multiply oscillators

[ozzieB]

Hi,

I want to use 4 osscilators @ 1 pic..
So I can choose between different oscillatos, (8,12,16,20 MhZ)..


@ DEVICE PIC16F628A, MCLR_OFF 'MCLR PIN IS DIGITAL
@ DEVICE PIC16F628A, WDT_OFF 'WATCHDOG TIMER OFF
@ DEVICE PIC16F628A, INTOSC_OSC_NOCLKOUT 'Internal (INTOSC) oscillator with clock Output

TRISA = %00000001 '0 = OUTPUT, 1 = INPUT
TRISB = %00000000 '0 = OUTPUT, 1 = INPUT

CMCON = %00000111 'COMPARATORS OFF

S0 VAR PORTB.0
LED VAR PORTB.2
TESTJE VAR PORTB.1

PORTA=0
PORTB=0

Clear 'ALL BUFFERS 0

TEST:
@ DEVICE PIC16F628A, HS_OSC 'HIGH SPEED OSC
LED = 1
DEFINE OSC 16
TESTJE = 1
Pause 1000
TESTJE = 0
LED = 0
DEFINE OSC 20
TESTJE = 1
Pause 1000
TESTJE = 0

GoTo TEST


this is my code so far, but i dont work... any ideas of how to do this?

[Acetronics2]

Hi,

Define is only used at compile time to tell the compiler which formula to use to get the right timings ...

so, what you intend to do hasn't the least chance to work ... what you can do is add a freq variable :


[code]

SELECT CASE Freq

Case 16

TESTJE = 1
Pause 4*1000
TESTJE = 0
LED = 0

Case 20
TESTJE = 1
Pause 5*1000
TESTJE = 0

END SELECT

But will only EASILY work for simple commands ... ( Not with One Wire, Serial or HPWM ..)

Now ... surely Darrel has a library "hacking" for that ... at asm level !

Alain

[ozzieB]

Hi,

Define is only used at compile time to tell the compiler which formula to use to get the right timings ...

so, what you intend to do hasn't the least chance to work ... what you can do is add a freq variable :


[code]

SELECT CASE Freq

Case 16

TESTJE = 1
Pause 4*1000
TESTJE = 0
LED = 0

Case 20
TESTJE = 1
Pause 5*1000
TESTJE = 0

END SELECT

But will only EASILY work for simple commands ... ( Not with One Wire, Serial or HPWM ..)

Now ... surely Darrel has a library "hacking" for that ... at asm level !

Alain

I need it for hpwm.. :(

[Acetronics2]

So, Consider

if You set HPWM @ 1000 Hz for a default 4Mhz Clock ...

HPWM will run @ 4000 Hz for Xtal @ 16 Mhz

.................. @ 5000 Hz for Xtal @ 20 Mhz


Just correct your HPWM frequencies like that ...

You also can have a look to Genuine examples that show how to use the PWM modules without using the HPWM command ...

Alain

[Charles Linquis]

You can actually change the PLL and divider at run time. Probably the best way is to use Darrel Taylor's WriteConfig utility.

[mister_e]

Problem is that it is only valid on 18F.

Is there any specific reason why you want to use multiple OSC speed at runtime?

[Charles Linquis]

There are so many reasons not to use 16F parts. This is just one more.

[ozzieB]

Problem is that it is only valid on 18F.

Is there any specific reason why you want to use multiple OSC speed at runtime?

i need it to take dutcycle steps by 0,1% and not 0,3%..

[Acetronics2]

i need it to take dutcycle steps by 0,1% and not 0,3%..

Hi, Ozzie

I saw on this forum one of Darrel's Goodies called " HPWM 10 " ...

as it means ...

Alain