4-16
Intel® PXA255 Processor
Developer’s Manual
System Integration Unit
4.1.3.6
GPIO Alternate Function Register (GAFR0_L, GAFR0_U, GAFR1_L,
GAFR1_U, GAFR2_L, GAFR2_U)
GAFR0_L, GAFR0_U, GAFR1_L, GAFR1_U, GAFR2_L, GAFR2_U, shown in
Table 4-24
,
Table 4-25
,
Table 4-26
,
Table 4-27
,
Table 4-28
, and
Table 4-29
, contain select bits that correspond
to the 85 GPIO pins. Each GPIO can be configured to be either a generic GPIO pin, one of 3
alternate input functions, or one of 3 alternate output functions. To select any of the alternate
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 determine which function (normal GPIO, alternate
function 1, alternate function 2 or alternate function 3) the GPIO performs. The function selected is
determined by writing the GAFR bit pair as below:
•
“00” indicates normal GPIO function
•
“01” selects alternate input function 1 (ALT_FN_1_IN) or alternate output function 1
(ALT_FN_1_OUT)
•
“10” selects alternate input function 2 (ALT_FN_2_IN) or alternate output function 2
(ALT_FN_2_OUT)
•
“11” selects alternate input function 3 (ALT_FN_3_IN) or alternate output function 3
(ALT_FN_3_OUT)
Table 4-23. GEDR2 Bit Definitions
Physical Address
0x40E0_0050
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
ED
8
4
ED
8
3
ED
8
2
ED
8
1
ED
8
0
ED
7
9
ED
7
8
ED
7
7
ED
7
6
ED
7
5
ED
7
4
ED
7
3
ED
7
2
ED
7
1
ED
7
0
ED
6
9
ED
6
8
ED
6
7
ED
6
6
ED
6
5
ED
6
4
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
<31:21>
—
reserved
<20:0>
ED[x]
GPIO Pin ‘x’ Edge Detect Status (where x=64 through 84).
READ
0 – No edge detect has occurred on pin as specified in GRER and/or GFER.
1 – Edge detect has occurred on pin as specified in GRER and/or GFER.
WRITE
0 – No effect.
1 – Clear edge detect status field.
Summary of Contents for PXA255
Page 1: ...Intel PXA255 Processor Developer s Manual January 2004 Order Number 278693 002 ...
Page 24: ...xxiv Intel PXA255 Processor Developer s Manual Contents ...
Page 30: ...1 6 Intel PXA255 Processor Developer s Manual Introduction ...
Page 310: ...7 46 Intel PXA255 Processor Developer s Manual LCD Controller ...
Page 330: ...8 20 Intel PXA255 Processor Developer s Manual Synchronous Serial Port Controller ...
Page 358: ...9 28 Intel PXA255 Processor Developer s Manual I2 C Bus Interface Unit ...
Page 488: ...13 36 Intel PXA255 Processor Developer s Manual AC 97 Controller Unit ...
Page 572: ...16 30 Intel PXA255 Processor Developer s Manual Network SSP Serial Port ...
Page 599: ...Intel PXA255 Processor Developer s Manual 17 27 Hardware UART ...
Page 600: ......