ST STM32F446 Series

General-purpose I/Os (GPIO) RM0390
192/1328 RM0390 Rev 4
7.4.9 GPIO alternate function low register (GPIOx_AFRL) (x = A..H)
Address offset: 0x20
Reset value: 0x0000 0000
7.4.10 GPIO alternate function high register (GPIOx_AFRH) (x = A..H)
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]
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1514131211109876543210
AFRL3[3:0] AFRL2[3:0] AFRL1[3:0] AFRL0[3:0]
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Bits 31:0 AFRLy: Alternate function selection for port x bit 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
0101: AF5
0110: AF6
0111: AF7
1000: AF8
1001: AF9
1010: AF10
1011: AF11
1100: AF12
1101: AF13
1110: AF14
1111: AF15
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]
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1514131211109876543210
AFRH11[3:0] AFRH10[3:0] AFRH9[3:0] AFRH8[3:0]
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Bits 31:0 AFRHy: Alternate function selection for port x bit 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
0101: AF5
0110: AF6
0111: AF7
1000: AF8
1001: AF9
1010: AF10
1011: AF11
1100: AF12
1101: AF13
1110: AF14
1111: AF15