+settimeofday() with NTP/TZ/DST example NTP-TZ-DST.ino

Author: d-a-v

cores/esp8266/time.c

@@ -17,6 +17,7 @@
  */
 
 #include <time.h>
+#include <sys/time.h>
 #include <sys/reent.h>
 #include "sntp.h"
 
@@ -78,6 +79,22 @@ void configTime(int timezone, int daylightOffset_sec, const char* server1, const
     sntp_init();
 }
 
+int settimeofday(const struct timeval* tv, const struct timezone* tz)
+{
+    if (tz) /*before*/
+    {
+        sntp_set_timezone(tz->tz_minuteswest / 60);
+        // apparently tz->tz_dsttime is a bitfield and should not be further used (cf man)
+        sntp_set_daylight(0);
+    }
+    if (tv) /* after*/
+    {
+        sntp_set_system_time(tv->tv_sec);
+        // ignore tv->usec
+    }
+    return 0;
+}
+
 int clock_gettime(clockid_t unused, struct timespec *tp)
 {
     (void) unused;

libraries/esp8266/examples/NTP-TZ-DST/NTP-TZ-DST.ino

@@ -0,0 +1,94 @@
+
+#include <time.h>                       // time() ctime()
+#include <sys/time.h>                   // struct timeval
+#include <ESP8266WiFi.h> 
+
+////////////////////////////////////////////////////////
+
+#define SSID            "open"
+#define SSIDPWD         ""
+#define TZ              1       // utc+TZ in hours
+#define DST_MN          60      // use 60 for summer time in some countries
+
+#define NTP0_OR_LOCAL1  1       // 0:use NTP  1:fake external RTC
+#define RTC_TEST     1510592825 // 1510592825 = Monday 13 November 2017 17:07:05 UTC
+
+////////////////////////////////////////////////////////
+
+#define TZ_MN           ((TZ)*60)
+#define TZ_SEC          ((TZ)*3600)
+#define DST_SEC         ((DST_MN)*60)
+
+void setup() {
+        Serial.begin(115200);
+        
+#if NTP0_OR_LOCAL1
+
+        // local
+        ESP.eraseConfig();
+        time_t rtc = RTC_TEST;
+        timeval tv = { rtc, 0 };
+        timezone tz = { TZ_MN + DST_MN, 0 };
+        settimeofday(&tv, &tz);
+        
+#else
+
+        // NTP
+        configTime(TZ_SEC, DST_SEC, "pool.ntp.org");
+        WiFi.mode(WIFI_STA);
+        WiFi.begin(SSID, SSIDPWD);
+        // don't wait
+
+#endif
+} 
+
+// for testing purpose:
+extern "C" int clock_gettime(clockid_t unused, struct timespec *tp);
+
+void loop() {
+
+        // same result as with time()
+        // but wrong with NTP
+        timeval tv;
+        gettimeofday(&tv, NULL);
+        Serial.print("gtod:");
+        Serial.print((uint32_t)tv.tv_sec);
+#if 0
+        // but usec is wrong
+        Serial.print("/");
+        Serial.print((uint32_t)tv.tv_usec);
+#endif
+
+        // same result as with millis()/1000
+        timespec tp;
+        clock_gettime(0, &tp);
+        Serial.print(" -- clock:");
+        Serial.print((uint32_t)tp.tv_sec);
+#if 0
+        // nsec is wrong
+        Serial.print("/");
+        Serial.print((uint32_t)tp.tv_nsec/1000000);
+        Serial.print("ms");
+#endif
+
+        // gives EPOCH+tz+dst
+        time_t now = time(nullptr);
+        Serial.print(" -- time:");
+        Serial.print((uint32_t)now);
+
+        // from boot:
+        Serial.print(" -- millis:");
+        Serial.print((uint32_t)millis());
+        Serial.print(" -- micros:");
+        Serial.print((uint32_t)micros());
+
+        // human readable
+        Serial.print(" -- ctime:(UTC+");
+        Serial.print((uint32_t)(TZ*60 + DST_MN));
+        Serial.print("mn)");
+        Serial.print(ctime(&now));
+
+        // simple drifting loop
+        delay(1000);
+}
+