arm,armv8.1m-systick

Description

ARMv8.1-M System Tick

Properties

Properties not inherited from the base binding file.

Name

Type

Details

external-clock-source

boolean

 
For ARM Cortex-M SysTick timer, the CLKSOURCE bit in the
SysTick Control and Status Register (CSR) selects the clock source.
If this property is present, the external reference clock is selected.
If absent, the processor/core clock is selected.

zephyr,min-timeout-cycles

int

 
Minimum SysTick timeout, in SysTick cycles. This is the smallest value the
SysTick driver will program into the timer LOAD register. It determines the
kernel's minimum available timing granularity (resolution) in conjunction
with the clock frequency (CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC).

When specified, the minimum timing granularity is
(<value> cycles / CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC) seconds.
Otherwise, the default is MAX(1024, CYC_PER_TICK / 16) cycles, where
CYC_PER_TICK = CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC /
CONFIG_SYS_CLOCK_TICKS_PER_SEC.

For example, if CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=32768 and
CONFIG_SYS_CLOCK_TICKS_PER_SEC=1000, CYC_PER_TICK equals 32 cycles.
In this case, the default MIN_DELAY is MAX(1024, 32/16) = 1024 cycles,
which corresponds to ~31.25 ms. This might be too coarse for many use
cases. Setting this property to 32 (zephyr,min-timeout-cycles = <32>;)
results in a minimum timing granularity of (32 / 32768) seconds (~1 ms)
instead.