Epoch time, Do most people know ?

[Charles Linquis]

But if you are trying to translate NETWORK time, that is the time from Jan 1, 1900

The code below takes a "brute force" approach, but works. I'm sure some math whiz could
certainly come up with a better formula.



HOffset = Local offset from GMT
Sign = 1 if you are EARLIER than GMT
Sign = 2 if you are LATER than GMT ("+")
DST = 1 if you are using DST

The program takes a "shortcut" in that it calculates time since Jan 1, 2000

  
               IF sign = "1" then
                  if DST = 1 and HOffset = 0 THEN 
                       Sign = "2"
                       GOTO OtherSide
                  ENDIF     
                    
                     TimeNow = Timenow - ((HOffset - DST) * 3600)
               ENDIF
             
OtherSide:             
               IF Sign = "2" THEN
               
                  TimeNow = TimeNow + ((Hoffset + DST) * 3600)
               ENDIF   
                                     
                SINCEJAN2009 = TIMENOW - 3439756800   ; 3439756800 is the #of sec from Jan1 1900 to Jan1 2009
               
                RUNNINGSECONDS = SINCEjAN2009
                YR = 2009
                
GETYEAR:
        
                    LEAP = (YR//4)    ; = 0 if leap year
                    
                    if LEAP = 0 then
                        SecondsInYear = 31622400 ;366*60*60**24
                     
                    ELSE
                        SecondsInYear = 31536000 ;365*60*60*24
                     
                    endif
                       
                    If RunningSeconds > SecondsInYear Then
                        RunningSeconds = RunningSeconds - SecondsInyear
                        YR = YR + 1
                        GOTO GetYear
                    ENDIF
               
                 Mo = 1 ; Start with Month = 1  
                 
        
GETMONTH:        
                IF LEAP > 0 THEN
                   lookup2 MO,[0,2678400,2419200,2678400,2592000,2678400,2592000,2678400,2678400,2592000,2678400,2592000,2678400],SecondsInMonth
                ELSE
                   LOOKUP2 MO,[0,2678400,2505600,2678400,2592000,2678400,2592000,2678400,2678400,2592000,2678400,2592000,2678400],SecondsInMonth
                ENDIF
                
                If RunningSeconds >= SecondsInMonth THEN
                   RunningSeconds = RunningSeconds - SecondsInMonth
                
                MO = MO + 1
                GOTO GETMONTH
                ENDIF   
FINDDAYS:
        
                DA = RUNNINGSECONDS/86400
                RUNNINGSECONDS = RUNNINGSECONDS//86400
     
                HR = RUNNINGSECONDS/3600 
                RUNNINGSECONDS = RUNNINGSECONDS//3600
       
                MN = RUNNINGSECONDS/60
                RUNNINGSECONDS = RUNNINGSECONDS//60
                SC = RUNNINGSECONDS
            
                Da = Da + 1
               HSEROUT [13,10,13,10,DEC2 HR,":",DEC2 MN,":",DEC2 SC,"   ",DEC2 MO,"/",DEC2 DA,"/",#YR,13,10]

[HenrikOlsson]

Hi Charles,
Exactly, with SNTP "time began" at 1/1-1900.
I see your code uses LONGS which I'm trying to avoid but I'll digest it and see what might come out, thanks for sharing, I appreciate it!

/Henrik.

[Charles Linquis]

I guess that I left out some stuff in the code above.

It is designed for use with a Lantronix XPort. It logs on to port 123 of timeservers and comes back with network time.
And, yes, you ***MUST*** use 18F chips!



The stuff that goes before it is -

THEADER[0] = $2           ' STX

        THEADER[1] = TSIP1  ' DESTINATION IP
        THEADER[2] = TSIP2
        THEADER[3] = TSIP3
        THEADER[4] = TSIP4

        THEADER[5] = 0            ; DESTINATION PORT HIGHBYTE
        THEADER[6] = 123          ; DESTINATION PORT LOWBYTE
                    
        LRC1 = 0
        LRC2 = 0 
      
        For X = 1 to 6
             LRC1 = LRC1 ^ THeader[x]
        next X
                       
        THEADER[7] = LRC1               
        THEADER[8] = 0               
        THEADER[9] = 48                                             'Data Length lowbyte
    
;Send the header
       
          For X = 0 to 9
            HSEROUT2 [THeader[X]]
          Next X   
         
          LRC2 = LRC2 ^ THeader[8]
          LRC2 = LRC2 ^ THeader[9]
        
;Send the data
          HSEROUT2 [$1B]
           LRC2 = LRC2 ^ $1B
          For X = 0 To 46
            HSEROUT2 [0]
            LRC2 = LRC2 ^ 0
          NEXT X     
                  
;Send the Checksum (LRC)            
         
          HSEROUT2 [LRC2]
getresponse:         
          
    
         HSERIN2 1000,NoResponse,[Wait($2)]                                                      
         hserin2 200,NoResponse,[SKIP 41,TimeNow.Byte3,TimeNow.Byte2,TimeNow.Byte1,TimeNow.Byte0]

[HenrikOlsson]

Thanks Charles,
I'm using the 18LF46K22 and W5100 ethernet chip, the SNTP stuff are done and I get the seconds count from the server, no issues there. It's the conversion from seconds to true time that's bugging me and the reason I'm trying to avoid longs is that it adds a lot of overhead to the program even in sections not actually using longs.

I'm on my way to convert your convert-routine to use 16 bit variables but it does get a bit messy...

Thanks again for sharing!
/Henrik.

[Charles Linquis]

It shouldn't be too bad - breaking it into 16 bit 'chunks' , you will just have an offset that is not just hours, but hours, minutes and seconds.