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Intel® PXA255 Processor Developer’s Manual 4-17
System Integration Unit
Caution: Configuring a GPIO to map to an alternate function that is not available causes indeterminate
results.
Table 4-24. GAFR0_L Bit Definitions
Physical Address
0x40E0_0054
GAFR0_L System Integration Unit
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
AF15 AF14 AF13 AF12 AF11 AF10 AF9 AF8 AF7 AF6 AF5 AF4 AF3 AF2 AF1 AF0
Reset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits Name Description
<31:0> AF[x]
GPIO Pin ‘x’ Alternate Function Select Bits (where x=0 through 15).
A bit-pair in this register determines the corresponding GPIO pin’s functionality as one of
the alternate functions that is mapped to it or as a generic GPIO pin.
00 – The corresponding GPIO pin (GPIO[x]) is used as a general purpose I/O.
01 – The corresponding GPIO pin (GPIO[x]) is used for its alternate function 1.
10 – The corresponding GPIO pin (GPIO[x]) is used for its alternate function 2.
11 – The corresponding GPIO pin (GPIO[x]) is used for its alternate function 3.
Table 4-25. GAFR0_U Bit Definitions
Physical Address
0x40E0_0058
GAFR0_U System Integration Unit
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
AF31 AF30 AF29 AF28 AF27 AF26 AF25 AF24 AF23 AF22 AF21 AF20 AF19 AF18 AF17 AF16
Reset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits Name Description
<31:0> AF[x]
GPIO Pin ‘x’ Alternate Function Select Bits (where x=16 through 31).
A bit-pair in this register determines the corresponding GPIO pin’s functionality as one of
the alternate functions that is mapped to it or as a generic GPIO pin.
00 – The corresponding GPIO pin (GPIO[x]) is used as a general purpose I/O.
01 – The corresponding GPIO pin (GPIO[x]) is used for its alternate function 1.
10 – The corresponding GPIO pin (GPIO[x]) is used for its alternate function 2.
11 – The corresponding GPIO pin (GPIO[x]) is used for its alternate function 3.