real time clock

[shahidali55]

Is it possible to use a 32.768 Khz crystal with picbasic pro ?
I know the minimum given in manual is 4 Mhz, but is there anyway to use a 32.768 Khz to reduce power consumption ? ? ?

[skimask]

Is it possible to use a 32.768 Khz crystal with picbasic pro ?
I know the minimum given in manual is 4 Mhz, but is there anyway to use a 32.768 Khz to reduce power consumption ? ? ?

If you run a PIC at 32.768khz, with a PBP program that's compiled to run at 4Mhz, the only thing that'll happen is it'll run 122 times slower (i.e. pause 1 @ 4Mhz = pause 122 @ 32.768khz).

[paul borgmeier]

I know the minimum given in manual is 4 Mhz

Not that helps here, but 3 MHz also is an option as is given in the manual

Define OSC 3

[shahidali55]

I've already tried that skimask. . .
It really puts all the PBP routines off . . .
LCDOUT takes like 3 seconds to print 16 digits . .

[skimask]

It really puts all the PBP routines off . . .
LCDOUT takes like 3 seconds to print 16 digits . .

Which is exactly what I'd expect...unless you write the code in assembly, PBP will time everything like it was running 4Mhz. Maybe try 'lcd_commandus' and lcd_dataus' both set to 1 and see if it works like that at 32khz.

Which PIC are you using this time?
There is a clock switching feature in most newer PICs these days, can switch between the main (4Mhz or whatever) and the internal 32/37/40khz (depends on the datasheet you're looking at) 'backup' oscillator if configured correctly. I use it all the time to save power.

[shahidali55]

I'm using a 16F84A so there is no question of internal oscillator.
I tried several other things besides LCDOUT. Even FOR and WHILE statements take a lot o ftime to execute . . .
I used a external 32.768Khz oscillator.
Just to verify that the F84 was running at 32.768Khz, i tried a clock code on it and it does keep accurate time . . . down to a second a day.

[skimask]

I'm using a 16F84A so there is no question of internal oscillator. I tried several other things besides LCDOUT. Even FOR and WHILE statements take a lot o ftime to execute . . . I used a external 32.768Khz oscillator. Just to verify that the F84 was running at 32.768Khz, i tried a clock code on it and it does keep accurate time . . . down to a second a day.

If you're running 32.768khz, everything is going to take a lot longer to execute.
The clock is 32.768khz, but the PIC is only executing instructions at 8.192khz (Fosc/4), and if you're code has a lot of call's, gosub's, returns, anything that takes the code to 'somewhere else', it'll run half that fast again (4.096khz, Fosc/4 + one extra instruction for each 'somewhere else').

So, what are you asking? What's the point?

[shahidali55]

I think i'll stick to 4Mhz for now . . .