WM8351 datasheet(184/330 Pages) WOLFSON

184 / 330 page

WM8351

Production Data

PD, April 2012, Rev 4.5

184

20.2.2

SELECTING GPIO ALTERNATE FUNCTIONS

The function of each GPIO pin is programmable by writing to the respective GPn register bits.

GPn_FN = 0000 selects the GPIO function and settings other than 0000 select various alternate

functions.

The GPIO function is also determined by the value of the GPn_DIR register bit. Note that, when

changing GPn_DIR, it is recommended to set GPn_FN = 0000 first.

When changing the function of a GPIO pin, (updating GPn_FN or GPn_DIR), it is recommended that

the following sequence of actions is taken sequentially.



Set GPn_FN = 0000



Update the other GPIO configuration fields GPn_DB, GPn_PU, GPn_PD, GPn_CFG, GPn_DIR



If the new function is an input, ensure that the input trigger is in the inactive state (ie. logic 0 for a

function that is active High)



Set GPn_FN according to the new GPIO function



Read the GPIO Interrupt Status Register R30 (1Eh) to clear any GPIO Interrupt events



If any bit in Register R30 (1Eh) was set when read, then read the System Interrupts Register

R24 (18h) to clear the IRQ pin

Note that GPIO7 is automatically enabled as CSB in 3-wire and 4-wire control modes. GPIO6 is

automatically enabled as SDOUT in 4-wire control mode. These automatic selections take

precedence over all other GPIO6 and GPIO7 control fields.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R140 (8Ch

GPIO function

select 1

3:0

GP0_FN

Depends

on status

of CONF

pins

Selects function of GPIO0

7:4

GP1_FN

Selects function of GPIO1

11:8

GP2_FN

Selects function of GPIO2

15:12

GP3_FN

Selects function of GPIO3

R141 (8Dh)

GPIO function

select 2

3:0

GP4_FN

Selects function of GPIO4

7:4

GP5_FN

Selects function of GPIO5

11:8

GP6_FN

Selects function of GPIO6

15:12

GP7_FN

Selects function of GPIO7

R142 (8Eh)

GPIO function

select 3

3:0

GP8_FN

Selects function of GPIO8

7:4

GP9_FN

Selects function of GPIO9

11:8

GP10_FN

Selects function of GPIO10

15:12

GP11_FN

Selects function of GPIO11

R143 (8Fh)

3:0

GP12_FN

Selects function of GPIO12

Table 125 Control Registers to Select GPIO Alternate Functions

WM8351 Datasheet(PDF) 184 Page - Wolfson Microelectronics plc

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