touble with a time calculation

[longpole001]

the isr updates EL0,EL1 , EL2 during the call

the isr reloads timer1 every 10ms , then updates EL0-2 variables during that call and displaying them take time ,

a long as the running display is clearly correct for EL2 =EL1 - set_times for sec,min, hour ,day , then i think it be ok.

at the moment its just show the totaly wrong values for duration of the set time

[longpole001]

thanks guys

ill try both ways i rather not have wrong calculations but i also know this interupt is serviced every 10ms , and the E0-2 varables should be correct for that amount of time ??

[richard]

that's the wrong way to think about it , you can never know when the 10ms period will start or finish , this way is better.
the interrupt latency with a 32mHZ clk will be about 10uS anyway , time to copy 4 bytes to a buffer say 4 uS , the interrupt will only be deferred 4uS plus another couple for the int disable enable worst case you'll hardly notice

[longpole001]

hI GUYS , using the code by steve seems to work , a small change cos i use EL1 values to show the current time value , so any changes that change the EL1 values in the calculating the EL2 , is not possible so i need to copy the values of EL1 to EL3 , then use EL3 as a temp group

I am trying to disable the interupt whilest in the ISR subroutine , before the copy of EL0 to EL1-3 , then re -enable interrupt after ,

but i get a interrupt priority state not found error when compile atm

[richard]

it serves no purpose to stop the isr from within the isr , its a waste of time copying the el vars to a buffered copy inside the isr .
time in your case is in essence a multi byte var , the value is volatile and cannot be guaranteed outside the isr when the isr is running.
the correct procedure is
disable isr
copy bytes to buffer
enable isr
do your subtraction

[longpole001]

ok done that , cheers

[longpole001]

steve was wodering what the code may be if i was to use the el1 values plus event1 setting to the overrun point , and use say event 2 seting to show the amount time left before overrun , eg EL0 is counting up , copied to EL1 for display , Event 1 setts time for the overrun , Event2 sets time to show time before reching the overrun time , EL3 displays the time counting down to reach time set by Event1 time.

[EarlyBird2]

Probably easy to do. Post some code from the relevant section for me to look at.

[longpole001]

ok well EL0 is counting up , EL1 and EL3 are copys of EL0
EL4 is the time left in the event

Event1_OT = time duration of event
Event2_OT = Time when to display the timeleft clock
i
f EVent1_OT all 0 then disable time left clock
if Event2_OT all 0 then no timeleft clock

Event2_OT can not be > Event1_OT set time

 if  Event1_OT_Day = 0 and Event1_OT_hour  = 0 and Event1_OT_Min = 0 and _            ' if all values are 0 , then dont enable the overrun timer 
        Event1_OT_sec = 0 and Event1_OT_100th = 0 then 
          EL2_Enable = 0 ' Disable El2 Counter   
          EL2_Allow = 0  ' clear Flag so EL4 wont start   
    else
          EL2_Allow = 1  ' Event1 setting Higher than 0 so allow EL4 to be enabled if Event2 settings are higher than 0 
    endif
    

' ---------------------

 if  Event2_OT_Day = 0 and Event2_OT_hour  = 0 and Event2_OT_Min = 0 and _  
       Event2_OT_sec = 0 and Event2_OT_100th = 0 then 
         EL4_Allow = 0  ' disable Event End Timer - EL4 
   else
         EL4_Allow = 1  ' Allow Event End Timer - EL4 
   endif 
   if EL2_Allow = 1 and EL4_Allow = 1 then                        ' if Event1 times set and Event2 times set then allow EL4_enable to start Event End timer 
      
       if EL1_Days    <= Event2_OT_Day and EL1_Hours   <= Event2_OT_Hour and _
          EL1_Minutes <= Event2_OT_Min and EL1_Seconds <= Event2_OT_Sec  and _
          EL1_100th   <= Event2_OT_100th then EL4_Enable = 1                                ' show clock when time left in event

all i have so far

[EarlyBird2]

Have you got any further?