[OpenRISC] tick timer doubt

[OpenRISC] tick timer doubt

[ecalvo]

Hi!!

 

I have some doubts about the tick timer. Could someone help me? I explain
them below

 

*	I don't understand really well the example of or1k timer control
that is in that file: For example, how is ticks variable updated? 
*	If it was updated, I understand that if frequency is 100Hz, a new
tick takes place each 0.01 seg and with 100 ticks, a second has elapsed.
However, If I compile and run this code and, and I open with gtkwave the
generated vcd, I don't understand why the value of TTMR register is 1000000.
Is The value of TTMR register fixed by software using or1k_timer_set_period
function? Is it measured in Hz?

 

Thanks in advance

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[OpenRISC] tick timer doubt

[Stafford Horne]

Hello,

Which example are you referring to?  Have you been able to read the
architecture specification and understand section 15 on tick timer
facility?  There ttmr is explained, the value 10000000 I think indicates a
pending timer interrupt.

See the attached screenshot.

-stafford

On Fri, Nov 22, 2019, 10:41 PM <ecalvo@2se.es> wrote:

> Hi!!
>
>
>
> I have some doubts about the tick timer. Could someone help me? I explain
> them below
>
>
>
>    - I don’t understand really well the example of or1k timer control
>    that is in that file: For example, how is ticks variable updated?
>    - If it was updated, I understand that if frequency is 100Hz, a new
>    tick takes place each 0.01 seg and with 100 ticks, a second has elapsed.
>    However, If I compile and run this code and, and I open with gtkwave the
>    generated vcd, I don’t understand why the value of TTMR register is
>    1000000. Is The value of TTMR register fixed by software using
>    or1k_timer_set_period function? Is it measured in Hz?
>
>
>
> Thanks in advance
> _______________________________________________
> OpenRISC mailing list
> OpenRISC at lists.librecores.org
> https://lists.librecores.org/listinfo/openrisc
>
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[OpenRISC] tick timer doubt

[ecalvo]

Hello, 

 

 

Yeah, I think that I have understood what you have sent me in the screenshot. 

 

The example that I am referring is this one: 

 

Example for using the default mode:

int main() {

uint32_t ticks = 0;

uint32_t timerstate;

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623> or1k_timer_init(100);

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga369138d63850f2a4dfe216315c31f3d4> or1k_timer_enable();

while (1) {

while (ticks ==  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga2baa18c5153c793b7d2a85c6e224cea0> or1k_timer_get_ticks()) { }

timerstate =  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gab40473a360aa82273575cdbc4381ac93> or1k_timer_disable();

// do something atomar

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga0e392edcf73b9cf1c0279471ae59d241> or1k_timer_restore(timerstate);

if (ticks == 100) {

printf("A second elapsed\n");

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga456bc40cdfbbbdfd62c936c065457cc2> or1k_timer_reset_ticks();

ticks = 0;

}

}

}

It is in the file and also here: https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616

 

Elisa

 

De: Stafford Horne <shorne@gmail.com> 
Enviado el: domingo, 24 de noviembre de 2019 1:05
Para: ecalvo at 2se.es
CC: Openrisc <openrisc@lists.librecores.org>
Asunto: Re: [OpenRISC] tick timer doubt

 

Hello,

 

Which example are you referring to?  Have you been able to read the architecture specification and understand section 15 on tick timer facility?  There ttmr is explained, the value 10000000 I think indicates a pending timer interrupt.

 

See the attached screenshot.

 

-stafford

 

On Fri, Nov 22, 2019, 10:41 PM <ecalvo at 2se.es <mailto:ecalvo@2se.es> > wrote:

Hi!!

 

I have some doubts about the tick timer. Could someone help me? I explain them below

 

*	I don’t understand really well the example of or1k timer control that is in that file: For example, how is ticks variable updated? 
*	If it was updated, I understand that if frequency is 100Hz, a new tick takes place each 0.01 seg and with 100 ticks, a second has elapsed. However, If I compile and run this code and, and I open with gtkwave the generated vcd, I don’t understand why the value of TTMR register is 1000000. Is The value of TTMR register fixed by software using or1k_timer_set_period function? Is it measured in Hz?

 

Thanks in advance

_______________________________________________
OpenRISC mailing list
OpenRISC at lists.librecores.org <mailto:OpenRISC@lists.librecores.org> 
https://lists.librecores.org/listinfo/openrisc

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[OpenRISC] tick timer doubt

[Stafford Horne]

Good point,

I think it's missing a line to update the ticks variable.

I terms of ttmr I am not sure if there is anything won't there.  I'll try
to run it and fix it when I get a chance.

On Mon, Nov 25, 2019, 5:20 PM <ecalvo@2se.es> wrote:

> Hello,
>
>
>
>
>
> Yeah, I think that I have understood what you have sent me in the
> screenshot.
>
>
>
> The example that I am referring is this one:
>
>
>
> Example for using the default mode:
>
> int main() {
>
> uint32_t ticks = 0;
>
> uint32_t timerstate;
>
> or1k_timer_init
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623>
> (100);
>
> or1k_timer_enable
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga369138d63850f2a4dfe216315c31f3d4>
> ();
>
> while (1) {
>
> while (ticks == or1k_timer_get_ticks
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga2baa18c5153c793b7d2a85c6e224cea0>())
> { }
>
> timerstate = or1k_timer_disable
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gab40473a360aa82273575cdbc4381ac93>
> ();
>
> // do something atomar
>
> or1k_timer_restore
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga0e392edcf73b9cf1c0279471ae59d241>
> (timerstate);
>
> if (ticks == 100) {
>
> printf("A second elapsed\n");
>
> or1k_timer_reset_ticks
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga456bc40cdfbbbdfd62c936c065457cc2>
> ();
>
> ticks = 0;
>
> }
>
> }
>
> }
>
> It is in the file and also here:
> https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616
>
>
>
> Elisa
>
>
>
> *De:* Stafford Horne <shorne@gmail.com>
> *Enviado el:* domingo, 24 de noviembre de 2019 1:05
> *Para:* ecalvo at 2se.es
> *CC:* Openrisc <openrisc@lists.librecores.org>
> *Asunto:* Re: [OpenRISC] tick timer doubt
>
>
>
> Hello,
>
>
>
> Which example are you referring to?  Have you been able to read the
> architecture specification and understand section 15 on tick timer
> facility?  There ttmr is explained, the value 10000000 I think indicates a
> pending timer interrupt.
>
>
>
> See the attached screenshot.
>
>
>
> -stafford
>
>
>
> On Fri, Nov 22, 2019, 10:41 PM <ecalvo@2se.es> wrote:
>
> Hi!!
>
>
>
> I have some doubts about the tick timer. Could someone help me? I explain
> them below
>
>
>
>    - I don’t understand really well the example of or1k timer control
>    that is in that file: For example, how is ticks variable updated?
>    - If it was updated, I understand that if frequency is 100Hz, a new
>    tick takes place each 0.01 seg and with 100 ticks, a second has elapsed.
>    However, If I compile and run this code and, and I open with gtkwave the
>    generated vcd, I don’t understand why the value of TTMR register is
>    1000000. Is The value of TTMR register fixed by software using
>    or1k_timer_set_period function? Is it measured in Hz?
>
>
>
> Thanks in advance
>
> _______________________________________________
> OpenRISC mailing list
> OpenRISC at lists.librecores.org
> https://lists.librecores.org/listinfo/openrisc
>
>
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[OpenRISC] tick timer doubt

[ecalvo]

Okk, but, independently of the ticks variable updating,  ttmr register… should it have the value that has been configured with  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623> or1k_timer_init?

 

 

De: Stafford Horne <shorne@gmail.com> 
Enviado el: lunes, 25 de noviembre de 2019 10:22
Para: ecalvo at 2se.es
CC: Openrisc <openrisc@lists.librecores.org>
Asunto: Re: [OpenRISC] tick timer doubt

 

Good point,

 

I think it's missing a line to update the ticks variable.

 

I terms of ttmr I am not sure if there is anything won't there.  I'll try to run it and fix it when I get a chance.

 

On Mon, Nov 25, 2019, 5:20 PM < <mailto:ecalvo@2se.es> ecalvo at 2se.es> wrote:

Hello, 

 

 

Yeah, I think that I have understood what you have sent me in the screenshot. 

 

The example that I am referring is this one: 

 

Example for using the default mode:

int main() {

uint32_t ticks = 0;

uint32_t timerstate;

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623> or1k_timer_init(100);

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga369138d63850f2a4dfe216315c31f3d4> or1k_timer_enable();

while (1) {

while (ticks ==  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga2baa18c5153c793b7d2a85c6e224cea0> or1k_timer_get_ticks()) { }

timerstate =  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gab40473a360aa82273575cdbc4381ac93> or1k_timer_disable();

// do something atomar

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga0e392edcf73b9cf1c0279471ae59d241> or1k_timer_restore(timerstate);

if (ticks == 100) {

printf("A second elapsed\n");

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga456bc40cdfbbbdfd62c936c065457cc2> or1k_timer_reset_ticks();

ticks = 0;

}

}

}

It is in the file and also here:  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616> https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616

 

Elisa

 

De: Stafford Horne <shorne at gmail.com <mailto:shorne@gmail.com> > 
Enviado el: domingo, 24 de noviembre de 2019 1:05
Para: ecalvo at 2se.es <mailto:ecalvo@2se.es> 
CC: Openrisc <openrisc at lists.librecores.org <mailto:openrisc@lists.librecores.org> >
Asunto: Re: [OpenRISC] tick timer doubt

 

Hello,

 

Which example are you referring to?  Have you been able to read the architecture specification and understand section 15 on tick timer facility?  There ttmr is explained, the value 10000000 I think indicates a pending timer interrupt.

 

See the attached screenshot.

 

-stafford

 

On Fri, Nov 22, 2019, 10:41 PM < <mailto:ecalvo@2se.es> ecalvo at 2se.es> wrote:

Hi!!

 

I have some doubts about the tick timer. Could someone help me? I explain them below

 

*	I don’t understand really well the example of or1k timer control that is in that file: For example, how is ticks variable updated? 
*	If it was updated, I understand that if frequency is 100Hz, a new tick takes place each 0.01 seg and with 100 ticks, a second has elapsed. However, If I compile and run this code and, and I open with gtkwave the generated vcd, I don’t understand why the value of TTMR register is 1000000. Is The value of TTMR register fixed by software using or1k_timer_set_period function? Is it measured in Hz?

 

Thanks in advance

_______________________________________________
OpenRISC mailing list
 <mailto:OpenRISC@lists.librecores.org> OpenRISC at lists.librecores.org
 <https://lists.librecores.org/listinfo/openrisc> https://lists.librecores.org/listinfo/openrisc

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[OpenRISC] tick timer doubt

[Stafford Horne]

Hello,

Yes ttmr will be updated with the value set in or1k_timer_init().  Seem my
test below it seems to work fine on mor1kx and marocchino for me.

I tested this out and it seems to work fine:

#include <or1k-support.h>
#include <stdio.h>

#define TICK_HZ 10000

int main() {
   uint32_t ticks = 0;
   uint32_t timerstate;
   or1k_timer_init(TICK_HZ);
   or1k_timer_enable();

   printf("starting timer\n");

   while (1) {
     while (ticks == or1k_timer_get_ticks()) {
       /* Wait for timer to change */
     }

     timerstate = or1k_timer_disable();
     /* disable timer interrupts, do something atomic */
     or1k_timer_restore(timerstate);

     printf("Timer is %ld\n", ticks);

     if (ticks == TICK_HZ) {
       printf("A second elapsed\n");
       or1k_timer_reset_ticks();
       ticks = 0;
    } else {
       ticks = or1k_timer_get_ticks();
    }
  }
}

Note, I added the line to update the ticks value, to get the ticks to
actually update and I updated some comments.

If I run this program it seems to count correctly.  If I simulate it with
100Hz it takes too long to actually count.

elf-loader: /home/shorne/work/openrisc/a.out was loaded
Loading       21481 words
                   0 : Illegal Wishbone B3 cycle type (xxx)
starting timer
Timer is 0
Timer is 1
...

See the VCD with 10_000 hz.


*Enabling the Timer*
TTMR has 0x2710, it should be 100,000,000 / 10,000, which is 10,000 0x2710.

The TTCR starts to count up after enabled.

[image: Screenshot from 2019-11-25 21-42-36.png]


*Timer Ticks 1 time*

We can see the interrupt bit of TTMR goes high and the timer exception is
raised and handled with the TTMR matches the TTCR.
[image: Screenshot from 2019-11-25 21-45-56.png]


On Mon, Nov 25, 2019 at 7:09 PM <ecalvo@2se.es> wrote:

> Okk, but, independently of the ticks variable updating,  ttmr register…
> should it have the value that has been configured with or1k_timer_init
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623>
> ?
>
>
>
>
>
> *De:* Stafford Horne <shorne@gmail.com>
> *Enviado el:* lunes, 25 de noviembre de 2019 10:22
> *Para:* ecalvo at 2se.es
> *CC:* Openrisc <openrisc@lists.librecores.org>
> *Asunto:* Re: [OpenRISC] tick timer doubt
>
>
>
> Good point,
>
>
>
> I think it's missing a line to update the ticks variable.
>
>
>
> I terms of ttmr I am not sure if there is anything won't there.  I'll try
> to run it and fix it when I get a chance.
>
>
>
> On Mon, Nov 25, 2019, 5:20 PM <ecalvo@2se.es> wrote:
>
> Hello,
>
>
>
>
>
> Yeah, I think that I have understood what you have sent me in the
> screenshot.
>
>
>
> The example that I am referring is this one:
>
>
>
> Example for using the default mode:
>
> int main() {
>
> uint32_t ticks = 0;
>
> uint32_t timerstate;
>
> or1k_timer_init
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623>
> (100);
>
> or1k_timer_enable
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga369138d63850f2a4dfe216315c31f3d4>
> ();
>
> while (1) {
>
> while (ticks == or1k_timer_get_ticks
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga2baa18c5153c793b7d2a85c6e224cea0>())
> { }
>
> timerstate = or1k_timer_disable
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gab40473a360aa82273575cdbc4381ac93>
> ();
>
> // do something atomar
>
> or1k_timer_restore
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga0e392edcf73b9cf1c0279471ae59d241>
> (timerstate);
>
> if (ticks == 100) {
>
> printf("A second elapsed\n");
>
> or1k_timer_reset_ticks
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga456bc40cdfbbbdfd62c936c065457cc2>
> ();
>
> ticks = 0;
>
> }
>
> }
>
> }
>
> It is in the file and also here:
> https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616
>
>
>
> Elisa
>
>
>
> *De:* Stafford Horne <shorne@gmail.com>
> *Enviado el:* domingo, 24 de noviembre de 2019 1:05
> *Para:* ecalvo at 2se.es
> *CC:* Openrisc <openrisc@lists.librecores.org>
> *Asunto:* Re: [OpenRISC] tick timer doubt
>
>
>
> Hello,
>
>
>
> Which example are you referring to?  Have you been able to read the
> architecture specification and understand section 15 on tick timer
> facility?  There ttmr is explained, the value 10000000 I think indicates a
> pending timer interrupt.
>
>
>
> See the attached screenshot.
>
>
>
> -stafford
>
>
>
> On Fri, Nov 22, 2019, 10:41 PM <ecalvo@2se.es> wrote:
>
> Hi!!
>
>
>
> I have some doubts about the tick timer. Could someone help me? I explain
> them below
>
>
>
>    - I don’t understand really well the example of or1k timer control
>    that is in that file: For example, how is ticks variable updated?
>    - If it was updated, I understand that if frequency is 100Hz, a new
>    tick takes place each 0.01 seg and with 100 ticks, a second has elapsed.
>    However, If I compile and run this code and, and I open with gtkwave the
>    generated vcd, I don’t understand why the value of TTMR register is
>    1000000. Is The value of TTMR register fixed by software using
>    or1k_timer_set_period function? Is it measured in Hz?
>
>
>
> Thanks in advance
>
> _______________________________________________
> OpenRISC mailing list
> OpenRISC at lists.librecores.org
> https://lists.librecores.org/listinfo/openrisc
>
>
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[OpenRISC] tick timer doubt

[ecalvo]

Thanks for the example. It is really useful for me. 

 

1.	Okkk to the update of ticks variable. 
2.	When you disable timer interrupts, I have read (also here: https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616) that timer counting doesn’t stop. But when I execute it, with a loop in that position, I don’t get difference in ticks before and later….

 

About the question with ork_timer_init and ttmr…

1.	What does “TTMR has 0x2710, it should be 100,000,000 / 10,000, which is 10,000 0x2710.” Mean? (red part). when I open gtkwave ttmr register does not have the same value.If I set with ork_timer_init function 100, ttmr counts up to 1000000, whereas if I set 1000, it counts up to 100000. 
2.	In page 333 of the architecture specification, Figure 15,1, I understand that you fix a value that compares with the output of a counter. If they are equals, the output is the interruption. But I understand that this is dependent on the clock frequency of RISC. How I can fix from software with  or1k_timer_init the frequency? I don’t know if I am explaining myself….

 

Thanks again

 

De: Stafford Horne <shorne@gmail.com> 
Enviado el: lunes, 25 de noviembre de 2019 14:04
Para: ecalvo at 2se.es
CC: Openrisc <openrisc@lists.librecores.org>
Asunto: Re: [OpenRISC] tick timer doubt

 

Hello,

 

Yes ttmr will be updated with the value set in or1k_timer_init().  Seem my test below it seems to work fine on mor1kx and marocchino for me.

 

I tested this out and it seems to work fine:

 

#include <or1k-support.h>
#include <stdio.h>

#define TICK_HZ 10000

int main() {
   uint32_t ticks = 0;
   uint32_t timerstate;
   or1k_timer_init(TICK_HZ);
   or1k_timer_enable();

   printf("starting timer\n");

   while (1) {
     while (ticks == or1k_timer_get_ticks()) { 
       /* Wait for timer to change */ 
     }

     timerstate = or1k_timer_disable();
     /* disable timer interrupts, do something atomic */
     or1k_timer_restore(timerstate);

     printf("Timer is %ld\n", ticks);

     if (ticks == TICK_HZ) {
       printf("A second elapsed\n");
       or1k_timer_reset_ticks();
       ticks = 0;
    } else {
       ticks = or1k_timer_get_ticks();
    }
  }
}

 

Note, I added the line to update the ticks value, to get the ticks to actually update and I updated some comments.

 

If I run this program it seems to count correctly.  If I simulate it with 100Hz it takes too long to actually count.

 

elf-loader: /home/shorne/work/openrisc/a.out was loaded
Loading       21481 words
                   0 : Illegal Wishbone B3 cycle type (xxx)
starting timer
Timer is 0
Timer is 1

...

 

See the VCD with 10_000 hz.

 

 

Enabling the Timer

TTMR has 0x2710, it should be 100,000,000 / 10,000, which is 10,000 0x2710.

 

The TTCR starts to count up after enabled.

 



 

 

Timer Ticks 1 time

 

We can see the interrupt bit of TTMR goes high and the timer exception is raised and handled with the TTMR matches the TTCR. 



 

 

On Mon, Nov 25, 2019 at 7:09 PM <ecalvo at 2se.es <mailto:ecalvo@2se.es> > wrote:

Okk, but, independently of the ticks variable updating,  ttmr register… should it have the value that has been configured with  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623> or1k_timer_init?

 

 

De: Stafford Horne <shorne at gmail.com <mailto:shorne@gmail.com> > 
Enviado el: lunes, 25 de noviembre de 2019 10:22
Para: ecalvo at 2se.es <mailto:ecalvo@2se.es> 
CC: Openrisc <openrisc at lists.librecores.org <mailto:openrisc@lists.librecores.org> >
Asunto: Re: [OpenRISC] tick timer doubt

 

Good point,

 

I think it's missing a line to update the ticks variable.

 

I terms of ttmr I am not sure if there is anything won't there.  I'll try to run it and fix it when I get a chance.

 

On Mon, Nov 25, 2019, 5:20 PM < <mailto:ecalvo@2se.es> ecalvo at 2se.es> wrote:

Hello, 

 

 

Yeah, I think that I have understood what you have sent me in the screenshot. 

 

The example that I am referring is this one: 

 

Example for using the default mode:

int main() {

uint32_t ticks = 0;

uint32_t timerstate;

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623> or1k_timer_init(100);

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga369138d63850f2a4dfe216315c31f3d4> or1k_timer_enable();

while (1) {

while (ticks ==  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga2baa18c5153c793b7d2a85c6e224cea0> or1k_timer_get_ticks()) { }

timerstate =  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gab40473a360aa82273575cdbc4381ac93> or1k_timer_disable();

// do something atomar

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga0e392edcf73b9cf1c0279471ae59d241> or1k_timer_restore(timerstate);

if (ticks == 100) {

printf("A second elapsed\n");

 <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga456bc40cdfbbbdfd62c936c065457cc2> or1k_timer_reset_ticks();

ticks = 0;

}

}

}

It is in the file and also here:  <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616> https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616

 

Elisa

 

De: Stafford Horne <shorne at gmail.com <mailto:shorne@gmail.com> > 
Enviado el: domingo, 24 de noviembre de 2019 1:05
Para: ecalvo at 2se.es <mailto:ecalvo@2se.es> 
CC: Openrisc <openrisc at lists.librecores.org <mailto:openrisc@lists.librecores.org> >
Asunto: Re: [OpenRISC] tick timer doubt

 

Hello,

 

Which example are you referring to?  Have you been able to read the architecture specification and understand section 15 on tick timer facility?  There ttmr is explained, the value 10000000 I think indicates a pending timer interrupt.

 

See the attached screenshot.

 

-stafford

 

On Fri, Nov 22, 2019, 10:41 PM < <mailto:ecalvo@2se.es> ecalvo at 2se.es> wrote:

Hi!!

 

I have some doubts about the tick timer. Could someone help me? I explain them below

 

*	I don’t understand really well the example of or1k timer control that is in that file: For example, how is ticks variable updated? 
*	If it was updated, I understand that if frequency is 100Hz, a new tick takes place each 0.01 seg and with 100 ticks, a second has elapsed. However, If I compile and run this code and, and I open with gtkwave the generated vcd, I don’t understand why the value of TTMR register is 1000000. Is The value of TTMR register fixed by software using or1k_timer_set_period function? Is it measured in Hz?

 

Thanks in advance

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[OpenRISC] tick timer doubt

[Stafford Horne]

Hello,

Can you send a picture or output showing ttmr counting?   It should not
count ttcr counts.

Some points.

1. The function of or1k_timer_init is to set up ttmr counter mask bits.
The default board selected by newlib or1ksim has a frequency of
100,000,000.  You can change that with -mboard=... See:
https://gcc.gnu.org/onlinedocs/gcc-9.2.0/gcc/OpenRISC-Options.html

2. The mask value placed in ttmr will be board-frequency divided by
requested-frequency.

3. The or1k_timer_enable() call will enable timer interrupts updating the
ttmr register again.

4. An interrupt handler is setup to be called at that frequency and update
an internal ticks variable every time it's called.

5. The internal ticks variable can be read with or1k_timer_get_ticks().
That value will change at the frequency set in step 1.


Counting does not stop when interrupts are disabled.  This allows to
maintain stable timer event frequency.

On Mon, Nov 25, 2019, 10:24 PM <ecalvo@2se.es> wrote:

> Thanks for the example. It is really useful for me.
>
>
>
>    1. Okkk to the update of ticks variable.
>    2. When you disable timer interrupts, I have read (also here:
>    https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616)
>    that timer counting doesn’t stop. But when I execute it, with a loop in
>    that position, I don’t get difference in ticks before and later….
>
>
>
> About the question with ork_timer_init and ttmr…
>
>    1. What does “TTMR has 0x2710, it should be 100,000,000 / 10,000,
>    which is 10,000 0x2710.” Mean? (red part). when I open gtkwave ttmr
>    register does not have the same value.If I set with ork_timer_init function
>    100, ttmr counts up to 1000000, whereas if I set 1000, it counts up to
>    100000.
>    2. In page 333 of the architecture specification, Figure 15,1, I
>    understand that you fix a value that compares with the output of a counter.
>    If they are equals, the output is the interruption. But I understand that
>    this is dependent on the clock frequency of RISC. How I can fix from
>    software with  or1k_timer_init the frequency? I don’t know if I am
>    explaining myself….
>
>
>
> Thanks again
>
>
>
> *De:* Stafford Horne <shorne@gmail.com>
> *Enviado el:* lunes, 25 de noviembre de 2019 14:04
> *Para:* ecalvo at 2se.es
> *CC:* Openrisc <openrisc@lists.librecores.org>
> *Asunto:* Re: [OpenRISC] tick timer doubt
>
>
>
> Hello,
>
>
>
> Yes ttmr will be updated with the value set in or1k_timer_init().  Seem my
> test below it seems to work fine on mor1kx and marocchino for me.
>
>
>
> I tested this out and it seems to work fine:
>
>
>
> #include <or1k-support.h>
> #include <stdio.h>
>
> #define TICK_HZ 10000
>
> int main() {
>    uint32_t ticks = 0;
>    uint32_t timerstate;
>    or1k_timer_init(TICK_HZ);
>    or1k_timer_enable();
>
>    printf("starting timer\n");
>
>    while (1) {
>      while (ticks == or1k_timer_get_ticks()) {
>        /* Wait for timer to change */
>      }
>
>      timerstate = or1k_timer_disable();
>      /* disable timer interrupts, do something atomic */
>      or1k_timer_restore(timerstate);
>
>      printf("Timer is %ld\n", ticks);
>
>      if (ticks == TICK_HZ) {
>        printf("A second elapsed\n");
>        or1k_timer_reset_ticks();
>        ticks = 0;
>     } else {
>        ticks = or1k_timer_get_ticks();
>     }
>   }
> }
>
>
>
> Note, I added the line to update the ticks value, to get the ticks to
> actually update and I updated some comments.
>
>
>
> If I run this program it seems to count correctly.  If I simulate it with
> 100Hz it takes too long to actually count.
>
>
>
> elf-loader: /home/shorne/work/openrisc/a.out was loaded
> Loading       21481 words
>                    0 : Illegal Wishbone B3 cycle type (xxx)
> starting timer
> Timer is 0
> Timer is 1
>
> ...
>
>
>
> See the VCD with 10_000 hz.
>
>
>
>
>
> *Enabling the Timer*
>
> TTMR has 0x2710, it should be 100,000,000 / 10,000, which is 10,000 0x2710.
>
>
>
> The TTCR starts to count up after enabled.
>
>
>
> [image: Screenshot from 2019-11-25 21-42-36.png]
>
>
>
>
>
> *Timer Ticks 1 time*
>
>
>
> We can see the interrupt bit of TTMR goes high and the timer exception is
> raised and handled with the TTMR matches the TTCR.
>
> [image: Screenshot from 2019-11-25 21-45-56.png]
>
>
>
>
>
> On Mon, Nov 25, 2019 at 7:09 PM <ecalvo@2se.es> wrote:
>
> Okk, but, independently of the ticks variable updating,  ttmr register…
> should it have the value that has been configured with or1k_timer_init
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623>
> ?
>
>
>
>
>
> *De:* Stafford Horne <shorne@gmail.com>
> *Enviado el:* lunes, 25 de noviembre de 2019 10:22
> *Para:* ecalvo at 2se.es
> *CC:* Openrisc <openrisc@lists.librecores.org>
> *Asunto:* Re: [OpenRISC] tick timer doubt
>
>
>
> Good point,
>
>
>
> I think it's missing a line to update the ticks variable.
>
>
>
> I terms of ttmr I am not sure if there is anything won't there.  I'll try
> to run it and fix it when I get a chance.
>
>
>
> On Mon, Nov 25, 2019, 5:20 PM <ecalvo@2se.es> wrote:
>
> Hello,
>
>
>
>
>
> Yeah, I think that I have understood what you have sent me in the
> screenshot.
>
>
>
> The example that I am referring is this one:
>
>
>
> Example for using the default mode:
>
> int main() {
>
> uint32_t ticks = 0;
>
> uint32_t timerstate;
>
> or1k_timer_init
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga432f34016f4f559c29b0be4fbc87e623>
> (100);
>
> or1k_timer_enable
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga369138d63850f2a4dfe216315c31f3d4>
> ();
>
> while (1) {
>
> while (ticks == or1k_timer_get_ticks
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga2baa18c5153c793b7d2a85c6e224cea0>())
> { }
>
> timerstate = or1k_timer_disable
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gab40473a360aa82273575cdbc4381ac93>
> ();
>
> // do something atomar
>
> or1k_timer_restore
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga0e392edcf73b9cf1c0279471ae59d241>
> (timerstate);
>
> if (ticks == 100) {
>
> printf("A second elapsed\n");
>
> or1k_timer_reset_ticks
> <https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#ga456bc40cdfbbbdfd62c936c065457cc2>
> ();
>
> ticks = 0;
>
> }
>
> }
>
> }
>
> It is in the file and also here:
> https://www.openrisc.io/newlib/docs/html/group__or1k__timer.html#gaf760867d2f9d04f0c101c4c4975b0616
>
>
>
> Elisa
>
>
>
> *De:* Stafford Horne <shorne@gmail.com>
> *Enviado el:* domingo, 24 de noviembre de 2019 1:05
> *Para:* ecalvo at 2se.es
> *CC:* Openrisc <openrisc@lists.librecores.org>
> *Asunto:* Re: [OpenRISC] tick timer doubt
>
>
>
> Hello,
>
>
>
> Which example are you referring to?  Have you been able to read the
> architecture specification and understand section 15 on tick timer
> facility?  There ttmr is explained, the value 10000000 I think indicates a
> pending timer interrupt.
>
>
>
> See the attached screenshot.
>
>
>
> -stafford
>
>
>
> On Fri, Nov 22, 2019, 10:41 PM <ecalvo@2se.es> wrote:
>
> Hi!!
>
>
>
> I have some doubts about the tick timer. Could someone help me? I explain
> them below
>
>
>
>    - I don’t understand really well the example of or1k timer control
>    that is in that file: For example, how is ticks variable updated?
>    - If it was updated, I understand that if frequency is 100Hz, a new
>    tick takes place each 0.01 seg and with 100 ticks, a second has elapsed.
>    However, If I compile and run this code and, and I open with gtkwave the
>    generated vcd, I don’t understand why the value of TTMR register is
>    1000000. Is The value of TTMR register fixed by software using
>    or1k_timer_set_period function? Is it measured in Hz?
>
>
>
> Thanks in advance
>
> _______________________________________________
> OpenRISC mailing list
> OpenRISC at lists.librecores.org
> https://lists.librecores.org/listinfo/openrisc
>
>
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