Expanding Timer1 counting range

[Acetronics2]

You just need to preload Timer 1 with a value "not so far" from 65536 - 1000 ... no more free running timer usable !!!

it will overflow for 1000 counts = 1 ms ...

"not so far" mean you have to add the time to reload the timer and do what you want to the "64536" value ...

See Steve's ( Mr E !!! ) calculator here : http://www.mister-e.org/pages/utilitiespag.html


I also forgot you could use the "compare" function of the CCP module ... and poll the CCPIF bit !

Alain

[sycluap]

Yeah, I did make TMR1H = $FC, TMR1L=$18, which is obtained from 65536-1000. But the timer does not give me 1ms interval. I do not know what is wrong. Below is my program:

'MAIN PROGRAM
'------------
ResetTimer:
GoSub SetReg
LCDOUT $FE, 1
Timer1H = 0
Timer1L = 0
Result = 0
TimerOverflow = 0

Main:
LCDOUT $FE, $80, "Test Mode 1"
LCDOUT $FE, $C0, "Visual Response Test"
If ButStart = 1 Then goto StartTimer
Goto Main

StartTimer:
LCDOUT $Fe, 1
LCDOUT $FE, $80, "Calculating..."
T1CON.0=1

Looping:
While PIR1.0=0
Wend
PIR1.0=0
TimerOverflow=TimerOverflow+1
LCDOUT $FE,$C0,DEC5 TimerOverFlow
If ButStop = 1 Then goto StopTimer
Goto Looping

StopTimer:
T1CON.0 = 0
LCDOUT $Fe, 1
GoSub GetValue

DisplayResult:
Result = TimerOverflow
LCDOUT $FE,$C0, dec5 Result
If ButStart = 1 Then goto StartTimer
If ButReset = 1 Then goto ResetTimer
goto DisplayResult


'SUBROUTINES
'===========
'Reset Timer1 Register to Start from 1ms interval
'-------------------------------------------------------
SetReg:
TMR1H = $FC
TMR1L = $18
Return

Is there anything wrong with the program that cause the Timer unable to display 1ms interval timing on LCD?

[Acetronics2]

Your LCD display is unable to show time for EACH ms ... the LCDOUT command needs much more thant 1 ms - OR you should use LED Display ...

With that way of programming You might have enough time to refresh the display between two interrupts ...

Here, to be accurate ... you just can display exact time ONLY once timer stopped !!!


see How Darrel's "Elapsed timer Demo " works ... and you will be able to see "intermediate time"

http://www.picbasic.co.uk/forum/show...=Elapsed+timer


Alain

PS: you can read the ms "on the fly" .... Wooowww !!! you got a fantastic pair of eyes !!!
LOL ...

[sycluap]

The additional line of code after the clear overflow flag is to test the timer whether the timing is accurate or not. Let's say of ms can't be seen, but at least for the seconds can be seen accurately right? Previously the coding was to display the final value directly on the LCD after Stop button is pressed. Conclusion is, I wonder the 1ms interval can be achieved or not.

From my codes structure, is achieving 1ms interval timing possible? Is there any modification need to be carried out besides displaying final timing value on LCD, in order to achieve 1ms interval timing?

[skimask]

Your LCD display is unable to show time for EACH ms ... the LCDOUT command needs much more thant 1 ms - OR you should use LED Display ...

Actually, most of the LCDs I've got, usually the 16x2, are able to handle a commandus of around 100 and a dataus of 50 (the best one I've got will do commandus = 50 and dataus = 27, well below that datasheet values).
So, assuming you don't have too much to display, theoretically, you could refresh one complete line on a 16x2 LCD inside of 1ms...assuming that is

(and I knew this thread was coming)

[sycluap]

Is that mean the culprit for unable to get 1ms interval timer is the LCD display? What is I just make it display the final value upon stop button is pressed? Can this solve the problem?

[skimask]

Is that mean the culprit for unable to get 1ms interval timer is the LCD display? What is I just make it display the final value upon stop button is pressed? Can this solve the problem?

Are you completely incapable of doing any 'out of the box' thinking? Kick your brain into gear! Just because the LCD takes longer than 1ms to display (which is not necessarily true, but at default settings is true), doesn't mean the PIC can't keep counting until you stop it from counting and then displaying the result when it is done counting.
What are you counting that supposedly requires microsecond accuracy anyways?

[sycluap]

Not that I can't think out of the box, but I've asked around and tried whatever is possible, to display counting in LCD, not to display in LCD, to display only the final value, etc, but i still can't manage to get the timer to display in 1ms timing interval. I know that the PIC can continue counting by itself, but, even I try to make it display only the final value, but it still can't display the accurate readings.

Sorry for asking questions that might consider too easy for some others, but I am totally new in this. I need the timer to measure the human response time.

MY CODE:

'MAIN PROGRAM
'------------
ResetTimer:
GoSub SetReg
LCDOUT $FE, 1
Timer1H = 0
Timer1L = 0
MicroThousandths = 0
Thousandths = 0
Hundredths =0
Seconds = 0

Main:
LCDOUT $FE, $80, "Test Mode 1"
'LCDOUT $FE, $C0, "Visual Response Test"
If ButStart = 1 Then goto StartTimer
Goto Main

StartTimer:
LCDOUT $Fe, 1
LCDOUT $FE, $80, "Calculating..."
T1CON.0=1

Looping:
While PIR1.0=0
Wend
PIR1.0=0
Thousandths=Thousandths+1
If Thousandths>9 Then
Thousandths=0
Hundredths=Hundredths+1

If Hundredths>99 Then
Hundredths=0
Seconds=Seconds+1
Endif
Endif

If ButStop = 1 Then goto StopTimer
Goto Looping

StopTimer:
T1CON.0 = 0
LCDOUT $Fe, 1
GoSub GetValue

DisplayResult:
LCDOUT $FE, $80, "Time Elapsed"
LCDOUT $FE,$C0, dec2 Seconds, ".", dec2 Hundredths, ":", dec Thousandths
If ButStart = 1 Then goto StartTimer
If ButReset = 1 Then goto ResetTimer
goto DisplayResult


'SUBROUTINES
'===========
'Get value from Timer1 Register
'------------------------------
GetValue:
Timer1H=TMR1H
Timer1L=TMR1L
Return

'Reset Timer1 Register to Start from 1ms interval
'-----------------------------------------
SetReg:
TMR1H = $FC
TMR1L = $18
Return

Now, what is wrong with my codes? Correct me please.