Global Pin Control; External Interrupts - NXP Semiconductors freescale KV4 Series Reference Manual

Table of Contents

Chapter 12 Port control and interrupts (PORT)

When the Pin Muxing mode is configured for analog or is disabled, all the digital

functions on that pin are disabled. This includes the pullup and pulldown enables, output

buffer enable, input buffer enable, and passive filter enable.

A lock field also exists that allows the configuration for each pin to be locked until the

next system reset. When locked, writes to the lower half of that pin control register are

ignored, although a bus error is not generated on an attempted write to a locked register.

The configuration of each Pin Control register is retained when the PORT module is

Whenever a pin is configured in any digital pin muxing mode, the input buffer for that

pin is enabled allowing the pin state to be read via the corresponding GPIO Port Data

Input Register (GPIO_PDIR) or allowing a pin interrupt or DMA request to be generated.

If a pin is ever floating when its input buffer is enabled, then this can cause an increase in

power consumption and must be avoided. A pin can be floating due to an input pin that is

not connected or an output pin that has tri-stated (output buffer is disabled).

Enabling the internal pull resistor (or implementing an external pull resistor) will ensure a

pin does not float when its input buffer is enabled; note that the internal pull resistor is

automatically disabled whenever the output buffer is enabled allowing the Pull Enable bit

to remain set. Configuring the Pin Muxing mode to disabled or analog will disable the

pin's input buffer and results in the lowest power consumption.

12.6.2 Global pin control

The two global pin control registers allow a single register write to update the lower half

of the pin control register on up to 16 pins, all with the same value. Registers that are

locked cannot be written using the global pin control registers.

The global pin control registers are designed to enable software to quickly configure

multiple pins within the one port for the same peripheral function. However, the interrupt

functions cannot be configured using the global pin control registers.

The global pin control registers are write-only registers, that always read as 0.

The external interrupt capability of the PORT module is available in all digital pin

muxing modes provided the PORT module is enabled.

Each pin can be individually configured for any of the following external interrupt

KV4x Reference Manual, Rev. 2, 02/2015

Freescale Semiconductor, Inc.