TIM2 FWLIB Example

[frupi]

Posted on November 12, 2009 at 06:15

TIM2 FWLIB Example

[frupi]

Posted on May 17, 2011 at 15:05

Hi to All

Looking in the examples of FWlib from ST in TIM2 PWM frequency Configuration, I don't understand how those numbers come out.I've read the read me file in the folder but seems wrong to me. In particular I would like to produce a square waveform of frequency 125kHz and duty cycle of 50%. I'm using a STM8S103F 20pin QFN package. I was trying to start with the FWLIB from ST with timer2.

Can some one advise me how to?

Thank's for all the support!

Franco

[brazov2]

Posted on May 17, 2011 at 15:05

Also have a look on this document:

discrete.st.com/stonline/products/literature/an/14054.pdf

timers of STM8S103 have more features of the other STM8S family timers, I think that on STM8S103 you have timer5 (see RM) instead of timer2, so timer5 has different register map of timer2.

coluber

[brazov2]

Posted on May 17, 2011 at 15:05

Which compiler and version are you using?

[frupi]

Posted on May 17, 2011 at 15:05

Hi brazov2!

Thank's for the reply. I just want to generate a square wave at 125kHz and duty cycle at 50%. Nothing more. I just want to use The timer2 output compare interrupt but doesn't seem so linear in using it.

Thank's in advace

frupi

[mozra27]

Posted on May 17, 2011 at 15:05

Hi All,

The STM8S103F have 3 timers: TIM1, TIM2 and TIM5

Franco,

Yes, you can do this by using timer2

Example: using the default clock 2MHz and channel1

/* Time base configuration TIM2 Frequency = TIM2 counter clock/(TIM2_ARR + 1) --> TIM2_ARR =(TIM2 counter clock/TIM2 Frequency)-1

=(2000000/125000)-1

=15*/

TIM2_TimeBaseInit(TIM2_PRESCALER_1, 15);

/* TIM2 Channel1 duty cycle = [CCR1_Val/(TIM2_ARR + 1)] * 100 = 50%

--> CCR1_Val = 0.5*(TIM2_ARR + 1)

= 8

*/

/* PWM1 Mode configuration: Channel1 */

CCR1_Val = 8;

TIM2_OC1Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE,CCR1_Val, TIM2_OCPOLARITY_HIGH);

TIM2_OC1PreloadConfig(ENABLE);

TIM2_ARRPreloadConfig(ENABLE);

/* TIM2 enable counter */

TIM2_Cmd(ENABLE);

while(1);

Regards

mozra

[ This message was edited by: mozra27 on 11-11-2009 09:57 ]

[frupi]

Posted on May 17, 2011 at 15:05

Thank's !!!

Another question is: I'm using the internal HSI clock (16Mhz) and fmaster is 16Mhz(prescaler 2^0)is this the clock going in the TIM2 peripheral or not. I don't understand where the 2 Mhz come out, there is no reference in the manual about it.

Ciao

frupi

[frupi]

Posted on May 17, 2011 at 15:05

Hi mozra27

Thank's for the suggestions!!! I will give it a try and come back to you with result. By the way here is the interrupt that I'm using:

void TIM2_CAP_COM_IRQHandler (void)interrupt 14

{

if (TIM2_GetITStatus(TIM2_IT_CC1) != RESET)

{

TIM2_ClearITPendingBit(TIM2_IT_CC1);

capture = TIM2_GetCapture1();

TIM2_SetCompare1( (capture + (UINT16)CCR1_Val) );

}

Can you confirm if this is right!!

Thank's in advance A drink is offered to you!! Cheers!

[brazov2]

Posted on May 17, 2011 at 15:05

Hi Mozra,

are you sure timer2 of stm8s103 is the same of timer2 of stm8s207? If I look at the datasheet of the two products I can see different register mapping. What am I missing?

coluber

[brazov2]

Posted on May 17, 2011 at 15:05

Ops, I made some confusion between devices, I tried mozra suggestion using cosmic compiler and it works fine :)

coluber

[mozra27]

Posted on May 17, 2011 at 15:05

Hi,

Frupi,

The HSI is selected as default clock source;)

Regarding the CLK block diagram: the fHSI is divided by the prescaler that can be configured through HSIDIV[1:0] bits in the CLK_CKDIVR register (the reset value for these bit is 1 so, it divide the fHSI/4 by default) for more details refer to reference manual.

When you use the mode output compare PWM1 you don't need to configure the interrupt.

Coluber,

Yes, the timerx(x=1,2,3,4,5) when available on the product (refer to product datasheet) is the same as the described one in the STM8S microcontroller family reference manual.

Regards

mozra