Server Time Sources

TinyCTSServer::begin() takes a TinyCTSTimeSource: an object that knows the current UTC time in milliseconds since 1970-01-01. While getTimeMs() returns 0 (time not known), the server reports a Current Time with an unknown date.

Class	Time from
TinyCTSClockSource	A software clock that you set (RTC, GPS, ...) and that counts with millis()
TinyCTSSystemSource	The system clock (gettimeofday(), std::chrono on the desktop). Not on AVR and Uno R4
TinyCTSClient	Another BLE device: a BLE time repeater
TinyCTSSourceAdapter<T>	Any object with a getTimeMs(), e.g. the TinyNTPClient of TinyNTP
your class	Derive from TinyCTSTimeSource

Software clock

TinyCTSClockSource clock_;
clock_.setTime(rtc.now().unixtime());   // seconds since 1970 (and optionally ms)
server.begin(clock_);

Set it regularly (e.g. every few minutes); it must be read or set at least once every 49 days because of the overflow of millis().

System clock

configTime(0, 0, "pool.ntp.org");   // ESP32: set the clock with SNTP (UTC)
TinyCTSSystemSource source;
server.begin(source);

Times before 2023-11-14 are treated as "clock not set".

Your own source

class MySource : public TinyCTSTimeSource {
 public:
  uint64_t getTimeMs() override { return myClock.unixMs(); }
  bool setTimeMs(uint64_t ms) override { return myClock.set(ms); }  // optional
};

getTimeMs() is called for each request, so it must be fast and must not block. setTimeMs() is only called if you allowed the clients to set the time (see Security); the default refuses.