Intel® PXA26x Processor Family Developer’s Manual 4-17

System Integration Unit
4.1.3.6 GPIO Alternate Function Register (GAFR)

The GPIO alternate function registers (GAFR2, GAFR1, GAFR0) contain select bit s th at

correspond to the 90 GPIO pins. Each GPIO can be co nf igured to be eith er a ge ner ic GPI O pin , one

of 3 alternate input functions, or one of 3 alternate output functions. To select any of the alternate

input functions, the GPDR register must configure the GPIO to be an input. Similarly, only GPIOs

configured as outputs by the GPDR can be configured for alternate output functions. Each GPIO

pin has a pair of bits assigned to it whose values deter mine wh ich functi on ( normal G PIO, alter nate

function 1, alternate function 2 or alternate fu ncti on 3) the GP IO performs . The function select ed is

determined by writing the GAFR bit pair as below:

Table 4-22. GEDR1 Bit Definitions

Physical Address
0x40E0_004C GEDR1 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
ED63
ED62
ED61
ED60
ED59
ED58
ED57
ED56
ED55
ED54
ED53
ED52
ED51
ED50
ED49
ED48
ED47
ED46
ED45
ED44
ED43
ED42
ED41
ED40
ED39
ED38
ED37
ED36
ED35
ED34
ED33
ED32
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> ED[x]
GPIO PIN ‘X’ EDGE DETECT STATUS (where x = 32 through 63):
READ
0 – No edge detect has occurred on pin as specified in GRER or GFER.
1 – Edge detect has occurred on pin as specified in GRER or GFER.
WRITE
0 – No effect.
1 – Clear edge detect status field.

Table 4-23. GEDR2 Register Bitmap

Physical Address
0x40E0_0050 GPIO Edge Detect Status
Register2 (GEDR2) 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
Reserved
ED89
ED88
ED87
ED86
ED85
ED84
ED83
ED82
ED81
ED80
ED79
ED78
ED77
ED76
ED75
ED74
ED73
ED72
ED71
ED70
ED69
ED68
ED67
ED66
ED65
ED64
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
<31:26> — Reserved
<25:0> ED[x]
GPIO PIN ‘X’ EDGE DETECT STATUS (where x = 64 through 89):
READ
0 – No edge detect has occurred on pin as specified in GRER or GFER.
1 – Edge detect has occurred on pin as specified in GRER or GFER.
WRITE
0 – No effect.
1 – Clear edge detect status field.