Simplified Interrupt Controller
- smokku
The Interrupt Controller got significantly simplified.
@willy on Discord noticed that my design of using I²C GPIO extender chips as the interrupt controller
might be a bad idea. The I²C bus, even running at 400 kHz, is way too slow to react as a memory-mapped device.
This might work for write-mostly devices like the Audio Mixer we use, as writes can be fire’n’forget,
but waiting for such a slow read is unacceptable for interrupt latency.
I’ve decided to rethink and really simplify interrupt handling.
Having two places to ACK interrupts (source + controller) was getting annoying already.
The current design consists of simply a NAND gate joining all the signals,
and yet another bus transceiver to read all interrupt sources in one go.
Well… I guess there is not much of a “controlling” aspect left. No masking, no ACKing.
The advantage is that it is really simple to use though.