Interrupt Generator

This is a simple interrupt generator module used for OpenRISC interrupt testing in the or1k-tests project.

See example usage in mor1kx-generic.

The intgen module provides 2 8-bit write only registers on a wishbone bus. The registers are an 8-bit counter and an interrupt clear register. The counter register at address 0x0 will decrement on every clock tick whenever the value is not zero. The interrupt line irq_o will go high when the counter reaches 1. The interrupt line is cleared when there are any writes to the interrupt clear register at address 0x1.

Diagram

            |---------------------------------------------|
            |                   INTGEN                    |
   -------->| clk_i                                       |
   -------->| rst_i                                       |
   ========>| wb_* ==\\                                   |
            |         V                                   |
            | |----REGMAP-------|                         |
            | 0x0 [ counter   ]<----(decrement if != 0)   |
            | 0x1 [ irq clear ] |                         |
            | |-----------------|                         |
            |                                             |
            |                                             |
            |           (set when counter == 1) -\        |
            |           (clear on write to irq) --- irq_o |------>
            |                                             |
            |                                             |
            |---------------------------------------------|