Using Pic as a digital clock/timer. How accurate?

[rocky79]

Hello,
I am trying to use the pic as a clock timer that displays the time hour and minutes but also i would like it to have a featured timer that the user can set. The timer will activate a motor.
will the time be accurate enough?
I am using the pic basic pro and the usb programmer.
What's the easiest way to get this done? any suggestions is appreciated.
Thanks

[SteveB]

Bottom line - It will only be as accurate as the oscillator used. The PIC is not the limiting factor.

SteveB

[fazan83]

Hello,
I am trying to use the pic as a clock timer that displays the time hour and minutes but also i would like it to have a featured timer that the user can set. The timer will activate a motor.
will the time be accurate enough?
I am using the pic basic pro and the usb programmer.
What's the easiest way to get this done? any suggestions is appreciated.
Thanks

I give u example of simple timer and clock where user can set when they want to high certain port of the PIC. THere is only two buttons need to be used. First button to toggle from one menu to other menu. For example if we press this button then we can change from setting minute to the hour setting menu. Other button function is to set(increase) the value of second, minute, hour and etc. But how accurate this timer is depend on the oscillator u use as Steve B had said before. Attached herewith is the code: Please advise if you have some input on this code. Thanks.

symbol second=2000
symbol second2=1000

second1 VAR BYTE
minute VAR BYTE
hour VAR BYTE
day VAR BYTE
time1 VAR BYTE
time2 VAR BYTE

second1=0
minute=0
hour=0
day=0
time1=0
time2=0
masa3=0


hourset:
Pause 200
LCDOut $FE,1
LCDOut "Set Hour"
LCDOut $FE,$C0
LCDOut "TIME:",DEC2 day,".",DEC2 hour,".",DEC2 minute,".",DEC2 second

IF PORTB.5=1 Then GoSub addhour
IF hour>23 Then hour=0
IF PORTB.6=1 Then GoSub time1set
GoTo hourset

hour1set:
Pause second2
LCDOut $FE,1
LCDOut "Set Time MotorOn1"
LCDOut $FE,$C0
LCDOut "Minute:",DEC2 time1

IF PORTB.5=1 Then GoSub addtime1
IF time1>59 Then time1=0
IF PORTB.6=1 Then GoSub time2set
GoTo time1set

time2set:
Pause second2
LCDOut $FE,1
LCDOut "Set Time MotorOn2"
LCDOut $FE,$C0
LCDOut "Day:",DEC2 time2

IF PORTB.5=1 Then GoSub addtime2
IF time4>99 Then time2=0
IF PORTB.6=1 Then GoSub changeday
GoTo time2set
End

addhour:
IF PORTB.5=1 Then GoSub timer
Return

timer:
second1=0
minute=minute+1
IF minute > 59 Then
minute=0
hour=hour+1
IF hour >23 Then
hour=0
day=day+1
IF day>30 Then
dayi=0
EndIF
EndIF
EndIF
Pause 500
Return

addtime1
IF PORTB.5=1 Then time1=time1+1
Pause 500
Return

addtime2
IF PORTB.5=1 Then time2=time2+1
Pause 500
Return

changeday:
IF PORTB.6=1 Then GoTo day


day:
Pause second
saat=saat+1
IF second1 >59 Then GoSub timer


LCDOut $FE,2
LCDOut "ON:",DEC2 time1,">",DEC2 time2,">"
LCDOut $FE,$C0
LCDOut "TIME:",DEC2 day,".",DEC2 hour,".",DEC2 minute,".",DEC2 second1


IF (minute=time1 OR minute=time2) Then High PORTB.7
IF (minute=time1+1 OR minute=time2+1) Then Low PORTB.7
Goto day

[rocky79]

Thanks Fazan for the code but one thing i didn't understand is how do i get the actual seconds by simply counting? if you count from 1 to 60 does it mean its 1 to 60seconds? can you clarify how you convert from the simple execution time for the count to actual seconds.
Thanks a lot

[paul borgmeier]

Another Option - might help get you started
http://www.picbasic.co.uk/forum/showthread.php?t=2129

[fazan83]

Thanks Fazan for the code but one thing i didn't understand is how do i get the actual seconds by simply counting? if you count from 1 to 60 does it mean its 1 to 60seconds? can you clarify how you convert from the simple execution time for the count to actual seconds.
Thanks a lot

How accurate it is depend on the speed of oscillator that u use.

[sayzer]

Also, the ambient temp is the most effective factor.

You can get a slow running or fast running clock ticks depending on the temperature of the environment in which your PIC is running. (ambient temp)

--------------------------

[Acetronics2]

Hi, Rocky

I just built Thermo-baro-clock with a MS5534 sensor.( 16F876 ) the clock is driven by a 32.7... khz "clock crystal" connected to RC0,RC1 pins and using TMR1 ovf interrupt.

The only way to adjust reading is to trim the TMR1 preset ( 32768 ...in theory ). an adjustable capacitor parallelled to one of the xtal load caps could also help a bit.

Possible also to use two pushbuttons to inc/dec the TMR preset value, you then store in the EEPROM ... but do not forget to limit the trim range !!!

But as always ... no simple automatic trimming.

Absolute references will always be our main headaches ... cause there's none naturally existing !!!

best regards
Alain