STM32: Bad value returned by systick.get_time_since_boot().to_us()

Hi, Calling `systick.get_time_since_boot().to_us()` will occasionally return a bad value every 50s or so. HW: STM32 F3 Discovery board Using Microzig release 0.15.1 Compiling with zig 0.15.2 main.zig: ``` const std = @import("std"); const microzig = @import("microzig"); const hal = microzig.hal; const board = microzig.board; const log = std.log; pub const microzig_options: microzig.Options = .{ .logFn = microzig.board.uart_logger.log, .cpu = .{ .ram_vector_table = true, }, .hal = .{ .rcc_clock_config = board.rcc_medium_speed } }; pub fn init() void { hal.dma.DMA1_Channel4.enable_interrupt(); board.init(); board.init_log(); hal.systick.init() catch { @panic("systick init fail"); }; } pub fn main() !void { const systick = hal.systick_timer.clock_device() catch { @panic("systick_timer clock device"); }; var last_us: u64 = systick.get_time_since_boot().to_us(); while (true) { const now_us = systick.get_time_since_boot().to_us(); if (now_us > last_us + 20_000) { const now2_us = systick.get_time_since_boot().to_us(); log.info("now_us jump={d}us last_us={d}us now_us={d}us now2_us={d}us", .{now_us - last_us, last_us, now_us, now2_us}); } last_us = now_us; } } ``` build.zig: ``` const std = @import("std"); const microzig = @import("microzig"); const MicroBuild = microzig.MicroBuild(.{ .stm32 = true, }); pub fn build(b: *std.Build) void { const mz_dep = b.dependency("microzig", .{}); const mb = MicroBuild.init(b, mz_dep) orelse return; const firmware = mb.add_firmware(.{ .name = "firmware", .target = mb.ports.stm32.boards.stm32f3discovery, .optimize = .Debug, .root_source_file = b.path("src/main.zig"), }); mb.install_firmware(firmware, .{}); mb.install_firmware(firmware, .{ .format = .elf }); const flash_argv = [_][] const u8 { "arm-none-eabi-gdb.exe", "-iex", "set auto-load safe-path /", "--batch", "--quiet", "--command=flash.gdb", }; const flash_cmd_step = b.addSystemCommand(&flash_argv); flash_cmd_step.step.dependOn(b.getInstallStep()); const flash_step = b.step("run", "Flash FW to board"); flash_step.dependOn(&flash_cmd_step.step); } ``` Output: ``` info: ================ STARTING NEW LOGGER ================ info: now_us jump=2785286us last_us=8355833us now_us=11141119us now2_us=8355846us info: now_us jump=2785285us last_us=30638074us now_us=33423359us now2_us=30638087us info: now_us jump=2785285us last_us=75202554us now_us=77987839us now2_us=75202567us info: now_us jump=2785285us last_us=119767034us now_us=122552319us now2_us=119767047us info: now_us jump=2785286us last_us=125337593us now_us=128122879us now2_us=125337606us info: now_us jump=2785285us last_us=175472634us now_us=178257919us now2_us=175472647us info: now_us jump=2785286us last_us=181043193us now_us=183828479us now2_us=181043206us info: now_us jump=2785285us last_us=231178234us now_us=233963519us now2_us=231178247us info: now_us jump=2785286us last_us=236748793us now_us=239534079us now2_us=236748806us info: now_us jump=2785285us last_us=286883834us now_us=289669119us now2_us=286883847us info: now_us jump=2785286us last_us=292454393us now_us=295239679us now2_us=292454406us info: now_us jump=2785285us last_us=342589434us now_us=345374719us now2_us=342589447us info: now_us jump=2785286us last_us=348159993us now_us=350945279us now2_us=348160006us info: now_us jump=2785285us last_us=398295034us now_us=401080319us now2_us=398295047us info: now_us jump=2785286us last_us=403865593us now_us=406650879us now2_us=403865606us info: now_us jump=2785285us last_us=454000634us now_us=456785919us now2_us=454000647us info: now_us jump=2785286us last_us=459571193us now_us=462356479us now2_us=459571206us ``` Thanks!