configEdgeExint

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Description

Function to set the edge sensitivity for the external port interrupt (EXINT). Note that for port interrupts, all 8 port pins share the same edge sensitivity.

Notes:

• after reset edge sensitivity of all ports is LOW. To avoid stalling the device in case of a static low pin, change edge sensitivity prior to enabling the external interrupt.
• to enable an external interrupt, the respective pin has be configured as INPUT_INTERRUPT or INPUT_PULLUP_INTERRUPT via pinMode() or portMode()

Inclusion

• defined in gpio.h
• auto-loaded in main_general.h
• in config.h set #define USE_PORTx_ISR (x=A..F) for the respective GPIO port. For each activated port, a respective interrupt service routine PORTx_ISR() is required.
• for the TLI capable pin, e.g. PD7, use command configEdgeTLI() and TLI_ISR() instead

Syntax

configExintEdge(pPort, sensitivity);

Parameters

• input:

  • pPort: address of port to configure, e.g. &PORT_A
  • sensitivity: edge sensitivity to set
    • LOW : EXINT on low level. Warning: can stall device on pin static low
    • CHANGE : EXINT on both edges
    • RISING : EXINT on rising edge
    • FALLING : EXINT on falling edge

• output:

  • none

Returns

• nothing

Example Code

The below code counts the number of falling edges on pin PE5 (without debounce).

#include "main_general.h"

uint16_t   count=0;

ISR_HANDLER(PORTE_ISR, __PORTE_VECTOR__) {
  count++;
}

void setup()
{
  noInterrupts();
  configEdgeExint(&PORT_E, FALLING);
  pinMode(&PORT_E, 5, INPUT_PULLUP_INTERRUPT);
  interrupts(); 
}

void loop()
{
  // dummy
}

Relevant Tutorial

• General_Examples/Port_Interrupt

Notes and Warnings

• before changing the edge sensitivity, globally disable interrupts via noInterrupts(). Re-enable them afterwards via interrupts().
• to use EXINTs the respective pins must also be configured as INPUT_INTERRUPT or INPUT_PULLUP_INTERRUPT via pinMode() or portMode()
• use port edge sensitivity LOW with care, e.g. disable EXINT in ISR. Else a port pin with static low level can stall the device

To avoid damage

• do not expose I/Os to voltages outside [-0.3V; Vdd+0.3V], else limit injection currents to the specificied limits
• for OUTPUT pins assert that sink and source currents are below the specificied limits
• do not directly connect two OUTPUT pins. If e.g. half-duplex is required, use a pull-up and OUTPUT_OPENDRAIN, instead

See also

• pinMode()
• portMode()
• pinLow()
• pinHigh()
• pinToggle()
• pinSet()
• pinRead()
• pinOutputReg()
• pinInputReg()
• portOutputReg()
• portInputReg()
• configEdgeTLI()