Rust async and the ARM generic timer
The article discusses the implementation of timers in Rust for the Arm architecture, focusing on the Arm SYSTICK and CMSDK timers. It highlights the limitations of the SYSTICK timer for long-duration events and introduces the CMSDK timer as a more capable alternative. The article aims to provide insights into running concurrent tasks on Arm processors using these timers.
- ▪The Arm SYSTICK timer is a standard feature in all Arm Cortex-M devices, designed primarily for generating regular interrupts.
- ▪The SYSTICK timer has a 24-bit counter, limiting its maximum wait time to approximately 34.95 ms with a 480 MHz system clock.
- ▪The Arm CMSDK timer offers a 32-bit counter and is more suitable for setting alarms for variable future events.
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JP's Website Scroll through the blog: ‹ Newer | List All | Older › Finding the Time Part 2 - Rust Async and the Arm Generic Timer Posted on 2026-05-17 Contents Intro Timers Arm SYSTICK Arm CMSDK Timer Arm Generic Timer Embassy RTIC Intro In the last article, I set out the various versions of the Arm Architecture, and ones I've been focussed on whilst developing the aarch32-rt and aarch32-cpu libraries. Building an example that gets into fn main() and perhaps fires a few interrupts is fine and all that, but most people using these big processors are going to want a bit more - some sort of framework that lets them run multiple tasks concurrently (whether using pre-emptive task switching, or co-operative scheduling) and manage a list of upcoming events (like timeouts, or when the LED next…
Excerpt limited to ~120 words for fair-use compliance. The full article is at JP's Website.
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