B4R Library rESP8266rtc .. a Real Time Clock

** Now also supports ESP-32 modules **

I created this library as a software based Real Time Clock.
You don't need any additional hardware modules.
It does NOT run any special background code to keep the RTC alive.
It can generate Alarm Events at required Date/Times.
It can be calibrated from your own web based internet UTC time source using it's built in GetUTC function. (see post #7)
It also contains several functions to simplify the manipulation of date/times as seconds.
It gets it's timing by calibrating the millis() function available from Arduino.
Generated Alarm Events are managed by the B4R Scheduler class.

Code: Copy 
#Region Project Attributes
    #AutoFlushLogs: True
    #CheckArrayBounds: True
    #StackBufferSize: 300
#End Region
 
Sub Process_Globals
   Public Serial1 As Serial
   Private wifi As ESP8266WiFi
   Private DT(8) As Byte
   Private rtc As ESP8266rtc
End Sub
 
Private Sub AppStart
   Serial1.Initialize(115200)
   Log("AppStart")
 
   If wifi.Connect2("your ssid","your password") Then   'change to your network SSID (use Connect2 if a password is required).
       Log("Connected to wireless network.")
 
       rtc.Initialize("rtc_Alarm",True)
 
       'I have provided my own "url.php" as an example only.
       'you must create your own as per the details in the post for v1-04
       err = rtc.GetUTC(DT,"www.starchild.com.au","/utc.php"))
 
       If err <> 0 Then
               Log("GetUTC failed: ",err)
       End If
 
       rtc.SetClock(DT,8,0)   'offset for Western Australia. UTC +08:00
       Log(rtc.ReadClock(DT))
       Log("RTC: ",DT(0),",",DT(1),",",DT(2),",",DT(3),",",DT(4),",",DT(5),",",DT(6),",",DT(7))
 
        rtc.SetAlarm(1,rtc.Sec2DT(rtc.DT2Sec(DT)+10))
        rtc.SetAlarm(2,rtc.Sec2DT(rtc.DT2Sec(DT)+5))
        rtc.SetAlarm(3,rtc.Sec2DT(rtc.DT2Sec(DT)+15))
        rtc.SetAlarm(9,rtc.Sec2DT(rtc.DT2Sec(DT+rtc.SECONDS_1MINUTE))
        rtc.SetAlarm(5,rtc.ThisTime(6,30,0))   'set alarm for 6:30am (within the next 24hrs)
     Else
       Log("Failed to connect.")
    End If
 
End Sub
 
private Sub rtc_Alarm(index As Byte)
    If index=0 Then
        'tick every second
        rtc.ReadClock(DT)
        Log("RTC: ",rtc.ShortDOW(DT),", ",rtc.ShortDate(DT),", ",rtc.Time24(DT))
        Return
    End If
    Log("AlarmEvent:  ",index)
End Sub


Notes: My testing over several days showed a loss of 1 to 2 sec per day. The RTC could be set (SetClock) every week or so from the GetUTC() function if it is required to maintain accuracy. As the Arduino Millis() function can only count continuously for about 40days the RTC should be set at least once a month.

Now updated to v1.05
See post below for details.
 

Attachments

Last edited:
Click to expand...
I have updated the rESP8266rtc library to version 1.01
It can be downloaded from the top post.

New Functions:
ShortDate .. returns a string formatted with a simple date.
Time12 .. returns a string formatted with a 12 hour time (with am/pm suffix)
Time24 .. returns a string formatted with a 24 hour time (includes seconds)
SECONDS_1WEEK .. constant for 1 week as seconds value
date/time array now returns day-of-week field in formerly reserved byte for functions ReadClock and Sec2DT.

Bug fix:
resolved issue in converting between seconds and date/time array.

--------------
 
Last edited:
New update for rESP8266rtc library, now v1.03
The download in the top post has been updated.
Changes:
Initialize .. now has an additional parameter (TickEverySecond as Boolean)
New Function:
GetDT .. to get date/time from your own server. See B4J "DTserver.zip" example here.
 

Attachments

New update for rESP8266rtc library, now v1.04
The download in the top post has been updated.

As reported by "janderkan" the time server TimeAPI.org is dead.

The library function "GetUTC()" has been rewritten to allow your own time source to be accessed over the internet.

New function:
... rtc.GetUTC(DT() as byte, Host as string, Url as string)

The example code in the top post has been updated to use this new function with my own "utc.php" URL file.
You can use my site to do testing but you must set up your own time source on your own web site.

Note: I will be deleting my utc.php URL from my web site in the near future, so don't rely on it.

I have attached the zip "time source url.zip" containing the PHP script file "utc.php" for you to place on your own web site.
 

Attachments

Last edited:
I'm using this handy library in my project and love the ability to set alarms.

From what I can tell, there isn't a built-in method for setting an alarm simply as a time. For example, to set an alarm for the next occurrence of 00:30. So if it is currently before 00:30, the alarm would be set to today's date @ 00:30. If it is after 00:30, then it would be set to tomorrow's date @ 00:30.

I'm trying to work out a little sub where I can pass a time to it (00:30) and have it return a DT object that would represent the next occurrence of this time. With this object, I would then set an alarm with using something like rtc.SetAlarm(1,MyDT)

I have ideas on how I could do it, but I feel like there is probably a much easier way than what I am thinking. I am trying to follow some examples based on general Google searches but the examples use methods not available to me in B4R.
 
Update: This is what I came up with in case anyone is interested. I have tested when the requested time has not yet occurred but have not had a chance to test when the requested time has passed. I think the math is right. I'm heading out the door but will test more thoroughly when I have a chance.

Edit: I left it running overnight and confirmed this morning that the alarm event triggered where I had it set (on the next day), so this code does work. There may be a more efficient way, but it does work.

Code: Copy 
Private Sub MyDT (HHMM As String) As Byte(8) ' Example:  "02:00", 24 hour format
    Dim Result(8) As Byte
    Dim bc As ByteConverter
    Dim HH, MM, RequestedTimeInSeconds As Long
    Dim cHH, cMM, cSS, CurrentTimeInSeconds As Long
 
    Dim n As Byte = 0
    For Each s() As Byte In bc.Split(HHMM, ":")
        Select n
            Case 0
                HH = bc.StringFromBytes(s)
            Case 1
                MM = bc.StringFromBytes(s)
        End Select
        n = n + 1
    Next
    RequestedTimeInSeconds = (HH * 3600) + (MM * 60)
 
    rtc.ReadClock(DT)
    Dim CT As String = rtc.Time24(DT)
    Dim n As Byte = 0
    For Each s() As Byte In bc.Split(CT, ":")
        Select n
            Case 0
                cHH = bc.StringFromBytes(s)
            Case 1
                cMM = bc.StringFromBytes(s)
            Case 2
                cSS = bc.StringFromBytes(s)
        End Select
        n = n + 1
    Next
 
    CurrentTimeInSeconds = (cHH * 3600) + (cMM * 60) + cSS
 
    If RequestedTimeInSeconds > CurrentTimeInSeconds Then 'Return a DT object for today at requested time
        Result = DT
        Result(4) = HH 'Hour
        Result(5) = MM 'Min
        Result(6) = 0  'Sec
        Return Result
    Else 'Return a DT object for tomorrow at requested time
        Dim Offset As Long = 86400 - (CurrentTimeInSeconds - RequestedTimeInSeconds)
        Result = rtc.Sec2DT (rtc.DT2Sec(DT) + Offset)
        Return Result
    End If
 
    ' Example:  rtc.SetAlarm(1, MyDT ("00:30"))

End Sub
 
Last edited:
Kevin said:
I'm using this handy library in my project and love the ability to set alarms.

From what I can tell, there isn't a built-in method for setting an alarm simply as a time. For example, to set an alarm for the next occurrence of 00:30. So if it is currently before 00:30, the alarm would be set to today's date @ 00:30. If it is after 00:30, then it would be set to tomorrow's date @ 00:30.

I'm trying to work out a little sub where I can pass a time to it (00:30) and have it return a DT object that would represent the next occurrence of this time. With this object, I would then set an alarm with using something like rtc.SetAlarm(1,MyDT)

I have ideas on how I could do it, but I feel like there is probably a much easier way than what I am thinking. I am trying to follow some examples based on general Google searches but the examples use methods not available to me in B4R.
Click to expand...

Sorry for my delay in my reply.
Good to see you have come up with a solution.

For me, I would want to handle date/time values as an 8 byte array, as in the example. (strings are difficult to manipulate, and memory inefficient with B4R coding)
In this case the time bytes for hour/minute/second (of the alarm) can be numerically tested to determine if the required alarm time is before the current time (a couple of IF statements) and if so, then adding seconds for 1 day to the alarm date/time value (as seconds). Then use this new date/time value to set the alarm event.

Hope this helps.
 
I appreciate the feedback. I'm trying to wrap my head around working with bytes. At some point I may revisit this code in order to do it more efficiently. I'm getting very close to finally being finished with the programming aspect and hope to put it to actual use soon.

I appreciate the time library. It is very useful in my project. :)
 
New update for rESP8266rtc library, now v1.05
The download in the top post has been updated.

This library can now also be used for the ESP-32 modules.

Thanks to Kevin's request above, I have added the following function.

... rtc.ThisTime(Hour,Minute,Seconds) .. returns date/time within the next 24 hours.

example:
rtc.SetAlarm(5,rtc.ThisTime(6,30,0))
'if current time is 10am, then it sets alarm for 6:30am tomorrow, but
'if current time is 5am, then it sets alarm for 6:30am later this morning.
 
Last edited:
I used Time12 function to get time in am/pm format, but the am/pm string is not spaced from time-part, it looks like this
03:24pm not 03:24 pm, is it possible to add space between them?

TIA
 
Mostez said:
I used Time12 function to get time in am/pm format, but the am/pm string is not spaced from time-part, it looks like this
03:24pm not 03:24 pm, is it possible to add space between them?

TIA
Click to expand...
Use this function to replace "pm" with " pm"

Strings and Bytes

B4R strings are different than in other B4X tools. The reasons for these differences are: 1. Very limited memory. 2. Lack of Unicode encoders. A String object in B4R is the same as C char* string. It is an array of bytes with an additional zero byte at the end. The requirement of the last zero...
www.b4x.com www.b4x.com
 
Mostez said:
I used Time12 function to get time in am/pm format, but the am/pm string is not spaced from time-part, it looks like this
03:24pm not 03:24 pm, is it possible to add space between them?

TIA
Click to expand...


I personally like the am/pm abutting the time digits.
But you can change the library for your own preference.

The library code is written as text inside the file "rESP8266rtc.cpp"
Edit this file with a text editor (like Notepad++) not windows notepad.
at line 420 (just after the minutes output and before the output of "a" or "p") insert this additional line;
pm.print((byte)' '); //single space chr

Next time you compile your B4R project it will now include a SPACE before the "am" or "pm" following the 12hr time.

Note:
B4R libraries are written in C, so they are easy to change around when you need something a bit different.
 
You must log in or register to reply here.

Similar Threads

D
  • Question Question
B4R Question rESP8266rtc erroneous alarms
Replies
2
Views
2K
daveinhull
D
Starchild
  • Article Article
Other ESP32 - use real time clock library rESP8266rtc
Replies
0
Views
3K
Starchild
Starchild
Starchild
  • Article Article
B4R Library Software Real Time Clock
Replies
19
Views
12K
Starchild
Starchild
rwblinn
  • Article Article
B4R Tutorial RTC DS1302 Example
2
Replies
22
Views
29K
rwblinn
rwblinn
A
Wish Real Time Clock RTC_DS1307
Replies
7
Views
7K
inakigarm
I
Back
Top