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I would like to implement a pulse-sensitive, aka edge-triggered, interrupt on an LPC1759 microcontroller. In the UM10360.pdf datasheet and ARM Cortex-M3 user guide, it says that interrupts can be triggered based on level- or pulse-sensitive behavior, but I am unable to find how to set this to be pulse-sensitive. Can someone please tell me where to set this?

For my particular application(interfacing the LPC1759 with an AD7794 ADC), I would like to trigger an interrupt based on the falling edge of the MISO pin. Although it is not explicitly stated that the interrupt is trigger on the MISO value, I am assuming this based on the fact that, of the four SPI signals, the MISO is the only input to the microcontroller. Please let me know if this is not correct.

apandit
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  • What? That doesn't make any sense. If it's an SPI link, you should leave it to the microcontroller's SPI peripheral. Don't go bit-banging stuff that you have hardware support for. – unwind May 21 '15 at 15:15
  • If you are on a slave device, the SPI peripheral can trigger an interrupt for you when you receive something. If you are on a master device, this doesn't make any sense. – ElderBug May 21 '15 at 15:18
  • Sorry...I should have mentioned that the AD7794 ADC drives the MISO line high at the beginning of a conversion and brings it low when a conversion has been completed. I would like to use the falling edge of this pulse to trigger an interrupt instead of polling for this condition. – apandit May 21 '15 at 19:01

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See UM10360.pdf, chapter 9.5.6: "GPIO interrupt registers". You can enable rising and falling edge interrupts only on port 0 and 2 pins. The interrupt vector is the same as external interrupt 3.

Turbo J
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  • Thanks Turbo J! I had been thinking along the lines of SPI interrupts and also maintaining the "SPIness" of that pin during operation so hadn't looked at that section. Apparently, you can keep the peripheral nature of that pin and still use GPIO interrupts as explained at the following link: < http://www.lpcware.com/content/forum/gpio-interrupt-peripheral-pin >. – apandit May 23 '15 at 23:17