nios custom ip interrupt questions.

Altera_Forum · ‎06-15-2015

hi, everyone, i am new to nios and i have some questions about coustom ip interrupt.

my nios' frequence is 100MHz, in my custom ip, i creat a irq signal that last for 10 clk periods, in debug mode, the interrupt failed, the code can not go into the interrupt handler. then i change the irq signal, make it last 128 clk periods, then the interrupt works.

i have some questions:

1. how long should the irq signal last?

2. how the irq works, edge trigger or level trigger?

if it is edge trigger, why my interrupt failed if it only last for 10 clk periods?

if it is level trigger, my irq signal last 127 clk periods, will it cause another interrupt before my interrupt handler finish?

thanks

Altera_Forum · ‎06-15-2015

https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/manual/mnl_avalon_spec.pdf

See Chapter 4 Avalon Interrupt Interfaces.

--- Quote Start ---

4.1 Interrupt Sender

An interrupt sender drives a single interrupt signal to an interrupt receiver. The timing of the

irq signal must be synchronous to the rising edge of its associated clock. irq has no relationship

to any transfer on any other interface. irq must be asserted until acknowledged

on the associated Avalon-MM slave interface.

--- Quote End ---