threadx_systick_retune Directory Reference

Directory dependency graph for threadx_systick_retune:

Directories
	src

Detailed Description

Proves the ThreadX kernel tick stays 1 ms whatever CPUCLK0 the app happened to boot at (#287).

tx_initialize_low_level.S programs SysTick.LOAD from a compile-time clock assumption – the post-CGC CPUCLK0 target. That is only correct if the app raised CPUCLK0 to exactly that rate before tx_kernel_enter(). Enter the kernel on the boot-default MOCO instead and the nominal 1 ms tick runs scaled by the clock ratio, two orders of magnitude slow, silently stretching every tx_thread_sleep and every timer.

ra8_threadx_systick_retune(), called from tx_application_define, re-derives SysTick.LOAD from the live CPUCLK0 rate reported by ra8_cgc_get_clock_hz, so the tick is right regardless of clock. A live clock too fast for the 24-bit SYST_RVR returns an error rather than truncating.

A worker thread toggles LED1 (P600, EK-RA8D2 v1 UM Table 24 p 31) and bumps a liveness counter. The app also recomputes the expected reload independently and reads SYST_RVR back, raising a failure flag if the two disagree; a J-Link memprobe watches both. The SYST_RVR write lands in the emulated System Control Space as well, so the emulator runs the identical ARM path and its verdict matches the on-hardware one.

No per-app SysTick_Handler override is needed: the shared weak handler in libs/ra8_core already dispatches to _tx_timer_interrupt (#8), and PendSV_Handler / SVC_Handler arrive as strong symbols from the upstream ThreadX port.