System Control Module

9.1.1.3GPIO Pin Output Set Register (GPSR) and Pin Output Clear Register (GPCR)

When a port is configured as an output, the user controls the state of the pin by writing to either the GPIO pin output set register (GPSR) or the GPIO pin output clear register (GPCR). An output pin is set by writing a one to its corresponding bit within the GPSR. To clear an output pin, a one is written to the corresponding bit within the GPCR. These are write-only registers. Reads return unpredictable values. Writing a zero to any of the GPSR or GPCR bits has no effect. Writing a one to a GPSR or GPCR bit corresponding to a pin that is configured as an input has no effect. For reserved bits, writes are ignored. The following tables show the locations of the GPSR bits and the locations of the GPCR bits. These are write-only registers and reset values do not apply.

Bit

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Write

 

Reserved

 

PS27

PS26

PS25

PS24

PS23

PS22

PS21

PS20

PS19

PS18

PS17

PS16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reset

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Write

PS15

PS14

PS13

PS12

PS11

PS10

PS9

PS8

PS7

PS6

PS5

PS4

PS3

PS2

PS1

PS0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reset

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Bit

Name

 

Description

 

 

 

{n}

PS{n}

GPIO output pin set n (where n = 0 through 27).

 

 

0

– Pin level unaffected.

 

 

1

– If pin configured as an output, set pin level high (one).

 

 

 

31..28

Reserved.

 

 

 

 

Bit

Write

Reset

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reserved

 

PC27

PC26

PC25

PC24

PC23

PC22

PC21

PC20

PC19

PC18

PC17

PC16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Bit

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Write

PC15

PC14

PC13

PC12

PC11

PC10

PC9

PC8

PC7

PC6

PC5

PC4

PC3

PC2

PC1

PC0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reset

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Bit

Name

 

Description

 

 

 

{n}

PC{n}

GPIO output pin clear n (where n = 0 through 27).

 

 

0

– Pin level unaffected.

 

 

1

– If pin configured as an output, clear pin level low (zero).

 

 

 

31.. 28

Reserved.

 

 

 

 

The user can test a bit within the GPLR corresponding to a pin that is configured as an output after having set or cleared the pin state to determine if there is an external conflict on the pin. For example, if an off-chip device is driving a GPIO output pin high and the user has cleared the pin’s state by writing a one to its GPCR bit, the user can read the GPLR, then compare the written value (zero) to the actual value (one) to detect the conflict.

SA-1100 Developer’s Manual

9-5

Page 75
Image 75
Intel SA-1100 manual PS9 PS8 PS7 PS6 PS5 PS4 PS3 PS2 PS1 PS0