add configTzTime() to setup sntp using TZ environment variable (espressif#608)

Author: markyad

cores/esp32/Arduino.h

@@ -168,6 +168,8 @@ unsigned long pulseInLong(uint8_t pin, uint8_t state, unsigned long timeout = 10
 extern "C" bool getLocalTime(struct tm * info, uint32_t ms = 5000);
 extern "C" void configTime(long gmtOffset_sec, int daylightOffset_sec,
  const char* server1, const char* server2 = nullptr, const char* server3 = nullptr);
+extern "C" void configTzTime(const char* tz,
+ const char* server1, const char* server2 = nullptr, const char* server3 = nullptr);
 
 // WMath prototypes
 long random(long);

cores/esp32/esp32-hal-time.c

@@ -45,7 +45,6 @@ static void setTimeZone(long offset, int daylight)
  * */
 void configTime(long gmtOffset_sec, int daylightOffset_sec, const char* server1, const char* server2, const char* server3)
 {
-
  if(sntp_enabled()){
  sntp_stop();
  }
@@ -57,6 +56,24 @@ void configTime(long gmtOffset_sec, int daylightOffset_sec, const char* server1,
  setTimeZone(gmtOffset_sec, daylightOffset_sec);
 }
 
+/*
+ * configTzTime
+ * sntp setup using TZ environment variable
+ * */
+void configTzTime(const char* tz, const char* server1, const char* server2, const char* server3)
+{
+ if(sntp_enabled()){
+ sntp_stop();
+ }
+ sntp_setoperatingmode(SNTP_OPMODE_POLL);
+ sntp_setservername(0, (char*)server1);
+ sntp_setservername(1, (char*)server2);
+ sntp_setservername(2, (char*)server3);
+ sntp_init();
+ setenv("TZ", tz, 1);
+ tzset();
+}
+
 bool getLocalTime(struct tm * info, uint32_t ms)
 {
  uint32_t count = ms / 10;