DT Elapsed Timer Question

[richard]

I can't see significant difference in overhead between say this and the elapsed timer example

correct there is not much overhead difference when pbp interrupts are used , main point was to show that time accuracy using time stamps is easy versus trying to fudge clock counts
so that elapsed_int could be used without modification and also to show that conversion to h:m:s is not too difficult

the main difference between asm and pbp interrupts is whats entailed in ReEnterPBP.bas code . its up to the user to determine if the application can tolerate the overhead or a more efficient method need be developed

[rocket_troy]

So, if I was to make an interrupt routine that only incremented a... say 16 bit variable - say 3 or 4 lines of assembler and that's all it did - would I be risking too much to not back up the system variables?

[richard]

if your isr's only use asm code then there is no need to back up any pbp working registers at all , mcu context must always be saved and restored in the isr process. most advanced core pic's have auto context save/restore otherwise that need to be added to the isr process too, refer to your datasheet

[rocket_troy]

Thanks again Richard. I might have crack at a bleeding minimum overhead routine over the weekend and see what happens.