[Milkymist-devel] LM32 interrupts

[Sébastien Bourdeauducq]

The interrupt controller in LM32 is definitely edge-sensitive, so its 
documentation is wrong:

(from lm32_interrupt.v):

(...)
input [interrupts-1:0] interrupt_n;             // Interrupt pins, active-low
(...)
// Determine which interrupts are currently being asserted (active-low) or are 
// already pending
assign asserted = ip | ~interrupt_n;
(...)
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
(...)
ip <= asserted;
(...)
if (csr == `LM32_CSR_IP)
	ip <= asserted & ~csr_write_data[interrupts-1:0];
(...)

I am also wondering why they use active low signals? From this design, they do 
not seem to provide any architectural advantage, and only make using LM32 a 
bit more complex...

Sébastien