PINT General description

Pins with configurable functions can serve as external interrupts or inputs to the pattern match engine. You can configure up to eight pins total using the PINTSEL registers in the SYSCON block for these features.

Pin interrupts

From all available GPIO pins, up to eight pins can be selected in the system control block to serve as external interrupt pins (see Pattern match bit slice with detect logic). The external interrupt pins are connected to eight individual interrupts in the NVIC and are created based on rising or falling edges or on the input level on the pin.

n = 6 for the DIP8 package, n= 14 for the TSSOP16/XSON16 package, n = 18 for the TSSOP/SOP20 packages.

Pin interrupt connections

Pattern match engine

The pattern match feature allows complex boolean expressions to be constructed from the same set of eight GPIO pins that were selected for the GPIO pin interrupts. Each term in the boolean expression is implemented as one slice of the pattern match engine. A slice consists of an input selector and a detect logic. The slice input selector selects one input from the available eight inputs with each input connected to a pin by the input’s PINTSEL register.

The detect logic monitors the selected input continuously and creates a HIGH output if the input qualifies as detected. Several terms can be combined to a minterm by designating a slice as an endpoint of the expression. A pin interrupt for this slice is asserted when the minterm evaluates as true.

See for the detect logic block.

Pattern match engine connections

The detect logic of each slice can detect the following events on the selected input:

  • Edge with memory (sticky): A rising edge, a falling edge, or a rising or falling edge that is detected at any time after the edge-detection mechanism has been cleared. The input qualifies as detected (the detect logic output remains HIGH) until the pattern match engine detect logic is cleared again.
  • Event (non-sticky): Every time an edge (rising or falling) is detected, the detect logic output for this pin goes HIGH. This bit is cleared after one clock cycle, and the detect logic can detect another edge,
  • Level: A HIGH or LOW level on the selected input.

Pattern match bit slice with detect logic shows the details of the edge detection logic for each slice.

You can combine a sticky event with non-sticky events to create a pin interrupt whenever a rising or falling edge occurs after a qualifying edge event.

You can create a time window during which rising or falling edges can create a pin interrupt by combining a level detect with an event detect. See PINT Pattern match engine edge detect examples for details.

Pattern match bit slice with detect logic