Timer comparison on a PIC in assembly - Electronic Circuits Projects Diagrams Free

marting · 1st December 2005, 11:01 AM

Hi,

I am strugling with a problem on a PIC. I have an app written in ASM that is used as a timer module. It has a build in klok, and a user config. timer.
The problem I face is that I cannot get the ASM routine to check if the current time is between the on/off time of the timer (so it will turn on a output).

I made one solution with a litteral register (in which the values of the time and timer are stored) comparison, and that works fine, until you change the timer setting. In that case it will only get active the next time (so this could be a day) the litteral comparisson succeeds.

What acctually is going wrong is that fact that a timer setting can be set over midnight. Ie.

T-On = 17:00
T-Off = 23:00
this works without any problem..but this is what I stuck on:

T-On = 17:00
T-Off = 02:00

(remember when comparing the time, you are only using 00-23 ..)
I would prefer a hint in ASM, but a flowchart might work as well..

Thanks

Pommie · 1st December 2005, 11:17 AM

Why not check if the on time is after the off time and reverse your comparison. That is, check if it is between the off times.

So, with your examples.

T-On = 17:00
T-Off = 23:00

You say this works fine and so I assume you can check if the current time is greater than T-On and less than T-Off. If it is then your timer is ON.

T-On = 17:00
T-Off = 02:00

With this example, because T-On if greater than T-Off, check if the current time is greater then T-Off and less than T-On. If it is then your timer is OFF.

HTH

Mike.

marting · 1st December 2005, 11:35 AM

Hi mike,

Think its just the push I needed.. Ive made simple if..then statement.
I bvelieve this should do the trick?

l = 1

If ton > toff Then
If h > toff And h < ton Then
l = 0
End If
Else
If h < ton Or h > toff Then
l = 0
End If
End If

Pommie · 1st December 2005, 12:17 PM

I think your nearly there.

in basic it would be

Code:

If Ton > Toff then
	l = 1
	if h > Toff and h < Ton then
		l=0
	endif
else
	l = 0
	if h > Ton and h < Toff then
		l=1
	endif
endif

Mike.
Edit just trying something.
㏀㎌

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

1st December 2005, 11:01 AM	(permalink)
marting	Timer comparison on a PIC in assembly Hi, I am strugling with a problem on a PIC. I have an app written in ASM that is used as a timer module. It has a build in klok, and a user config. timer. The problem I face is that I cannot get the ASM routine to check if the current time is between the on/off time of the timer (so it will turn on a output). I made one solution with a litteral register (in which the values of the time and timer are stored) comparison, and that works fine, until you change the timer setting. In that case it will only get active the next time (so this could be a day) the litteral comparisson succeeds. What acctually is going wrong is that fact that a timer setting can be set over midnight. Ie. T-On = 17:00 T-Off = 23:00 this works without any problem..but this is what I stuck on: T-On = 17:00 T-Off = 02:00 (remember when comparing the time, you are only using 00-23 ..) I would prefer a hint in ASM, but a flowchart might work as well.. Thanks

1st December 2005, 11:17 AM	(permalink)
Pommie	Why not check if the on time is after the off time and reverse your comparison. That is, check if it is between the off times. So, with your examples. T-On = 17:00 T-Off = 23:00 You say this works fine and so I assume you can check if the current time is greater than T-On and less than T-Off. If it is then your timer is ON. T-On = 17:00 T-Off = 02:00 With this example, because T-On if greater than T-Off, check if the current time is greater then T-Off and less than T-On. If it is then your timer is OFF. HTH Mike.

1st December 2005, 11:35 AM	(permalink)
marting	Hi mike, Think its just the push I needed.. Ive made simple if..then statement. I bvelieve this should do the trick? l = 1 If ton > toff Then If h > toff And h < ton Then l = 0 End If Else If h < ton Or h > toff Then l = 0 End If End If

1st December 2005, 12:17 PM	(permalink)
Pommie	I think your nearly there. in basic it would be Code: If Ton > Toff then l = 1 if h > Toff and h < Ton then l=0 endif else l = 0 if h > Ton and h < Toff then l=1 endif endif Mike. Edit just trying something. ㏀㎌ Last edited by Pommie; 6th November 2006 at 05:51 AM.