STMicroelectronics STM32F05 series - GPIO Alternate Function Low Register (Gpiox_Afrl) (X = a; (X = a

General-purpose I/Os (GPIO) RM0091
132/742 Doc ID 018940 Rev 1
8.4.9 GPIO alternate function low register (GPIOx_AFRL) (x = A..B)
Address offset: 0x20
Reset value: 0x0000 0000
8.4.10 GPIO alternate function high register (GPIOx_AFRH)
(x = A..B)
Address offset: 0x24
Reset value: 0x0000 0000
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
AFRL7[3:0] AFRL6[3:0] AFRL5[3:0] AFRL4[3:0]
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
1514131211109876543210
AFRL3[3:0] AFRL2[3:0] AFRL1[3:0] AFRL0[3:0]
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
Bits 31:0 AFRLy: Alternate function selection for port x pin y (y = 0..7)
These bits are written by software to configure alternate function I/Os
AFRLy selection:
0000: AF0
0001: AF1
0010: AF2
0011: AF3
0100: AF4 (Port A only)
0101: AF5 (Port A only)
0110: AF6 (Port A only)
0111: AF7 (Port A only)
1000: Reserved
1001: Reserved
1010: Reserved
1011: Reserved
1100: Reserved
1101: Reserved
1110: Reserved
1111: Reserved
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
AFRH15[3:0] AFRH14[3:0] AFRH13[3:0] AFRH12[3:0]
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
1514131211109876543210
AFRH11[3:0] AFRH10[3:0] AFRH9[3:0] AFRH8[3:0]
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
Bits 31:0 AFRHy: Alternate function selection for port x pin y (y = 8..15)
These bits are written by software to configure alternate function I/Os
AFRHy selection:
0000: AF0
0001: AF1
0010: AF2
0011: AF3
0100: AF4 (Port A only)
0101: AF5 (Port A only)
0110: AF6 (Port A only)
0111: AF7 (Port A only)
1000: Reserved
1001: Reserved
1010: Reserved
1011: Reserved
1100: Reserved
1101: Reserved
1110: Reserved
1111: Reserved