Why is PINGETZ/RDPIN/whatever not an implicit PINACK?

Seairth

I can understand needing a separate ACK instruction for when you don't need to read from the pin (e.g. serial tx). But, is there a reason you would not want to ACK a pin when you read it?

ozpropdev

Maybe because multiple cogs can all do a PINGETZ (RDPIN) from any smartpin even if they didn't configure it in the first place.

evanh

Multiple Cogs, that aren't synchronised, reading one Smartpin would have some messy gotchas I'd think. On that note, it would make quite good sense for a RDPIN to reset the IN signal.

ozpropdev

From another thread "Shared Smartpins" Chip said

All cogs can simultaneously do PINGETZ on the same pin, but PINSETx/PINACK to the same pin cannot be from multiple cogs at once

jmg

Seairth wrote: »

I can understand needing a separate ACK instruction for when you don't need to read from the pin (e.g. serial tx). But, is there a reason you would not want to ACK a pin when you read it?

I think this could vary with MODE.

For simple data-flow, as in the new DAC-Path, it makes sense to ACK-on-Read.

However, with hardware pin actions, there is a limited signaling set between COG and PIN, and some means to separately READ and Re-Arm could be needed with HW Pin Cell use.