MPXY8300 datasheet(49/164 Pages) FREESCALE

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MPXY8300 Series

Sensors

Freescale Semiconductor

7.3.2

KBI Pin Enable Register (KBIPE)

KBIPE contains the pin enable control bits.

7.3.3

KBI Edge Select Register (KBIES)

KBIES contains the edge select control bits.

7.4

Functional Description

This on-chip peripheral module is called a keyboard interrupt (KBI) module because originally it was designed to simplify the

connection and use of row-column matrices of keyboard switches. However, these inputs are also useful as extra external

interrupt inputs and as an external means of waking the MCU from stop or wait low-power modes.

The KBI module allows up to eight pins to act as additional interrupt sources. Writing to the KBIPEn bits in the keyboard interrupt

pin enable register (KBIPE) independently enables or disables each KBI pin. Each KBI pin can be configured as edge sensitive

or edge and level sensitive based on the KBMOD bit in the keyboard interrupt status and control register (KBISC). Edge sensitive

can be software programmed to be either falling or rising; the level can be either low or high. The polarity of the edge or edge

and level sensitivity is selected using the KBEDGn bits in the keyboard interrupt edge select register (KBIES).

Synchronous logic is used to detect edges. Prior to detecting an edge, enabled keyboard inputs must be at the reset logic level.

A falling edge is detected when an enabled keyboard input signal is seen as a logic 1 (the reset level) during one bus cycle and

then a logic 0 (the asserted level) during the next cycle. A rising edge is detected when the input signal is seen as a logic 0 during

one bus cycle and then a logic 1 during the next cycle.

KBIPE7

KBIPE6

KBIPE5

KBIPE4

KBIPE3

KBIPE2

KBIPE1

KBIPE0

Reset:

Figure 7-3 KBI Pin Enable Register

Table 7-3 KBIPE Register Field Descriptions

Field

Description

7:0

KBIPEn

Keyboard Pin Enables — Each of the KBIPEn bits enable the corresponding keyboard interrupt pin.

Pin not enabled as keyboard interrupt.

Pin enabled as keyboard interrupt.

KBEDG7

KBEDG6

KBEDG5

KBEDG4

KBEDG3

KBEDG2

KBEDG1

KBEDG0

Reset:

Figure 7-4 KBI Edge Select Register

Table 7-4 KBIES Register Field Descriptions

Field

Description

7:0

KBEDGn

Keyboard Edge Selects — Each of the KBEDGn bits selects the falling edge/low level or rising edge/high level

function of the corresponding pin).

Falling edge/low level.

Rising edge/high level.

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