.
8.4.1 GPIO port mode register (GPIOx_MODER)
(x =A to I)
Address offset:0x00
Reset value: 0xABFF FFFF (for port A)
Reset value: 0xFFFF FEBF (for port B)
Reset value: 0xFFFF FFFF (for ports C..G), I
Reset value: 0x0000 000F (for port H)
31 30 29 28
MODE15[1:0] MODE14[1:0]
rw rw rw rw
15 14 13 12
MODE7[1:0] MODE6[1:0]
rw rw rw rw
Bits 31:0 MODE[15:0][1:0]: Port x configuration I/O pin y (y = 15 to 0)
These bits are written by software to configure the I/O mode.
8.4.2 GPIO port output type register (GPIOx_OTYPER)
(x = A to I)
Address offset: 0x04
Reset value: 0x0000 0000
31 30 29 28
Res. Res. Res. Res.
15 14 13 12
OT15 OT14 OT13 OT12
rw rw rw rw
342/2301
27 26 25
MODE13[1:0] MODE12[1:0]
rw rw rw
11 10 9
MODE5[1:0] MODE4[1:0]
rw rw rw
00: Input mode
01: General purpose output mode
10: Alternate function mode
11: Analog mode (reset state)
27 26 25
Res. Res. Res.
11 10 9
OT11 OT10 OT9
rw rw rw
24 23 22
MODE11[1:0] MODE10[1:0]
rw rw rw
8 7 6
MODE3[1:0]
rw rw rw
24 23 22
Res. Res. Res. Res.
8 7 6
OT8 OT7 OT6 OT5
rw rw rw
RM0432 Rev 6
21 20 19 18
MODE9[1:0]
rw rw rw rw
5 4 3 2
MODE2[1:0] MODE1[1:0]
rw rw rw rw
21 20 19 18
Res. Res. Res.
5 4 3 2
OT4 OT3 OT2
rw rw rw rw
RM0432
Table 44.
17 16
MODE8[1:0]
rw rw
1 0
MODE0[1:0]
rw rw
17 16
Res. Res.
1 0
OT1 OT0
rw rw