Problem with calling function once every x minutes

Projects Programming
1

[Setup: Arduino Uno IDE 1.8.0, Ethernet Shield 2 with PoE, time sync with router (which itself is on sync with an external time provider), included libraries Time.h and TimeLib.h]

Hi all,

I am currently trying to figure out how to have a function being called once every 5 minutes, but so far the result I have been able to achieve is a far cry from what I need.

The code I am tinkering with is as follows:

void loop()
{
 if (minute() - minute(t) >= 5)  //doesn't work: keeps running endlessly and
                                              //     not once every 5 minutes
{
 for(int i = 0; i < 1; i++)          //for should run only once when condition
			                     //within if is met
{
 syncedTime();			    // function I am currently testing with

/*Alternative testing code
 Serial.print(minute()); 	    // Returns current minute correctly
 Serial.println();
 Serial.print(minute(t)); 	    // Returns only zeroes, and hence not the
                                           // minute one expects from now();
Serial.println();
*/

}
time_t t = now();

}

}

With the call to function syncedTime() enabled, this is what I get as a result:

Waiting for sync with Fritz!Box...

Transmit NTP Request
Received NTP Response

Fritz!Box has set the system time!

[22:02:00 / 05-01-2017]

[22:02:00 / 05-01-2017]

[22:02:00 / 05-01-2017]

[22:02:00 / 05-01-2017]

[22:02:01 / 05-01-2017]

[22:02:01 / 05-01-2017]

[22:02:01 / 05-01-2017]

[22:02:01 / 05-01-2017]

Etc. Etc.

Instead of once every two minutes, as specified, I am seeing numerous timestamps per second. When the function call is commented out, and the Serial.print lines are activated, I am getting this:

Waiting for sync with Fritz!Box...

Transmit NTP Request
Received NTP Response

Fritz!Box has set the system time!

6
0
6
0
6
0
6

Etc. etc.

Where Serial.print(minute()) correctly returns the current minute, Serial.print(minute(t)) only returns zeroes. Obviously, the instruction time_t t = now(); doesn't do what I expected it to do. As I am completely stuck on this one, I would much appreciate any leads that would help me getting further.

Thanking you in advance for your time,

Simon

2

Can you share your minute() and now() functions?

3

You will have more success getting help if you attach your whole sketch.

.

4

Quite sure I don't understand everything going on there but...

5 minutes is 300,000 milliseconds

Maybe just do it blink without delay style with a interval value of 300,000?

5

claudiaa, LarryD,

For the complete sketch, please see below. Would I need to attach both Time.h and TimeLib.h as well? For your information: the function syncedTime() I am calling in the sketch is eventually to replaced by another one, but is used here for testing purposes.

Thanks for your attention,

Simon

#include <Ethernet2.h>
#include <EthernetUdp2.h>
#include <SPI.h>
#include <Time.h>
#include <TimeLib.h>

// MAC-adres Arduino
byte mac[] =
  {
  0x99, 0x99, 0x99, 0x99, 0x99, 0x99 // Dummy MAC address
  };

IPAddress timeServer(999, 999, 999, 9);   // Dummy IP-address of Fritz!Box acting as NTP-server

IPAddress ip(999, 999, 999, 99);          // Dummy IP-adres of Arduino

unsigned int localPort = 8888;            // local port to listen for UDP packets

const int timeZone = 1;     // Central European Time == Greenwich Mean Time (GMT) + 1

int t;

// A UDP instance to let us send and receive packets over UDP
EthernetUDP Udp;

void syncedTime(void);

void setup() 
{
  Serial.begin(9600);

  Ethernet.begin(mac, ip);
  
  Udp.begin(localPort);

  Serial.println("Waiting for sync with Fritz!Box...\r\n");
  
  setSyncProvider(getNtpTime);
  if(timeStatus()!= timeSet) 
  Serial.println("Unable to sync with Fritz!Box\r\n");
  else
  Serial.println("Fritz!Box has set the system time!\r\n");
}

void loop()
{
if (minute() - minute(t) >= 2) // doesn't work: keeps running endlessly and not once every 2 minutes
{
for(int i = 0; i < 1; i++) // for should run only once
{
syncedTime();
/*
Serial.print(minute()); // Returns current minute correctly
Serial.println();
Serial.print(minute(t)); // Returns 0, and hence not the minute one expects from time_t t = now();
Serial.println();
*/
}

time_t t = now();
}

//  now();
}

//-------- NTP code ----------
const int NTP_PACKET_SIZE = 48; // NTP time is in the first 48 bytes of message
byte packetBuffer[NTP_PACKET_SIZE]; //buffer to hold incoming & outgoing packets

time_t getNtpTime()
{
  while (Udp.parsePacket() > 0) ; // discard any previously received packets
  Serial.println("Transmit NTP Request");
  sendNTPpacket(timeServer);  
  uint32_t beginWait = millis();
  while (millis() - beginWait < 1500)
  {
    int size = Udp.parsePacket();
    if (size >= NTP_PACKET_SIZE)
    {
    Serial.println("Received NTP Response\r\n");

    Udp.read(packetBuffer, NTP_PACKET_SIZE); // read the packet into the buffer

//  The timestamp starts at byte 40 of the received packet and is four bytes,
//  or two words, long. First, extract the two words:

    unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
    unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
//  Combine the four bytes (two words) into a long integer, which is
//  NTP time (seconds since Jan 1 1900):
    unsigned long secsSince1900 = highWord << 16 | lowWord;
//  now convert NTP time into everyday time (Unix time starts on Jan 1 1970. In seconds, that's 2208988800)
    unsigned long CET = secsSince1900 - 2208988800UL + (timeZone*3600UL);
    return CET;
    }
  }

  Serial.println("No NTP Response :-(\r\n");
  return 0; // return 0 if unable to get the time
}

// send an NTP request to the time server at the given address
void sendNTPpacket(IPAddress &address)
{
  // set all bytes in the buffer to 0
  memset(packetBuffer, 0, NTP_PACKET_SIZE);
  // Initialize values needed to form NTP request
  // (see URL above for details on the packets)
  packetBuffer[0] = 0b11100011;   // LI, Version, Mode
  packetBuffer[1] = 0;     // Stratum, or type of clock
  packetBuffer[2] = 6;     // Polling Interval
  packetBuffer[3] = 0xEC;  // Peer Clock Precision
  // 8 bytes of zero for Root Delay & Root Dispersion
  packetBuffer[12]  = 49;
  packetBuffer[13]  = 0x4E;
  packetBuffer[14]  = 49;
  packetBuffer[15]  = 52;
  // all NTP fields have been given values, now
  // you can send a packet requesting a timestamp:                 
  Udp.beginPacket(address, 123); //NTP requests are to port 123
  Udp.write(packetBuffer, NTP_PACKET_SIZE);
  Udp.endPacket();
}

void syncedTime(void)
{

//this code works but uses up more memory
//sprintf(dateBuffer,"[%02u:%02u:%02u / %02u-%02u-%04u]\r\n\n",hour(),minute(),second(),day(),month(),year());
//Serial.print(dateBuffer);  

//alternative code uses less memory
  Serial.print('[');
  if (hour() < 10)
  {
  // In the first 9 hours of each day, we'll want a leading '0'
  Serial.print('0');
  }
  Serial.print(hour());
  Serial.print(":");
  if (minute() < 10)
  {
  // In the first 9 minutes of each hour, we'll want a leading '0'
  Serial.print('0');
  }
  Serial.print(minute());
  Serial.print(":");
  if (second() < 10)
  {
  // In the first 9 seconds of each minute, we'll want a leading '0'
  Serial.print('0');
  }
  Serial.print(second());
  Serial.print(" / ");
  if (day() < 10)
  {
  // In the first 9 days of each month, we'll want a leading '0'
  Serial.print('0');
  }
  Serial.print(day());
  Serial.print("-");
  if (month() < 10)
  {
  // In the first 9 months of each year, we'll want a leading '0'
  Serial.print('0');
  }
  Serial.print(month());
  Serial.print("-");
  Serial.print(year());  
  Serial.println("]\r\n");
}
8

@Delta_G

The thought proces was that I wanted to make sure that each time a predefined period had elapsed, a given function was called only once. My approach obviously didn't work, but I have now solved my problem by employing the solution suggested in another thread (https://forum.arduino.cc/index.php?topic=337512.0).

Anyway, thanks for helping!

if (millis () - target_time >= updateInterval)
  {
    target_time += updateInterval ;   // changes scheduled time exactly, no slippage will happen

    uploadTemps();

}