File syn_timesync.c¶

FileList > drivers > syn_timesync.c

High-precision time discipline and clock synchronization implementation.

#include "../util/syn_assert.h"
#include "syn_timesync.h"
#include <stdlib.h>
#include <string.h>

Public Functions¶

Type	Name
SYN_Status	syn_timesync_bind_pps (SYN_TimeSync * tsync, const SYN_HPTimestamp * pps_ts, uint64_t utc_sec) Bind a captured PPS timestamp to its corresponding UTC second.
void	syn_timesync_init (SYN_TimeSync * tsync) Initialize a time discipline context.
bool	syn_timesync_is_pps_locked (const SYN_TimeSync * tsync) Check if active PPS lock is present.
SYN_Status	syn_timesync_resolve_utc (const SYN_TimeSync * tsync, const SYN_HPTimestamp * event_ts, SYN_UTCTimestamp * out_utc) Resolve an arbitrary high-precision timestamp into UTC.
uint64_t	syn_timesync_to_epoch_ns (const SYN_TimeSync * tsync, const SYN_HPTimestamp * event_ts) Helper: resolve event timestamp directly to total 64-bit UTC nanoseconds.

Public Functions Documentation¶

function syn_timesync_bind_pps¶

Bind a captured PPS timestamp to its corresponding UTC second.

SYN_Status syn_timesync_bind_pps (
    SYN_TimeSync * tsync,
    const SYN_HPTimestamp * pps_ts,
    uint64_t utc_sec
)

Call this when an asynchronous epoch time sentence (e.g. NMEA $GPZDA) is received, pairing the integer UTC second with the PPS timestamp captured at the top of that second.

Measures crystal drift PPM against nominal syn_port_hpclock_freq_hz().

Parameters:

tsync TimeSync context. Must not be NULL.
pps_ts Timestamp snapshot captured by ISR at PPS rising edge.
utc_sec Universal UTC epoch second corresponding to this PPS pulse.

Returns:

SYN_OK on success, SYN_INVALID_PARAM if pps_ts is NULL.

function syn_timesync_init¶

Initialize a time discipline context.

void syn_timesync_init (
    SYN_TimeSync * tsync
)

Sets default jitter (50 ns) and max holdover (60 s). If hardware RTC is enabled (SYN_USE_RTC), checks if the RTC is valid.

Parameters:

tsync Context to initialize. Must not be NULL.

function syn_timesync_is_pps_locked¶

Check if active PPS lock is present.

bool syn_timesync_is_pps_locked (
    const SYN_TimeSync * tsync
)

Parameters:

tsync TimeSync context.

Returns:

true if PPS lock is active (received within last 1.1s).

function syn_timesync_resolve_utc¶

Resolve an arbitrary high-precision timestamp into UTC.

SYN_Status syn_timesync_resolve_utc (
    const SYN_TimeSync * tsync,
    const SYN_HPTimestamp * event_ts,
    SYN_UTCTimestamp * out_utc
)

Converts a raw SYN_HPTimestamp (captured in an ISR or main thread) into absolute UTC time, calculating the sub-second offset, active quality tier, and linear error accumulation bound (uncertainty_ns).

Handles event timestamps occurring before or after the reference PPS pulse.

Parameters:

tsync TimeSync context. Must not be NULL.
event_ts Event timestamp to resolve. Must not be NULL.
out_utc Output UTC timestamp. Must not be NULL.

Returns:

SYN_OK on success, SYN_INVALID_PARAM if args are NULL.

function syn_timesync_to_epoch_ns¶

Helper: resolve event timestamp directly to total 64-bit UTC nanoseconds.

uint64_t syn_timesync_to_epoch_ns (
    const SYN_TimeSync * tsync,
    const SYN_HPTimestamp * event_ts
)

Parameters:

tsync TimeSync context.
event_ts Event timestamp to resolve.

Returns:

Total nanoseconds since Unix epoch (1970-01-01 00:00:00 UTC).

The documentation for this class was generated from the following file src/syntropic/drivers/syn_timesync.c