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RE: Problem initialise timer for 1Âµs cycle

by jpdi :: Rate this Message:

Hi,

I find just this morning your problem about Timer.
Because of character problems on the mail I received, I can't see if you
want interrupt each micro-second...
If so, it seems very very fast for that processor.

With 12 Mhz quartz, no PLL, I use an empty function (in C) to delay 2.5
micro-seconds :

void Delay_2_5_micro (void)
{ // nothing to do
}

That means just call and return from this empty function take 2.5
micro-seconds, measured with oscilloscope.

Hope this helps.

Joel

-----Message d'origine-----
De : 68HC12@... [mailto:68HC12@...] De la part de
justin lucas
Envoyé : vendredi 1 mai 2009 18:01
À : 68hc12@...
Objet : RE: [68HC12] Problem initialise timer for 1Âµs cycle

Did you initialize the counter?

I have just implemented a 1 millisecond timer for this processor, but its in
assembly since I use assembly more...

I don't see a initialize routine for a timer starting point...

If you want, I'll pass along my code for the 1 millisecond timer...then you
would have to convert it to the micro second you want..

> To: 68hc12@...
> From: folgli@...
> Date: Fri, 1 May 2009 07:56:39 -0400
> Subject: [68HC12] Problem initialise timer for 1Âµs cycle
>
> Hello,
>
> I have a problem with using the Timer on a MC9S12DP512. I want to create
1Âµ second cycles. Every Âµs I want to increment a variable, but I do not
know how to initialise the timer, so that I get a timer interrupt every Âµs.

> I hope that someone can help me.
> Best regards
>
> Here is my function to initialise the timer:
> --------------------------------------------
>
> void Init_Timers(void)
> {
> TCTL2= 0;
> // TCTL2_OL3= 0;
> /*TCTL2_OM2= 0;
> TCTL2_OL2= 0;
> TCTL2_OM1= 0;
> TCTL2_OL1= 0;
> TCTL2_OM0= 0;
> TCTL2_OL0= 0;*/
>
> TIE&= ~(Bit5|Bit4|Bit3|Bit2|Bit1|Bit0); // C3I= 0, C2I= 0, C1I= 0, C0I= 0
> /*TIE_C2I= 0;
> TIE_C1I= 0;
> TIE_C0I= 0;*/
>
> TTOV&= ~(Bit5|Bit4|Bit3|Bit2|Bit1|Bit0); // TOV3= 0, TOV2= 0, TOV1= 0,

TOV0= 0
> /*TTOV_TOV2= 0;
> TTOV_TOV1= 0;
> TTOV_TOV0= 0;*/
> //TTOV|= Bit6;
>
> TSCR2&= ~(Bit3); // TCRE= 0
>
> TIOS|= Bit5|Bit4|Bit3|Bit2|Bit1|Bit0; // IOS3= 1, IOS2= 1, IOS1= 1, IOS0=
1

> /*TIOS_IOS2= 1;
> TIOS_IOS1= 1;
> TIOS_IOS0= 1;*/
> //TIOS|= Bit6;
>
> TSCR1|= Bit7; // TEN= 1
> TSCR1&= ~(Bit6|Bit5); // TSWAI= 0, TSFRZ= 0
> // TSCR1_TEN= 1;
> // TSCR1_TSWAI= 0;
> // TSCR1_TSFRZ= 0;
>
> PWMCTL&= ~(Bit3|Bit2); // PSWAI= 0, PFRZ= 0
> // PWMCTL_PSWAI= 0;
> // PWMCTL_PFRZ= 0;
> //TCTL2|= Bit4;
> //TC6|= 0x8000;
> PWMSDN= 0;
>
> ICSYS= 0;
>
> //MCCTL|= Bit6; // MODMC= 1
> TSCR2|= 7; // PR2= 1, PR1= 1, PR0= 1
> // TSCR2|= Bit2|Bit1;
> // TSCR2_PR= 6;
> InitTimer1();
> }
>
> and here is my Timer ISR:
> -------------------------
>
> @interrupt void _ISR_Timer1(void)
> {
> ISR_Timer1();
> gTimer1Count++;
> TFLG1= 0b00000010;// C0F - Interrupt Flag: Clear Input Capture 1 Flag
> if( IsTimer1Abgelaufen() )
> {
> StartTimer1(1000);
> }
> }
>
> and here are some other functions I use (used in ISR):
> ------------------------------------------------------
>
> void InitTimer1(void)
> {
> //TC1= TCNT + 65249;
> TIE&= ~Bit1; // C1I= 0
> }
>
> void ISR_Timer1(void)
> {
> TIE&= ~Bit1; // C1I= 0
> bTimer1Abgelaufen= YES;
> TFLG1|= Bit1; // C1F= 1
> }
>
> void StartTimer1(unsigned int ticks)
> {
> TC1= TCNT + ticks; // 65249;
> TFLG1|= Bit1; // C1F= 1
> bTimer1Abgelaufen= NO;
> bTimer1Laeuft= YES;
> TIE|= Bit1; // C1I= 1
> }
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>

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