MPR083

Sensors

Freescale Semiconductor

19

Preliminary

7

Interrupts

7.1

Introduction

The MPR083 has one interrupt output that is configured by registers and alerts the application when a touch or fault is detected.

7.2

Condition for Interrupt

There are two cases that latch the Interrupt buffered data available or fault detected.

7.2.1

Buffered Data Available

The interrupt for Buffered Data Available will only trigger when the NDF (No Data Flag) transitions from high to low. This signifies

that there is new data available in the buffer. The interrupt is deasserted on the first read/write of the FIFO Register and cannot

be reasserted for buffered data until the FIFO is empty (either by reading all the data, or clearing the buffer).

7.2.2

Fault Detected

The interrupt for a fault detected condition is triggered any time the Fault condition in the Fault Register transitions from zero to

non-zero. The interrupt is deasserted when the Fault Register is cleared (by writing to the Fault Register).

7.3

Settings

the interrupt functionality.

The Interrupt Enable (IRQEN) must be set high for the IRQ to be enabled. When low, all interrupts will be ignored, and the IRQ

pin will never latch.

The Interrupt Rate (IRQR) sets the minimum delay between sequential triggered interrupts. The minimum interrupt period can be

calculated by taking the product of the (MTP + 5) and IRQR with a factor of 4. Thus, for the minimum setting an interrupt would

be triggered no more often than 4 times the master clock.

Equation 4

If the MPR083 is using Run2, the minimum interrupt period would be represented by the following equation.

Equation 5

7.4

IRQ Pin

The IRQ pin is an open-drain, latching interrupt output which requires an external pull-up resistor. The pin will latch down based

information about the source of the interrupt. Thus if the source is buffered data available then a FIFO Buffer read/write will clear

the IRQ pin. If the source is a fault detected then a write of the Fault Register will clear the pin.

MinInterruptPeriod ms

()

MTP

5

+

() IRQR

×

4

×

=

MinInterruptPeriod ms

()

MTP

5

+

8

----------------------

1

+

⎝⎠

⎛⎞

8

I

× RQR 4

×

×

=