tmr2 interrupt problem

[mister_e]

To measure how long a single code line or chunk of code need toexecute, you have several method
1: Scope method
you Set/Clear an I/O before and after a code chunk, then you measure it with a scope

2: MPLAB StopWatch
You set a breakpoint at the end of the code chunk you want to measure, You set the PC at the start of the code chunk, then you click on Run at PC (refer to MPLAB help file)

3: use a PIC timer
Same concept as StopWatch but you need to send the results to a LCD or via serial communication. The following link explain it better

instruction execution time
http://www.picbasic.co.uk/forum/showthread.php?t=365

i'll try to figure out what the heck happen here... would be nice if i had those shift register

[ADCON]

thanks, I use microcodestudio but this is a reason to look for MPlab.
Microcodestudio sadly don't have a timerfunction. A time ago did I look for MPlab but it looked a lot harder to work with to me.

The shiftregisters works simple. It is data+clock and when all data is loaded a puls so the latches reset to the new value.
Maby you do have Proteus VSM? I mean that they have also this registers(haven't a lisence myself). The datasheet is here: http://www.alldatasheet.com/datashee...S/74HC595.html

The RTC I used is a DS1307 from Maxim-ic.com but that works fine..

[mister_e]

Proteus VSM any sim E+457810214

sorry not for me.

Yeah i know those shift register and i know what a shift register is, what i meant is that it would be great if i had them in stock to build the circuit and test it in a real environment.

I'm not a Sim fan... i know a few people using it for all their design and they seems to be more than happy with it.

[ADCON]

Yes, sim programs are expensive. I had a free beta-testversion once, it had still to much bugs to work with, after that came the pay-version.. I also like to life-test also my bankaccount.. it only takes sometimes some more time. But the good side is that when it workt it really works and with sim-programs is that always a question..

Well, Possibli can you tell me the length of a I2Cread/write procedure because I think that it is also to long. When I start the timer after the ISR it will only read the RTC, it never finishes the coldstart.

I did try to set the prescale to 1:16 but it hadn't any good progress. How do I become a timerinterrupt every 8mSec? of 16msec? Maby I can thy that so it works..

[mister_e]

Well the prescaler was already 1:16 at the first post.. hence why you didn't had any better results
Now what you need to do is to use the POSTscaller. if you set the postscaller to 1:2 you'll have a 2mSec*Prescaller int. 8mSec, postscaller 1:4 and so on

        T2CON = %00011010
                'X------- Unimplemented
                '-0011--- postscale 1:4
                '-----0-- Timer2 off
                '------10 prescaler 1:16

seems to work with the second suggestion

// Snip
        ON INTERRUPT GOTO ISR
        PR2 = 124   ' load period register for 2mSec 
        PEIE = 1    ' Enable peripheral interupt
        GIE = 1     ' enable Global interrupt
        TMR2ON = 1  ' TMR2 ON
        GOTO LOOP                

        disable
ISR:
        TOGGLE PORTB.0
        TMR2IF = 0  ' Clear interrupt flag
        resume
        enable
// end snip

[ADCON]

thanks, i just found it myself.

4000000/4/256/16/2=122
osc/4/8bit/precaler/postprescaler=period
1/122=0,008S

4000000/4/256/16/4=61
1/61=0,016S

now try at the code..

[mister_e]

or... easier way... PICMultiCalc, Timer Helper.
http://www.mister-e.org/pages/utilitiespag.html

255-Value listed in the list, and you're in business

Raise your hand those using it.. at least for timer!!!

OK Darrel