posts/delta_lists_for_timers/

[utterances-bot]

Optimizing Timer Management in Embedded Systems with Delta Lists | Pyjama Brah!

Looking for and exposing the insights - from AI down to the Transistor!

https://pyjamabrah.com/posts/delta_lists_for_timers/

[Shubhamyadav7]

Correct me if I am wrong but when you say:
The first timer (5 ms) expires.
The next timer’s delta is adjusted by subtracting the expired timer’s value:
Updated list → [7 - 5, 6] → [2 ms, 6 ms]
The next timer (2 ms) expires, updating the list further.

Wont this mean that the second timer will expire at 7ms instead of the desired 12ms ?

[streetdogg]

First should expire at 5ms, the second +7ms from it (at 12ms) and then then next one at 6ms delta, which will be at 18ms.

What is being stored as a list is the delta to the expiry from the 0th time - So read it as
from 0ms expire at [+5ms, +7ms, +6ms] respectively...

[Shubhamyadav7]

Yes I agree with this part, but under "How the Delta List Updates" its written that:

The next timer’s delta is adjusted by subtracting the expired timer’s value:
Updated list → [7 - 5, 6] → [2 ms, 6 ms]
The next timer (2 ms) expires, updating the list further.

Does this mean that timer2 should expire at +2ms from t=5ms (5ms is when the first timer expired, and the Delta list got updated)

[neeraj1397]

Remember at any given time, the delta list stores the timer values (all running in parallel) from zeroth instance at that point of time. So ot appears that the second timer is expiring at 7ms since all the timers in the list should run in parallel.

[FookinAshura]

Can anyone tell that are we using the same timer HW with different elapse time for different purpose / different timers HW here?

[streetdogg]

You can have a single timer fire every 1ms and check if the time expired for the first task. If it did, then fire the callback and continue ticking.

[irq-ops]

I have written software timer implementation based on delta list. check it out at https://github.com/irq-ops/Software-Timer-. feedback is greatly appreciated

[streetdogg]

Good one.

[freeman1216]

Updated list → [7 - 5, 6] → [2 ms, 6 ms]
The next timer (2 ms) expires, updating the list further.

the whole point of the delta list is to NOT DO THAT, thanks ai generated slop