Creating a timestamp (RTClib)

[cyberdrive]

Hiya Community!

Atm i am working on my pool control unit and i do want to integrate a temp (DS1820) logging function (writing to flash in a ring buffer later).

I do have the RTC unit with a DS1307 and i am useing RTClib.
What i want to do is creating something like:

DD/MM hh:mm 26.4         ( where 26.4 is in °C)

what i do have so far is:

Code: [Select]


...
char TempBuf[10] = "         ";
char buffer[17];

dtostrf(PoolTemp, 4, 1, TempBuf);

sprintf(buffer,"%02i/%02i", now.day(), now.month());
Serial.println(buffer);


if i do continue it like:

Code: [Select]


...
char TempBuf[10] = "         ";
char buffer[17];

dtostrf(PoolTemp, 4, 1, TempBuf);

sprintf(buffer,"%02i/%02i %02i:%02i %04c", now.day(), now.month(), now.hour(), now.minute(), TempBuf);
Serial.println(buffer);

it freezes my arduino. Of course it has something to do with the parameters in sprintf but i don´t get it.

Your help is very much appreciated!
Cyber

[michael_x]

char buffer[7];
seems a bit small

[cyberdrive]

sorry, of course it meant to be 17...

i do have edited the post above THX!

[Coding Badly]

buffer is too small.  It has to be big enough to accommodate all the characters you write to it in the sprintf call.  Which means we count...

%02i   - two characters
/   - one character
%02i    - three (there is a trailing space there)
%02i   - two
:   - one
%02i    - three (another space)
%04c   - four

...16 (assuming I counted correctly).  One extra for the "null terminator".  Change the definition of buffer to this...

Code: [Select]

char buffer[17];

[michael_x]

char Tempbuf[] has to be referred to as "%4s" in sprintf, I assume

[cyberdrive]

Huge THANKS for all the help till now! Just great in here!

Version 1 (only day & month) is working. Even when only adding the statement for "hour" - i get freezed

[michael_x]

you need to provide (at least) as many parameters after the format, as "%" in the format string ...
( or you reverted to  char buffer[7]; )

or some other simple mistake

%i or %d or %u should all be fine and equivalent for an unsigned decimal integer

Hm... try a test sketch with only

Code: [Select]

static char buffer[20];
sprintf(buffer, "%02u/%02u %02u:%02u", 6, 1, 23, 59);
Serial.println(buffer);

[cyberdrive]

Thanks for the hint, but it freezes with that code too...  

i do think it´s the code itself - anywhere else... i do change a bit of code anywhere and it gets freezed. At nearly 1000 lines of code, do you have any tip where to search first?

Cyber

[cyberdrive]

I do have tracked it down to my logging function. If i do comment that function call out everything is working fine.

myBuffer1 or myBuffer2 is working, but not both at the same time - do you see a mistake?

complete code at: http://pastebin.com/Ju8feXYG

Code: [Select]


void LoggingValues()   // check if values have to be written to history
{
 DateTime now = RTC.now();
 
 int LastTimeSavedVal= 0;    // now.hour() of last time logging
 int PoolTempSavePosVal = 0;    // containing save position of ring logging buffer (value 0 to 8 = 9 values for logging - then reset)
 int iTempVal;
 unsigned int MinAddr = 0;    // calc memory position for writing actual Timestamp
   
 LastTimeSavedVal = EEPROM.read(LastTimeSaved);
 PoolTempSavePosVal = EEPROM.read(PoolTempSavePos);

 MinAddr = EEPROM_MIN_ADDR + PoolTempSavePosVal*BytesPerTempVal;

 for (iTempVal = 0; iTempVal < ValuesToLog; iTempVal++)
 {
   if (now.hour() >= (WakeUpTime + iTempVal*ValueLoggingIntervall) && LastTimeSavedVal < (WakeUpTime + iTempVal*ValueLoggingIntervall))    //calc if value has to be stored
   {
     getMedianTemps();    // reading temps from DS1820
 
     dtostrf(PoolTemp, 4, 1, TempBuf);    // convert float temperature for character operations
     
     PoolTempSavePosVal++;    
     if (PoolTempSavePosVal > 8)   // ring buffer reset
     {
       PoolTempSavePosVal = 0;
       //Serial.println("PoolTempSavePos Reset");
     }      
 
char myBuffer1[11];
sprintf(myBuffer1,"%02i/%02i %4s", now.day(), now.month(), TempBuf);
//Serial.println(myBuffer1);

char myBuffer2[7];
sprintf(myBuffer2," %02i:%02i", now.hour(), now.minute());
//Serial.println(myBuffer2);

    StringTemp = String(myBuffer1) + String(myBuffer2);
    StringTemp.toCharArray(TempChar, 18);    
     Serial.print("DEBUG WERT: ");      
     Serial.println(TempChar);
...


[michael_x]

Code: [Select]

     StringTemp = String(myBuffer1) + String(myBuffer2);
     StringTemp.toCharArray(TempChar, 18);   

Strings are bad, and + is a very expensive operator on Strings.
And I don't see the definition of TempChar...

What about just throwing that part away? 
If you use it just for the Serial.println, either use the commented println's above instead, or setup your debug message in one sprintf() into a char array of sufficient size directly...

[cyberdrive]

I am open of throwing it away 
What i do want to get is a string / char array like:
06/01 12:00 26.4
which i could write to flash. (for example 3 times a day).

That + operation was trying a workaround because of the freezing when putting together all in one char array / a string. I will put it together char by char in one char array as u mentioned.

TempChar is globaly defined:

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char TempChar[17] = "1234567890abcdef";