DS1302 measuring elapsed time (stop watch) ?

techstudent · 2009-01-07 23:12

I got the RTC to work and display time/date onto an LCD, but what I am after is using it for measuring elapsed time, somewhere in the ranges of 45 min to 2hrs 45mins (seconds are not important) I want to set it up like a stopwatch where I can push a button to start measuring time elapsed and then push the button again to stop and display the amount of time elapsed. My problem is in figuring out how to do the math on the hrs/mins data from the DS1302 to count elapsed time? My clock is in 24hr mode, and then the next question would be how to compensate for timing 'over midnight' and doing the math from when the hours go from 24 to 1. I think what is confusing me is that the data is displayed in HEX2 format, and to go from hour HEX2 "09" to hour HEX2 "10" it is skipping HEX2 "0A" to HEX2 "0F"

I am thinking others have built stopwatch type applications, and if you could point me to any examples/discussions or just give a general idea of how to go about doing this?

Thanks

sam_sam_sam · 2009-01-07 23:58

·This what you need to do what you want to DO
·

' -----[noparse][[/noparse] Initialization ]--------------------------------------------------
Init:
  reg = CWPr                            ' Initialize DS1302
  ioByte = WPr0                         ' Clear Write Protect
  GOSUB RTC_Out                         ' Send Command
 
  reg = %10010000
ioByte = %10101001
GOSUB RTC_Out
 
 
  reg = $8A          ' Point to register 8Ah
ioByte = %00000000 ' initializes the clock days to "00"
GOSUB RTC_Out      ' Send Command

 reg = $84          ' Point to register 84h
ioByte = %00000000 ' initializes the clock in 24 hour mode and clear the hours to "00"
GOSUB RTC_Out      ' Send Command

reg = $82          ' Point to register 82h
ioByte = %00000000 ' clear the minutes to "00"
GOSUB RTC_Out      ' Send Command

reg = $80          ' Point to register 80h
ioByte = %00000000 ' starts the clock by clearing the Clock Halt bit and clears the Seconds to "00"
GOSUB RTC_Out      ' Send Command
--------------------------------------------------------------------------------------------- 
This will need to be running in a routine to keep the clock stop at the time that you want 
----------------------------------------------------------- 
Halt_clock:
 reg = $80          ' Point to register 80h
 ioByte = %10000000 ' Set Clock Halt Bit
 GOSUB RTC_Out      ' Send Command
 RETURN
 
-----------------------------------------------------------This only need to runned one time to restart the clock 
----------------------------------------------------------- 
Restart_clock:
 reg = $80          ' Point to register 80h
 ioByte = %0110000 ' starts the clock by clearing the Clock   'Halt bit and clears the minutes to "00"
 GOSUB RTC_Out      ' Send Command
 RETURN

·Here is where I used in a Project @ this Post
http://forums.parallax.com/showthread.php?p=737892

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··Thanks for any·

·that you may have and all of your time finding them

·
·
·
·
Sam

Post Edited (sam_sam_sam) : 1/8/2009 12:15:45 AM GMT

techstudent · 2009-01-08 00:31

Thanks for the quick reply, I failed to mention in the original post that I also wanted to record a time and date for when the event occurred, but it may just be a lot easier to use two RTC, one for recording the time/day, and the other as the stopwatch using the code posted above... thanks again, I think I will get to ordering another DS1302

sam_sam_sam · 2009-01-08 01:49

 ' -----[noparse][[/noparse] Initialization ]--------------------------------------------------

Init:
  T_reg = T_CWPr                            ' Initialize DS1302
  T_ioByte = T_WPr0                         ' Clear Write Protect
  GOSUB T_RTC_Out

  E_reg = E_CWPr                            ' Initialize DS1302
  E_ioByte = E_WPr0                         ' Clear Write Protect
  GOSUB E_RTC_Out                         ' Send Command

  T_reg = %10010000
T_ioByte = %10101001
GOSUB T_RTC_Out

 E_reg = %10010000
E_ioByte = %10101001
GOSUB E_RTC_Out

T_reg = $86          ' Point to register 86
T_ioByte = %00000000 ' initializes the clock date to "00"
GOSUB T_RTC_Out      ' Send Command

  T_reg = $8A          ' Point to register 8Ah
T_ioByte = %00000000 ' initializes the clock days to "00"
GOSUB T_RTC_Out      ' Send Command

 T_reg = $84          ' Point to register 84h
T_ioByte = %00000000 ' initializes the clock in 24 hour mode and clear the hours to "00"
GOSUB T_RTC_Out      ' Send Command

T_reg = $82          ' Point to register 82h
T_ioByte = %00000000 ' clear the minutes to "00"
GOSUB T_RTC_Out      ' Send Command

T_reg = $80          ' Point to register 80h
T_ioByte = %00000000 ' starts the clock by clearing the Clock Halt bit and clears the Seconds to "00"
GOSUB T_RTC_Out      ' Send Command

  E_reg = $86          ' Point to register 86
E_ioByte = %00000000 ' initializes the clock date to "00"      0 to 31
GOSUB E_RTC_Out      ' Send Command

E_reg = $8A          ' Point to register 8Ah
E_ioByte = %00000000 ' initializes the clock days to "00"      0 to 7
GOSUB E_RTC_Out      ' Send Command

E_reg = $88          ' Point to register 88h
E_ioByte = %00000000 ' clear the months to "00"                0 to 12
GOSUB E_RTC_Out      ' Send Command

 E_reg = $84          ' Point to register 84h
E_ioByte = %00000000 ' initializes the clock in 24 hour mode and clear the hours to "00"
GOSUB E_RTC_Out      ' Send Command

E_reg = $82          ' Point to register 82h
E_ioByte = %00000000 ' clear the minutes to "00"
GOSUB E_RTC_Out      ' Send Command

E_reg = $80          ' Point to register 80h
E_ioByte = %00000000 ' starts the clock by clearing the Clock Halt bit and clears the Seconds to "00"
GOSUB E_RTC_Out      ' Send Command

Here what you have to do if you use two DS1302 time chips

One word of caution you will run out of memory very fast if you are not ·careful how you write your code routine this happen to when writing this code using two time chip if you want to keep track of total timed
event

If you can find a way to use the DS1302 Ram to save these values Please Post Your Code
I would like to see it when your done

Here is the code where Rev the frist code

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··Thanks for any·

·that you may have and all of your time finding them

·
·
·
·
Sam

Post Edited (sam_sam_sam) : 1/8/2009 2:00:55 AM GMT

techstudent · 2009-01-08 04:09

Wow, thanks for all the help Sam, I won't have time work through it all for a couple of days, but if I figure out anything about utilizing the DS1302 Ram I will let you know... I also appreciated seeing your project and all the pics/schematics thanks again..

~techstudent

Tracy Allen · 2009-01-08 17:38

Another way to approach this with is to compute the elapsed time from the real time. Read hours and minutes from the DS1302, then:

julian0 = hours.nib1 * 10 + hours.nib0 * 6 + minutes.nib1 * 10 + minutes.nib0

That converts the HEX2 into a number that goes straight from 0 to 1439 as time goes from 00:00 to 23:59. The format from the clock is actually called BCD (binary coded decimal), which is similar to HEX, but as you noticed, it includes only digits 0 to 9 and not A to F. The above calculation goes strictly left to right (no precedence for multiplication, a peculiarity of Stamp math).

At the end of the time interval you calculate again

julian1 = hours.nib1 * 10 + hours.nib0 * 6 + minutes.nib1 * 10 + minutes.nib0

Then

elapsed = julian1 - julian0 + 1440 // 1440

The purpose of +1440//1440 is to account for possible transitions past midnight, positive definite.

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Tracy Allen
www.emesystems.com

Chris Savage · 2009-01-08 18:29

One method I have used to calculate elapsed time is to simply increment or decrement a separate counter when the seconds register changes. This has several advantages…first of all it does not interfere with the normal functions of the RTC. You can set the date/time normally and access them at any time.

Another benefit is you can have multiple counters, each with a resolution of 1 second. These can count up (like a stopwatch) or down (like a count-down timer) and can occur concurrently with each other. If you like each can be enabled/disabled via flag variable.

Basically all you do is in your main loop when you need to count, each time the seconds change you update your counters as well as the old seconds value. This happens each iteration at exactly 1 second intervals and allows for many other events to happen between the changes, such as updating the enabled (if you use that) counters and activating any sort of indication of a completed event (or logging the date/time). I hope this helps. Take care.

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Chris Savage
Parallax Engineering

fsb · 2011-03-24 12:48

Chris,
seems like this is exactly what I need to do, but I am not experienced enough to figure out the code. What I am trying to do is have my camera take pictures at defined intervals (e.g every hour or once every 24 hrs). I would like to use the DS1302 as a count up clock, and at the appropriate intervals, trigger the picture. Can you give me an example of code on how to implement that with the DS1302?

Thanks

sam_sam_sam · 2011-03-24 13:20

Try this , this is once every hour

' -----[ Program Code ]----------------------------------------------------
Start:
hrs  = $00
mins = $00
secs = $00
GOSUB Set_Time
DO
LOW 0
GOSUB Get_Time
DEBUG HOME, HEX2 hrs, ":",   HEX2 mins, ":", HEX2 secs
IF hrs = $00 AND mins = $59 AND secs = $00 THEN EXIT
LOOP
DEBUG CR, CR, "00:59:00 Elapsed"
HIGH 0
PAUSE 100
GOTO start

' =========================================================================
'
'   File...... DS1302_Demo.bs2
'   Purpose... Demonstrate The DS1302 Clock & RAM Functions
'   Author.... Chris Savage -- Parallax, Inc.
'   E-mail.... [EMAIL="csavage@parallax.com"]csavage@parallax.com[/EMAIL]
'   Started...
'   Updated... 10-09-2005
'
'   {$STAMP BS2}
'   {$PBASIC 2.5}
'
' =========================================================================
 
' -----[ Program Description ]---------------------------------------------
' This code demonstrates the use of the DS1302 RTC/RAM Chip with the BASIC
' Stamp 2 Microcontroller, making easy use of the 12 Hour & 24 Hour time
' modes, as well as accessing the RAM.  The sample code will use the DEBUG
' window for input and output for simplicity.  You can change the output
' to the device of your choice.  For example, using a Parallax Serial LCD
' requires very few changes to the code to use it for output.
' A modified version of this code was adapted to display the date and time
' on a Parallax Serial LCD Display (#27976), also with backlight (#27977)
' and on Parallax Professional Development Board (#28138, coming soon!)
' using a MAX7219 8-Digit Display Driver.
' This code will work on all BS2 Stamp Modules.
'
' The Parallax 2 X 16 Serial LCD Displays are availble at the following
' links:
' [URL]http://www.parallax.com/detail.asp?product_id=27976[/URL]
' [URL]http://www.parallax.com/detail.asp?product_id=27977[/URL]
'
' Pin Assignments
' 0   DS1302 DataIO
' 1   DS1302 Clock
' 2   DS1302 Chip Select
 
' -----[ Revision History ]------------------------------------------------
 
' -----[ I/O Definitions ]-------------------------------------------------
DataIO          PIN     4               ' DS1302.6
Clock           PIN     3               ' DS1302.7
CS1302          PIN     5               ' DS1302.5
 
' -----[ Constants ]-------------------------------------------------------
WrSecs          CON     $80             ' Write Seconds
RdSecs          CON     $81             ' Read Seconds
WrMins          CON     $82             ' Write Minutes
RdMins          CON     $83             ' Read Minutes
WrHrs           CON     $84             ' Write Hours
RdHrs           CON     $85             ' Read Hours
CWPr            CON     $8E             ' Write Protect Register
WPr1            CON     $80             ' Set Write Protect
WPr0            CON     $00             ' Clear Write Protect
WrBurst         CON     $BE             ' Write Burst Of Data
RdBurst         CON     $BF             ' Read Burst Of Data
WrRam           CON     $C0             ' Write RAM Data
RdRam           CON     $C1             ' Read RAM Data
 
' -----[ Variables ]-------------------------------------------------------
index            VAR     Byte            ' Loop Counter
reg               VAR     Byte            ' Read/Write Address
ioByte           VAR     Byte            ' Data To/From DS1302
secs             VAR     Byte            ' Seconds
secs01          VAR     secs.LOWNIB
secs10          VAR     secs.HIGHNIB
mins             VAR     Byte            ' Minutes
mins01          VAR     mins.LOWNIB
mins10          VAR     mins.HIGHNIB
hrs                VAR     Byte            ' Hours
hrs01            VAR     hrs.LOWNIB
hrs10            VAR     hrs.HIGHNIB
date             VAR     Byte
month           VAR     Byte
day              VAR     Nib             ' Day
year             VAR     Byte            ' Year
 
work            VAR     Byte            ' Work Data
 
' -----[ Initialization ]--------------------------------------------------
Init:
  reg = CWPr                            ' Initialize DS1302
  ioByte = WPr0                         ' Clear Write Protect
  GOSUB RTC_Out                         ' Send Command
 
' -----[ Program Code ]----------------------------------------------------
Start:
hrs   = $00
mins = $00
secs = $00
GOSUB Set_Time
DO
 LOW 0
  GOSUB Get_Time
 DEBUG HOME, HEX2 hrs, ":",  HEX2 mins, ":", HEX2 secs
  IF hrs = $00 AND mins = $59 AND secs = $00 THEN EXIT
LOOP
DEBUG CR, CR, "00:59:00 Elapsed"
HIGH 0
PAUSE 100
GOTO start
' -----[ Subroutines ]-----------------------------------------------------
 
RTC_Out:
  HIGH CS1302                           ' Select DS1302
  SHIFTOUT DataIO, Clock, LSBFIRST, [reg, ioByte]
  LOW CS1302                            ' Deselect DS1302
  RETURN
RTC_In:
  HIGH CS1302                           ' Select DS1302
  SHIFTOUT DataIO, Clock, LSBFIRST, [reg]
  SHIFTIN DataIO, Clock, LSBPRE, [ioByte]
  LOW CS1302                            ' Deselect DS1302
  RETURN
Set_Time:                               ' DS1302 Burst Write
  HIGH CS1302                           ' Select DS1302
  SHIFTOUT DataIO, Clock, LSBFIRST, [WrBurst]
  SHIFTOUT DataIO, Clock, LSBFIRST, [secs, mins, hrs,
    date, month, day, year, 0]
  LOW CS1302                            ' Deselect DS1302
  RETURN
Get_Time:                               ' DS1302 Burst Read
  HIGH CS1302                           ' Select DS1302
  SHIFTOUT DataIO, Clock, LSBFIRST, [RdBurst]
  SHIFTIN DataIO, Clock, LSBPRE, [secs, mins, hrs, date, month, day, year]
  LOW CS1302                            ' Deselect DS1302
  RETURN

I hope this helps

fsb · 2011-03-24 19:49

Thanks, sam, that was really helpful to me.

Here's what I did so far, using Chris's DS1302 template and ideas I gleaned from your response.

I can adjust time for exposure (shutter speed of camera) and interval the photos are taken.

The one last thing I would like to do is be able to stop the program after a certain period of time. Is there a way the program can count the number of iterations that the program completes from the start: portion through the goto start portion?

fsb

sam_sam_sam · 2011-03-25 05:52

fsb wrote: »

The one last thing I would like to do is be able to stop the program after a certain period of time. fsb

Please explain in more detail what you want to do here

Are you wanting to stop the " Timer "for some amount of time ?
or
Do you want to wait for some amount of time before the your code routine run again ?

What you have to do is different in the way you write the code for the first question vers the second question

fsb · 2011-03-25 09:05

Thanks sam.

I am trying to stop the process after a certain amount of time. For instance, if I am taking a picture every hour, I would, for instance, want to stop after 48 hrs. This would be 48 iterations of the program. Not sure if BS2 can do something like that. May have to learn spin

fsb

sam_sam_sam · 2011-03-25 09:59

 
 ' -----[ Program Code ]----------------------------------------------------
Start:
mins = $00
secs = $00
GOSUB Set_Time
DO
 LOW 0
  GOSUB Get_Time
 DEBUG HOME,HEX2 hrs, ":", HEX2 mins, ":", HEX2 secs
  IF mins = $59 AND secs = $00 THEN GOSUB routine1:
  IF  THEN EXIT
  ENDIF
LOOP
 
DEBUG CR, CR, "48:00:00 Elapsed"
 
 
 
' -----[ Subroutines ]-----------------------------------------------------
routine1:
DEBUG CR, CR, "00:59:00 Elapsed"
HIGH 0
PAUSE 100
RETURN

OR

'
' -----[ Variables ]-------------------------------------------------------  
'
' 
iteration       VAR     Byte                 
' 
' 
' -----[ Program Code ]----------------------------------------------------
Start:
mins = $00
secs = $00
GOSUB Set_Time
 
iteration_set:
DO
LOW 0
GOSUB Get_Time
DEBUG HOME,HEX2 hrs, ":", HEX2 mins, ":", HEX2 secs
IF mins = $59 AND secs = $00 THEN GOSUB routine1:
IF iteration = 48 THEN EXIT
ENDIF
LOOP
'Your code here
GOTO start
' -----[ Subroutines ]-----------------------------------------------------
 
Routine1:
DEBUG CR, CR, "00:59:00 Elapsed"
HIGH 0
iteration = iteration + 1
PAUSE 100
RETURN

sam_sam_sam · 2011-03-25 10:21

Start:
iterations  = 00
hrs  = $00
mins = $00
secs = $00
GOSUB Set_Time 'starts timer from zero
    DO
       GOSUB Get_Time 'moniters timer
 
 
       DEBUG HOME, HEX2 mins, ":", HEX2 secs
 
       IF hrs = int_hr AND mins = int_min AND secs = int_sec THEN EXIT   
                                                    '  ^ < .......You need to change this to a subroutine not EXIT ......> 
    LOOP
        HIGH led
        PAUSE exp_time
        LOW led
      iterations =  iterations + 1                ' <............ For this line to work the way you want this to work
    GOTO start

Something like this

DO
GOSUB Get_Time 'moniters timer
 
 
DEBUG HOME, HEX2 mins, ":", HEX2 secs,DEC2 ? iterations
 
IF hrs = int_hr AND mins = int_min AND secs = int_sec THEN GOSUD routine_1
IF iterations = 48 THEN EXIT 
 
LOOP
 
GOTO start
 
 
Routine_1: 
HIGH led
PAUSE exp_time
LOW led
iterations = iterations + 1
RETURN

I hope this helps

fsb · 2011-03-25 11:35

Thanks

I will try this

fsb

sam_sam_sam · 2011-03-25 14:45

I do want you to know that could have the DS1302 ram save your setting when have the Basic Stamp powered down
If you need help with this Please ask and I will help you as much as I can how ever I do not have one set to test the code right now but it is not hard to do

This is some thing a little while ago so might give you idea what can be done

For the DS1302 to save your data all you need a 1 MFD super cap to do this with this set up it would hold you data for more than a week

Here is where you buy a MFD super cap

http://www.allelectronics.com/make-a-store/item/CBC-17/1-FARAD-5.5-VOLT-SUPER-CAP//1.html

WriteRam:                                        ' Routine to Save Data to a DS1302 Time Chip
                                ' Send Command
  reg = $FE
  HIGH Timer
  SHIFTOUT DataIO, Clock,LSBFIRST, [reg]
  SHIFTOUT DataIO, Clock, LSBFIRST, [PDSecs.HIGHBYTE,PDSecs.LOWBYTE,SLSecs.HIGHBYTE,SLSecs.LOWBYTE,S,M,H,T]
  LOW Timer
  RETURN
  ReadRam :                           'Routine to Read Data from DS1302 Time Chip
  reg = $FF
  HIGH Timer
  SHIFTOUT DataIO, Clock, LSBFIRST, [reg]
  SHIFTIN DataIO, Clock, LSBPRE, [PDSecs.HIGHBYTE,PDSecs.LOWBYTE,SLSecs.HIGHBYTE,SLSecs.LOWBYTE,S,M,H,T]
  LOW Timer
  DEBUG HOME, "Product = ",DEC5  PD,"  Silo = ",DEC5 SL, CR, CR,
                           DEC5 ? PDSecs, DEC5 ? SLSecs,CR
 
  DEBUG   DEC2  T, " T ",CR, CR, " H = ", DEC2  H, " M = ",
          DEC2  M," S = ", DEC2  S
 
 
Metered:
  GOSUB ReadRam
 
PD = PDsecs + (PDsecs ** 13741)  ' Caculate Sand used from Sand Silo
SL = SLsecs + (SLsecs ** 13741)
 
T = (SL/500) * 1               ' T = Caculate percentage of product used
 
'S = seconds                  ' Timer Counter Names are one letter because there is not enough-
'M = Minutes                  ' -space to show all Data on LCD Display
'H = Hours
 
IF s = 60 THEN
 S = 00
 M = M + 1
 IF M = 60 THEN
 M = 00
 H = H + 1
 ENDIF
 ENDIF
 
IF oldsecs <> secs THEN      ' This Routine Compars the oldsecs to secs
   oldsecs = secs            ' This Routine is so that Counter Update once a Seconds
   S = S + 1                 ' This for the Timer Counter for the amount of time  has that been used by the Sand Silo
   PDSecs = PDSecs + 1
   SLSecs = SLSecs + 1
ENDIF
GOSUB WriteRam
RETURN

DS1302 measuring elapsed time (stop watch) ?

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