STMPE2401 datasheet(32/55 Pages) STMICROELECTRONICS

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GPIO controller

STMPE2401

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10.3

Hot key feature

A GPIO is known as ‘Hot Key’ when it is configured to trigger an interruption to the host

whenever the GPIO input is being asserted. This feature is applicable in Operational mode

(RC clock is present) as well as Sleep mode (32kHz clock is present).

10.3.1

Programming sequence for hot key

Configures the GPIO pin into GPIO mode by setting the corresponding bits in the

GPAFR.

Configures the GPIO pin into input direction by setting the corresponding bit in GPDR.

Set the GPRER and GPFER to the desired values to enable the rising edge or falling

edge detection.

Configures and enables the interrupt controller to allow the interruption to the host.

Now, the GPIO Expander may be put into Sleep mode if it is desired.

Upon any Hot Key being asserted, the device will wake-up and issue an interrupt to the

host.

Below are the conditions to be fulfilled in order to configure a Hot Key:

The pin is configured into GPIO mode and as input pin.

The global interrupt mask bit is enabled.

The corresponding GPIO interrupt mask bit is enabled.

10.3.2

Minimum pulse width

The minimum pulse width of the assertion of the Hot Key must be at least 62.5us. Any pulse

width less than the stated value may not be registered.

Table 30. Bit description

Bits

Name

Description

23:0

AF[x]

GPIO Pin ‘x’ Alternate Function Select (where x = 11 to 0).

‘00’ – The corresponding GPIO pin (GPIO[x]) is configured to Primary

Function.

‘01’ – The corresponding GPIO pin (GPIO[x]) is configured to Alternate

Function 1.

‘10’ – The corresponding GPIO pin (GPIO[x]) is configured to Alternate

Function 2.

‘11’ – The corresponding GPIO pin (GPIO[x]) is configured to Alternate

Function 3.

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