How to use NTP with the Aduino Leonardo

Placed on 2020-10-25
Arduino Leonardo - NTP Request

#include <Wire.h>

// You can find the TimeLib and the ds3231 library on my github page https://github.com/Sani7/NTP-config_reader-DS3231

#include <ds3231.h>

struct ts t;


  
#include <TimeLib.h>	

#define ssid "SSID"     // Put you're WiFi SSID here
#define pswd "PSWD"     // Put you're WiFi PSWD here

// NTP stuff
// Get Time from NTP server (Network Time Protocol, RFC 5905)
// NTP uses UDP/IP packets for data transfer because of the fast
// connection setup and response times.

// The official port number for the NTP (that ntpd and ntpdate listen and talk to) is 123.
// The unit of time is in seconds, and the epoch is 1 January 1900.
// its gives you UTC time, which is the time at Greenwich Meridian (GMT)
// The NTP timestamp is a 64 bit binary value, built from an unsigned 32-bit seconds value
// and a 32-bit fractional part. In this notation the value 3.5 would be represented by the 64-bit string:
// 0000|0000|0000|0000|0000|0000|0000|0011 . 1000|0000|0000|0000|0000|0000|0000|0000
// If you take all the bits as a 64 bit unsigned integer,
// store it in a floating point variable with at least 64 bits of mantissa (usually double)
// and do a floating point divide by 2^32, you'll get the right answer.
// On a standard arduino unfortunately we don't have 64 bits doubles.
// but most RTC have just second level info, so no need to get the second half (or first byte possibly)

// Only the first four bytes of an outgoing NTP packet need to be set for what we want to achieve
// appropriately, the rest can be whatever.
//The header fields of the NTP message are as follows:
//
//LI  Leap Indicator (2 bits)
//This field indicates whether the last minute of the current day is to have a leap second applied. The field values follow:
//0: No leap second adjustment
//1: Last minute of the day has 61 seconds
//2: Last minute of the day has 59 seconds
//3: Clock is unsynchronized
//
//VN  NTP Version Number (3 bits) (current version is 4).
//
//Mode  NTP packet mode (3 bits)
//The values of the Mode field follow:
//0: Reserved
//1: Symmetric active
//2: Symmetric passive
//3: Client
//4: Server
//5: Broadcast
//6: NTP control message
//7: Reserved for private use
//
//Stratum level of the time source (8 bits)
//The values of the Stratum field follow:
//0: Unspecified or invalid
//1: Primary server
//2–15: Secondary server
//16: Unsynchronized
//17–255: Reserved
//
//Poll  Poll interval (8-bit signed integer)
//The log2 value of the maximum interval between successive NTP messages, in seconds.
//
//Precision Clock precision (8-bit signed integer)
//The precision of the system clock, in log2 seconds.

static const unsigned long ntpFirstFourBytes = 0xEC0600E3; // NTP request header, first 32 bits
const uint8_t NTP_PACKET_SIZE = 48; // NTP time stamp is in the first 48 bytes of the message


// after a successful querry we will get a 48 byte answer from the NTP server.
// To understand the structure of an NTP querry and answer
// see http://www.cisco.com/c/en/us/about/press/internet-protocol-journal/back-issues/table-contents-58/154-ntp.html
// so if we want to read the "Transmit Timestamp" then we need to
// Read the integer part which are bytes 40,41,42,43
// if we want to round to the nearest second if we want some accuracy
// Then fractionary part are byte 44,45,46,47
// if it is greater than 500ms byte 44 will be > 128
// and thus by only checking byte 44 of the answer we can round to the next second;
// 90% of the NTP servers have network delays below 100ms
// We can also account for an assumed averaged network delay of 50ms, and thus instead of
// comparing with 128 you can compare with (0.5s - 0.05s) * 256 = 115;

#define SECONDROUNDINGTHRESHOLD 115

// the epoch for NTP starts in year 1900 while the epoch in UNIX starts in 1970
// Unix time starts on Jan 1 1970. 7O years difference in seconds, that's 2208988800 seconds
#define SEVENTYYEARS 2208988800UL

// to transform a number of seconds into a current time you need to do some maths
#define NUMBEROFSECONDSPERDAY 86400UL
#define NUMBEROFSECONDSPERHOUR 3600UL
#define NUMBEROFSECONDSPERMINUTE 60UL

// you might not leave in UTC time zone, set up your delta time in hours
#define UTC_DELTA_HOURS 2
/*Set offset time to adjust for your timezone, for example:
  * GMT +1
  * GMT +2
  * GMT +8
  * GMT -1
  * GMT 0 
 */
#define UTC_DELTA_MINUTES 0
const long UTC_DELTA = ((UTC_DELTA_HOURS * NUMBEROFSECONDSPERHOUR) + (UTC_DELTA_MINUTES*NUMBEROFSECONDSPERMINUTE));

// MANAGE the ESP8266. Using an ESP - 01
// we control the reset pin through the arduino
#define hardRestPIN 22
#define SHORT_PAUSE 1000UL
#define LONG_PAUSE  5000UL
const char * OK_STR = "OK\r\n";


#define ESPSERIALBAUD 115200 // Set to whatever is the default for your ESP. 

/* 
 *  =====================================================================================
 *  --------------------------------------
 *   emptyESP_RX waits for duration ms
 *   and get rid of anything arriving
 *   on the ESP Serial port during that delay
 *   --------------------------------------
 */
 
void emptyESP_RX(unsigned long duration)
{
  unsigned long currentTime;
  currentTime = millis();
  while (millis() - currentTime <= duration) {
    if (Serial1.available() > 0) Serial1.read();
  }
}

/* 
 *  --------------------------------------
 *  waitForString wait max for duration ms
 *  while checking if endMarker string is received
 *  on the ESP Serial port
 *  returns a boolean stating if the marker
 *  was found
 *  --------------------------------------
 */

boolean waitForString(const char * endMarker, unsigned long duration)
{
  int localBufferSize = strlen(endMarker); // we won't need an \0 at the end
  char localBuffer[localBufferSize];
  int index = 0;
  boolean endMarkerFound = false;
  unsigned long currentTime;

  memset(localBuffer, '\0', localBufferSize); // clear buffer

  currentTime = millis();
  while (millis() - currentTime <= duration) {
    if (Serial1.available() > 0) {
      if (index == localBufferSize) index = 0;
      localBuffer[index] = (uint8_t) Serial1.read();
      endMarkerFound = true;
      for (int i = 0; i < localBufferSize; i++) {
        if (localBuffer[(index + 1 + i) % localBufferSize] != endMarker[i]) {
          endMarkerFound = false;
          break;
        }
      }
      index++;
    }
    if (endMarkerFound) break;
  }
  return endMarkerFound;
}


/* --------------------------------------
 * espATCommand executes an AT commmand
 * checks if endMarker string is received
 * on the ESP Serial port for max duration ms
 * returns a boolean stating if the marker
 * was found
 *  --------------------------------------
 */

boolean espATCommand(const char * command, const char * endMarker, unsigned long duration)
{
  Serial1.println(command);
  return waitForString(endMarker, duration);
}


/* --------------------------------------
 * epochUnixNTP returns the UNIX time
 * number of seconds sice Jan 1 1970
 * adjusted for timezoneDeltaFromUTC
 * --------------------------------------
 */

unsigned long epochUnixNTP()
{
  unsigned long secsSince1900 = 0UL;
  unsigned long epochUnix;

  // AT+CIPSTART="UDP","be.pool.ntp.org",123
  espATCommand("AT+CIPSTART=\"UDP\",\"be.pool.ntp.org\",123", OK_STR, LONG_PAUSE);
  espATCommand("AT+CIPSEND=48", OK_STR, SHORT_PAUSE); //send 48 (NTP_PACKET_SIZE) bytes
  emptyESP_RX(1000UL); // empty the buffer (we get a > character)
  Serial1.write((char*) &ntpFirstFourBytes, NTP_PACKET_SIZE); // the first 4 bytes matters, then we don't care, whatever is in the memory will do

  // skip  AT command answer ("Recv 48 bytes\r\n\r\nSEND OK\r\n\r\n+IPD,48:")
  waitForString(":", SHORT_PAUSE);

  // read the NTP packet, extract the TRANSMIT TIMESTAMP in Seconds from bytes 40,41,42,43
  for (int i = 0; i < NTP_PACKET_SIZE; i++) {
    while (!Serial1.available());
    int c = Serial1.read();
    if ((i >= 40) && (i < 44))  secsSince1900 = (secsSince1900 << 8) + (unsigned long) ((uint8_t) (c & (int) 0x00FF)); // Read the integer part of sending time
    else if (i == 44) secsSince1900 += (((uint8_t) c) > SECONDROUNDINGTHRESHOLD ? 1 : 0);
  }

  // subtract seventy years:
  epochUnix = secsSince1900 - SEVENTYYEARS;


  espATCommand("AT+CIPCLOSE", OK_STR, SHORT_PAUSE); // close connection
  return epochUnix + UTC_DELTA;
}

// =====================================================================================

void setup()
{
  Serial.begin(115200); while (!Serial);
  Serial1.begin(ESPSERIALBAUD); while (!Serial1);

  //reset the device (pull the RST pin to ground)
  digitalWrite(hardRestPIN, LOW);
  delay(100);
  digitalWrite(hardRestPIN, HIGH);

  // connect to my WiFi network
  espATCommand("AT+RESTORE", "ready", LONG_PAUSE); // reset
  emptyESP_RX(SHORT_PAUSE);
  espATCommand("AT", OK_STR, SHORT_PAUSE); //is all OK?
  espATCommand("AT+CWMODE=1", OK_STR, SHORT_PAUSE); //Set the wireless mode
  espATCommand("AT+CWQAP", OK_STR, SHORT_PAUSE);   //disconnect  - it shouldn't be but just to make sure
  espATCommand("AT+CWJAP=\""ssid"\",\""pswd"\"", "OK", LONG_PAUSE); // connect to wifi
  espATCommand("AT+CIPMUX=0", OK_STR, SHORT_PAUSE); //set the single connection mode
  
  Wire.begin();
  // Initialize the control register of the DS3231 module
  DS3231_init(0x00);
  // Get epochTime and convert it to hours, minutes, seconds, day, month, year
  unsigned long epochTime = epochUnixNTP();
  t.hour=hour(epochTime); 
  t.min=minute(epochTime);
  t.sec=second(epochTime);
  t.mday=day(epochTime);
  t.mon=month(epochTime);
  t.year=year(epochTime);
  // Write date and time to the DS3231 module
  DS3231_set(t);
}


void loop()
{
  // Get date and time from the DS3231 module and print it in the serial monitor
  DS3231_get(&t);
  char currentTime[8];
  sprintf(currentTime, "%d:%d:%d", t.hour, t.min, t.sec);
  Serial.print("Current time: ");
  Serial.println(currentTime);
  char currentDate[9];
  sprintf(currentDate, "%d/%d/%d", t.mday, t.mon, t.year);
  Serial.print("Current date: ");
  Serial.println(currentDate);
  delay(1000);
}
Previous page 6. The ESP8266 Current Page 7. Full program 1. Introduction 2. The Schematic 3. How does NTP work? 4. DS3231 module 5. The LCD 6. The ESP8266 7. Full program Posted by Sander Speetjens
How to use NTP with the Aduino Leonardo

Arduino Leonardo - NTP Request

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