STMPE1600

GPIO controller

Doc ID 16938 Rev 3

17/27

8

GPIO controller

A total of 16 GPIOs are available in the STMPE1600 port expander IC. The GPIO controller

contains the registers that allow the host system to configure each of the pins into either a

GPIO (input or output), or into one of the alternate functions. Unused GPIOs should be

configured as outputs to minimize the power consumption.

A group of registers are used to control the exact function of each of the 16 GPIOs. The

registers and their respective address are listed in the following table.

Note:

Once the last register address 0x16-0x17 location is accessed, the locations of 0x18 to

0xFF are reserved. After 0xFF location, the pointer rolls over to the 0x00 register address

location.

All GPIO registers are named as GPxx, where:

xx represents the functional group.

The function of each bit is shown in the following table:

On power-up reset, all GPIOs are set as input.

Table 8.

GPIO controller registers

Address

Register name

Description

Auto-increment

(during sequential

R/W)

0x10

GPMR

GPIO monitor pin state

register

Yes

0x12

GPSR

GPIO set pin state

register

Yes

0x14

GPDR

GPIO set pin direction

register

Yes

0x16

GPPIR

GPIO polarity inversion

register

Yes

15

14

13

12

11

10

9

876543

2

1

0

IO-15 IO-14 IO-13 IO-12 IO-11 IO-10

IO-9

IO-8

IO-7

IO-6

IO-5

IO-4

IO-3

IO-2

IO-1

IO-0

Table 9.

GPIO bit function

Register name

Function

GPIO monitor pin state

Reading this bit yields the current state of the bit. Writing has no effect.

GPIO set pin state

Writing ‘1’ to this bit causes the corresponding GPIO to go to ‘1’ state.

Writing ‘0’ to this bit causes the corresponding GPIO to go to ‘0’ state.

GPIO set pin direction

‘0’ sets the corresponding GPIO to input state, and ‘1’ sets it to output

state. All bits are ‘0’ on reset.

GPIO polarity inversion

Writing a ‘1’ enables polarity inversion on the Input Port.

Writing a ‘0’, the input port polarity is retained. The reset value is 0.