NTP Examples: revert obsolete comment and updated Time example (espressif#6073)

* Revert "Examples update, add a note for configTime() that only one ntp server is supported by lwip", fixed in espressif/esp32-arduino-lib-builder#51 This reverts commit 6b10209. * SimpleTime: add NTPoDHCP option and TimeZone env variable

Author: vortigont

cores/esp32/esp32-hal-time.c

@@ -44,8 +44,6 @@ static void setTimeZone(long offset, int daylight)
 /*
  * configTime
  * Source: https://github.com/esp8266/Arduino/blob/master/cores/esp8266/time.c
- * Note: Bundled Arduino lwip supports only ONE ntp server, 2nd and 3rd options are silently ignored
- * see CONFIG_LWIP_DHCP_MAX_NTP_SERVERS define in ./tools/sdk/esp32/sdkconfig
  * */
 void configTime(long gmtOffset_sec, int daylightOffset_sec, const char* server1, const char* server2, const char* server3)
 {
@@ -65,8 +63,6 @@ void configTime(long gmtOffset_sec, int daylightOffset_sec, const char* server1,
 /*
  * configTzTime
  * sntp setup using TZ environment variable
- * Note: Bundled Arduino lwip supports only ONE ntp server, 2nd and 3rd options are silently ignored
- * see CONFIG_LWIP_DHCP_MAX_NTP_SERVERS define in ./tools/sdk/esp32/sdkconfig
  * */
 void configTzTime(const char* tz, const char* server1, const char* server2, const char* server3)
 {

libraries/ESP32/examples/Time/SimpleTime/SimpleTime.ino

@@ -1,27 +1,65 @@
 #include <WiFi.h>
 #include "time.h"
+#include "sntp.h"
 
 const char* ssid = "YOUR_SSID";
 const char* password = "YOUR_PASS";
 
-const char* ntpServer = "pool.ntp.org";
+const char* ntpServer1 = "pool.ntp.org";
+const char* ntpServer2 = "time.nist.gov";
 const long gmtOffset_sec = 3600;
 const int daylightOffset_sec = 3600;
 
+const char* time_zone = "CET-1CEST,M3.5.0,M10.5.0/3"; // TimeZone rule for Europe/Rome including daylight adjustment rules (optional)
+
 void printLocalTime()
 {
  struct tm timeinfo;
  if(!getLocalTime(&timeinfo)){
- Serial.println("Failed to obtain time");
+ Serial.println("No time available (yet)");
  return;
  }
  Serial.println(&timeinfo, "%A, %B %d %Y %H:%M:%S");
 }
 
+// Callback function (get's called when time adjusts via NTP)
+void timeavailable(struct timeval *t)
+{
+ Serial.println("Got time adjustment from NTP!");
+ printLocalTime();
+}
+
 void setup()
 {
  Serial.begin(115200);
- 
+
+ // set notification call-back function
+ sntp_set_time_sync_notification_cb( timeavailable );
+
+ /**
+ * NTP server address could be aquired via DHCP,
+ *
+ * NOTE: This call should be made BEFORE esp32 aquires IP address via DHCP,
+ * otherwise SNTP option 42 would be rejected by default.
+ * NOTE: configTime() function call if made AFTER DHCP-client run
+ * will OVERRIDE aquired NTP server address
+ */
+ sntp_servermode_dhcp(1); // (optional)
+
+ /**
+ * This will set configured ntp servers and constant TimeZone/daylightOffset
+ * should be OK if your time zone does not need to adjust daylightOffset twice a year,
+ * in such a case time adjustment won't be handled automagicaly.
+ */
+ configTime(gmtOffset_sec, daylightOffset_sec, ntpServer1, ntpServer2);
+
+ /**
+ * A more convenient approach to handle TimeZones with daylightOffset 
+ * would be to specify a environmnet variable with TimeZone definition including daylight adjustmnet rules.
+ * A list of rules for your zone could be obtained from https://github.com/esp8266/Arduino/blob/master/cores/esp8266/TZ.h
+ */
+ //configTzTime(time_zone, ntpServer1, ntpServer2);
+
  //connect to WiFi
  Serial.printf("Connecting to %s ", ssid);
  WiFi.begin(ssid, password);
@@ -30,18 +68,11 @@ void setup()
  Serial.print(".");
  }
  Serial.println(" CONNECTED");
- 
- //init and get the time
- configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
- printLocalTime();
 
- //disconnect WiFi as it's no longer needed
- WiFi.disconnect(true);
- WiFi.mode(WIFI_OFF);
 }
 
 void loop()
 {
- delay(1000);
- printLocalTime();
+ delay(5000);
+ printLocalTime(); // it will take some time to sync time :)
 }

libraries/FFat/examples/FFat_time/FFat_time.ino

@@ -148,10 +148,6 @@ void setup(){
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  Serial.println("Contacting Time Server");
- /*
- Note: Bundled Arduino lwip supports only ONE ntp server, 2nd and 3rd options are silently ignored
- see CONFIG_LWIP_DHCP_MAX_NTP_SERVERS define in ./tools/sdk/esp32/sdkconfig
- */
 configTime(3600*timezone, daysavetime*3600, "time.nist.gov", "0.pool.ntp.org", "1.pool.ntp.org");
 struct tm tmstruct ;
  delay(2000);

libraries/HTTPUpdate/examples/httpUpdateSecure/httpUpdateSecure.ino

@@ -17,10 +17,6 @@ WiFiMulti WiFiMulti;
 
 // Set time via NTP, as required for x.509 validation
 void setClock() {
- /*
- Note: Bundled Arduino lwip supports only ONE ntp server, 2nd and 3rd options are silently ignored
- see CONFIG_LWIP_DHCP_MAX_NTP_SERVERS define in ./tools/sdk/esp32/sdkconfig
- */
  configTime(0, 0, "pool.ntp.org", "time.nist.gov"); // UTC
 
  Serial.print(F("Waiting for NTP time sync: "));

libraries/LittleFS/examples/LITTLEFS_time/LITTLEFS_time.ino

@@ -160,10 +160,6 @@ void setup(){
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  Serial.println("Contacting Time Server");
- /*
- Note: Bundled Arduino lwip supports only ONE ntp server, 2nd and 3rd options are silently ignored
- see CONFIG_LWIP_DHCP_MAX_NTP_SERVERS define in ./tools/sdk/esp32/sdkconfig
- */
 configTime(3600*timezone, daysavetime*3600, "time.nist.gov", "0.pool.ntp.org", "1.pool.ntp.org");
 struct tm tmstruct ;
  delay(2000);

libraries/SD/examples/SD_time/SD_time.ino

@@ -164,10 +164,6 @@ void setup(){
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  Serial.println("Contacting Time Server");
- /*
- Note: Bundled Arduino lwip supports only ONE ntp server, 2nd and 3rd options are silently ignored
- see CONFIG_LWIP_DHCP_MAX_NTP_SERVERS define in ./tools/sdk/esp32/sdkconfig
- */
 configTime(3600*timezone, daysavetime*3600, "time.nist.gov", "0.pool.ntp.org", "1.pool.ntp.org");
 struct tm tmstruct ;
  delay(2000);

libraries/SD_MMC/examples/SDMMC_time/SDMMC_time.ino

@@ -164,10 +164,6 @@ void setup(){
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  Serial.println("Contacting Time Server");
- /*
- Note: Bundled Arduino lwip supports only ONE ntp server, 2nd and 3rd options are silently ignored
- see CONFIG_LWIP_DHCP_MAX_NTP_SERVERS define in ./tools/sdk/esp32/sdkconfig
- */
 configTime(3600*timezone, daysavetime*3600, "time.nist.gov", "0.pool.ntp.org", "1.pool.ntp.org");
 struct tm tmstruct ;
  delay(2000);

libraries/SPIFFS/examples/SPIFFS_time/SPIFFS_time.ino

@@ -148,10 +148,6 @@ void setup(){
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  Serial.println("Contacting Time Server");
- /*
- Note: Bundled Arduino lwip supports only ONE ntp server, 2nd and 3rd options are silently ignored
- see CONFIG_LWIP_DHCP_MAX_NTP_SERVERS define in ./tools/sdk/esp32/sdkconfig
- */
 configTime(3600*timezone, daysavetime*3600, "time.nist.gov", "0.pool.ntp.org", "1.pool.ntp.org");
 struct tm tmstruct ;
  delay(2000);