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Discussion Groups | 68HC12 | Getting the Pulse Accumulator working
Join our technical discussions about Freescale Microcontrollers: M68HC12. (Freescale Semiconductor is a Subsidiary of Motorola).
Getting the Pulse Accumulator working - adlai15 - Aug 23 14:49:00 2005
Hi,
I would like to have my timers(Ch. 4 -7) interrupt me after a number
of seconds have passed. It seems that the only way to do this is to
use the Pulse Accumulator's clock PACLK and divide it by 65536 using
the CLK1:0 bits in the PACTL.
Currently I have IOC7 through IOC4 tied to GND, and am setting PACTL
to 0x7C. But my channel 4 timer isn't getting interrupts. Only when I
disable the Pulse Accumulator does the channel 4 timer interrupt.
Can someone make a suggestion as to how to make this work? Or if there
is another way to make the counters count for several seconds I would
be interested in that too.
Thanks,
Adlai
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
I would like to have my timers(Ch. 4 -7) interrupt me after a number
of seconds have passed. It seems that the only way to do this is to
use the Pulse Accumulator's clock PACLK and divide it by 65536 using
the CLK1:0 bits in the PACTL.
Currently I have IOC7 through IOC4 tied to GND, and am setting PACTL
to 0x7C. But my channel 4 timer isn't getting interrupts. Only when I
disable the Pulse Accumulator does the channel 4 timer interrupt.
Can someone make a suggestion as to how to make this work? Or if there
is another way to make the counters count for several seconds I would
be interested in that too.
Thanks,
Adlai
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
RE: Getting the Pulse Accumulator working - Redd, Emmett R - Aug 23 16:29:00 2005
To only count time, you do not have to (and probably should not) use the
Pulse Accumulator. All you need to do is keep track of the number of
times a timer overflows or times out. Attached are two files showing
how the 68HC11 timer (very much like the HC12) making 1 second ticks. I
think it could easily be extended to a 9-second period by only changing
the 3-byte number representing the timer tics in a period. Beyond that
one would have to slow down the timer tics or extend the 3-byte number.
Another example make long periods is in Han-Way Huang's 68HC12 book on
page 307-9. His Example 8.5 has both assembly and C code.
Emmett Redd Ph.D. mailto:EmmettRedd@Emme...
Associate Professor (417)836-5221
Department of Physics, Astronomy, and Materials Science
Southwest Missouri State University Fax (417)836-6226
901 SOUTH NATIONAL Dept (417)836-5131
SPRINGFIELD, MO 65804 USA
> -----Original Message-----
> From: 68HC12@68HC... [mailto:68HC12@68HC...]
> On Behalf Of adlai15
> Sent: Tuesday, August 23, 2005 1:49 PM
> To: 68HC12@68HC...
> Subject: [68HC12] Getting the Pulse Accumulator working
>
> Hi,
>
> I would like to have my timers(Ch. 4 -7) interrupt me after a number
> of seconds have passed. It seems that the only way to do this is to
> use the Pulse Accumulator's clock PACLK and divide it by 65536 using
> the CLK1:0 bits in the PACTL.
>
> Currently I have IOC7 through IOC4 tied to GND, and am setting PACTL
> to 0x7C. But my channel 4 timer isn't getting interrupts. Only when I
> disable the Pulse Accumulator does the channel 4 timer interrupt.
>
> Can someone make a suggestion as to how to make this work? Or
> if there
> is another way to make the counters count for several seconds I would
> be interested in that too.
>
> Thanks,
> Adlai [Non-text portions of this message have been removed]
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
Pulse Accumulator. All you need to do is keep track of the number of
times a timer overflows or times out. Attached are two files showing
how the 68HC11 timer (very much like the HC12) making 1 second ticks. I
think it could easily be extended to a 9-second period by only changing
the 3-byte number representing the timer tics in a period. Beyond that
one would have to slow down the timer tics or extend the 3-byte number.
Another example make long periods is in Han-Way Huang's 68HC12 book on
page 307-9. His Example 8.5 has both assembly and C code.
Emmett Redd Ph.D. mailto:EmmettRedd@Emme...
Associate Professor (417)836-5221
Department of Physics, Astronomy, and Materials Science
Southwest Missouri State University Fax (417)836-6226
901 SOUTH NATIONAL Dept (417)836-5131
SPRINGFIELD, MO 65804 USA
> -----Original Message-----
> From: 68HC12@68HC... [mailto:68HC12@68HC...]
> On Behalf Of adlai15
> Sent: Tuesday, August 23, 2005 1:49 PM
> To: 68HC12@68HC...
> Subject: [68HC12] Getting the Pulse Accumulator working
>
> Hi,
>
> I would like to have my timers(Ch. 4 -7) interrupt me after a number
> of seconds have passed. It seems that the only way to do this is to
> use the Pulse Accumulator's clock PACLK and divide it by 65536 using
> the CLK1:0 bits in the PACTL.
>
> Currently I have IOC7 through IOC4 tied to GND, and am setting PACTL
> to 0x7C. But my channel 4 timer isn't getting interrupts. Only when I
> disable the Pulse Accumulator does the channel 4 timer interrupt.
>
> Can someone make a suggestion as to how to make this work? Or
> if there
> is another way to make the counters count for several seconds I would
> be interested in that too.
>
> Thanks,
> Adlai [Non-text portions of this message have been removed]
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
Re: Getting the Pulse Accumulator working - Dave Perreault - Aug 23 17:41:00 2005
The usual way of doing this is to set the hardware timer for as large a
time as possible depending on your clock. Then in the interrupt routine
establish a sotware down counter to get to your overall large time. When
the SW counts down to 0, reset the down counter and do your thing.
Dave Dave adlai15 wrote:
> Hi,
>
> I would like to have my timers(Ch. 4 -7) interrupt me after a number
> of seconds have passed. It seems that the only way to do this is to
> use the Pulse Accumulator's clock PACLK and divide it by 65536 using
> the CLK1:0 bits in the PACTL.
>
> Currently I have IOC7 through IOC4 tied to GND, and am setting PACTL
> to 0x7C. But my channel 4 timer isn't getting interrupts. Only when I
> disable the Pulse Accumulator does the channel 4 timer interrupt.
>
> Can someone make a suggestion as to how to make this work? Or if there
> is another way to make the counters count for several seconds I would
> be interested in that too.
>
> Thanks,
> Adlai >
>
> ------------------------------------------------------------------------
> >. > ------------------------------------------------------------------------
[Non-text portions of this message have been removed]
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
time as possible depending on your clock. Then in the interrupt routine
establish a sotware down counter to get to your overall large time. When
the SW counts down to 0, reset the down counter and do your thing.
Dave Dave adlai15 wrote:
> Hi,
>
> I would like to have my timers(Ch. 4 -7) interrupt me after a number
> of seconds have passed. It seems that the only way to do this is to
> use the Pulse Accumulator's clock PACLK and divide it by 65536 using
> the CLK1:0 bits in the PACTL.
>
> Currently I have IOC7 through IOC4 tied to GND, and am setting PACTL
> to 0x7C. But my channel 4 timer isn't getting interrupts. Only when I
> disable the Pulse Accumulator does the channel 4 timer interrupt.
>
> Can someone make a suggestion as to how to make this work? Or if there
> is another way to make the counters count for several seconds I would
> be interested in that too.
>
> Thanks,
> Adlai >
>
> ------------------------------------------------------------------------
> >. > ------------------------------------------------------------------------
[Non-text portions of this message have been removed]
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
Re: Getting the Pulse Accumulator working - Mark Butcher - Aug 24 17:31:00 2005
Hi
I managed to get the PA working as a timer by setting up channel 4
to generate a clock and using this clock an an input to the PA.
The PA generates an interrupt when it overflows so it is easy to
generate a delay by setting the PA counter to (0x0000 - delay). By
setting channel 4 to generate a high or a low frequency it is
possible to generate very short to quite long and very accurate
delays with an interrupt at the end.
Here is a bit of code without great details. It generates 3 PWM
outputs from channels 1..3 based on a 3kHz frequency at channel 4.
Channel 4 output is turned on when required to drive a buzzer signal
at 3kHz and also for use by the PA input to generate the desired
delay.
If you would like to see the code in action there is a demo at
www.mjbc.ch. You can download a program called 'VIPpanel' and
control the contrast and backlight of the LCD (along with other
things) via the Internet. The following PWMs are in use. You can
also generate variable 'beep' lengths but won't be able hear it of
course since the Webcam has no sound. Nevertheless you should get
the idea..
/***********************/
// Initialisation
#define CONTRAST_CONTROL TC6_HI
#define BACKLIGHT_CONTROL TC4_HI
#define LED_CONTROL TC5_HI
TIOS = (IOS7 | IOS6 | IOS5 | IOS4); // enable output compare on all
channels
OC7M = (OC7M6 | OC7M5 | OC7M4); // 3 channels as output (channel
7 (buzzer) not yet)
OC7D = (OC7D6 | OC7D5 | OC7D4); // transfer on channel 7 match
(for PWM)
TSCR1 = TEN; // enable timer
TCTL1 = 0x15; // toggle output for 3 channels
CONTRAST_CONTROL = (unsigned short)ucContrastSetting; //
set default contrast setting
LED_CONTROL = 0x00ff; // set max LED intensity
BACKLIGHT_CONTROL = 0x0000; // set min backlight intensity
(off)
TC7_HI = 0x00ff; // basic frequency is 3kHz
TSCR2 = 0x0c; // enable timer div = 32 // generate 3kHz tone for a specified period, interrupt from PA when
complete
#define FIXED_FREQUENCY 3000 // fixed frequency of buzzer
output
#define PERIOD_50MS (FIXED_FREQUENCY/20) //
((FIXED_FREQUENCY*50)/1000) // pulses in 50ms static void fnGenerateTone(unsigned char ucLength)
{
unsigned short usPeriodPulses = 0;
TCTL1 |= 0x40; // drive buzzer output
while (ucLength--) {
usPeriodPulses -= PERIOD_50MS;
}
PACNT_WORD = usPeriodPulses;
PACTL = (PAEN | PEDGE | PAOVI); // enable interrupt on overflow
}
// Interrupt due to pulse accumulator overflow
void Acc_Overflow(void)
{
PAFLG = PAOVF; // reset interrupt
TCTL1 &= ~0x40; // remove buzzer drive
PACTL = 0; // stop pulse accumulator activity
}
/**************************************************/ Regards
Mark Butcher
> adlai15 wrote:
>
> > Hi,
> >
> > I would like to have my timers(Ch. 4 -7) interrupt me after a
number
> > of seconds have passed. It seems that the only way to do this is
to
> > use the Pulse Accumulator's clock PACLK and divide it by 65536
using
> > the CLK1:0 bits in the PACTL.
> >
> > Currently I have IOC7 through IOC4 tied to GND, and am setting
PACTL
> > to 0x7C. But my channel 4 timer isn't getting interrupts. Only
when I
> > disable the Pulse Accumulator does the channel 4 timer interrupt.
> >
> > Can someone make a suggestion as to how to make this work? Or if
there
> > is another way to make the counters count for several seconds I
would
> > be interested in that too.
> >
> > Thanks,
> > Adlai
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
I managed to get the PA working as a timer by setting up channel 4
to generate a clock and using this clock an an input to the PA.
The PA generates an interrupt when it overflows so it is easy to
generate a delay by setting the PA counter to (0x0000 - delay). By
setting channel 4 to generate a high or a low frequency it is
possible to generate very short to quite long and very accurate
delays with an interrupt at the end.
Here is a bit of code without great details. It generates 3 PWM
outputs from channels 1..3 based on a 3kHz frequency at channel 4.
Channel 4 output is turned on when required to drive a buzzer signal
at 3kHz and also for use by the PA input to generate the desired
delay.
If you would like to see the code in action there is a demo at
www.mjbc.ch. You can download a program called 'VIPpanel' and
control the contrast and backlight of the LCD (along with other
things) via the Internet. The following PWMs are in use. You can
also generate variable 'beep' lengths but won't be able hear it of
course since the Webcam has no sound. Nevertheless you should get
the idea..
/***********************/
// Initialisation
#define CONTRAST_CONTROL TC6_HI
#define BACKLIGHT_CONTROL TC4_HI
#define LED_CONTROL TC5_HI
TIOS = (IOS7 | IOS6 | IOS5 | IOS4); // enable output compare on all
channels
OC7M = (OC7M6 | OC7M5 | OC7M4); // 3 channels as output (channel
7 (buzzer) not yet)
OC7D = (OC7D6 | OC7D5 | OC7D4); // transfer on channel 7 match
(for PWM)
TSCR1 = TEN; // enable timer
TCTL1 = 0x15; // toggle output for 3 channels
CONTRAST_CONTROL = (unsigned short)ucContrastSetting; //
set default contrast setting
LED_CONTROL = 0x00ff; // set max LED intensity
BACKLIGHT_CONTROL = 0x0000; // set min backlight intensity
(off)
TC7_HI = 0x00ff; // basic frequency is 3kHz
TSCR2 = 0x0c; // enable timer div = 32 // generate 3kHz tone for a specified period, interrupt from PA when
complete
#define FIXED_FREQUENCY 3000 // fixed frequency of buzzer
output
#define PERIOD_50MS (FIXED_FREQUENCY/20) //
((FIXED_FREQUENCY*50)/1000) // pulses in 50ms static void fnGenerateTone(unsigned char ucLength)
{
unsigned short usPeriodPulses = 0;
TCTL1 |= 0x40; // drive buzzer output
while (ucLength--) {
usPeriodPulses -= PERIOD_50MS;
}
PACNT_WORD = usPeriodPulses;
PACTL = (PAEN | PEDGE | PAOVI); // enable interrupt on overflow
}
// Interrupt due to pulse accumulator overflow
void Acc_Overflow(void)
{
PAFLG = PAOVF; // reset interrupt
TCTL1 &= ~0x40; // remove buzzer drive
PACTL = 0; // stop pulse accumulator activity
}
/**************************************************/ Regards
Mark Butcher
> adlai15 wrote:
>
> > Hi,
> >
> > I would like to have my timers(Ch. 4 -7) interrupt me after a
number
> > of seconds have passed. It seems that the only way to do this is
to
> > use the Pulse Accumulator's clock PACLK and divide it by 65536
using
> > the CLK1:0 bits in the PACTL.
> >
> > Currently I have IOC7 through IOC4 tied to GND, and am setting
PACTL
> > to 0x7C. But my channel 4 timer isn't getting interrupts. Only
when I
> > disable the Pulse Accumulator does the channel 4 timer interrupt.
> >
> > Can someone make a suggestion as to how to make this work? Or if
there
> > is another way to make the counters count for several seconds I
would
> > be interested in that too.
> >
> > Thanks,
> > Adlai
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
Re: Getting the Pulse Accumulator working - microcodefun - Aug 25 7:12:00 2005
Hi Adlai,
Especially the PWM subsystem is a tricky one to setup due to all the
clock configurations. If you'd like to save some time, you can use
Driver2Go (http://www.driver2go.net).
It contains (amongst others) HCS12 drivers for the PWM and ECT,
including multimedia tutorials on how to set it up.
-Frank
--- In 68HC12@68HC..., "adlai15" <adlai15@y...> wrote:
> Hi,
>
> I would like to have my timers(Ch. 4 -7) interrupt me after a
number
> of seconds have passed. It seems that the only way to do this is to
> use the Pulse Accumulator's clock PACLK and divide it by 65536
using
> the CLK1:0 bits in the PACTL.
>
> Currently I have IOC7 through IOC4 tied to GND, and am setting
PACTL
> to 0x7C. But my channel 4 timer isn't getting interrupts. Only when
I
> disable the Pulse Accumulator does the channel 4 timer interrupt.
>
> Can someone make a suggestion as to how to make this work? Or if
there
> is another way to make the counters count for several seconds I
would
> be interested in that too.
>
> Thanks,
> Adlai
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
Especially the PWM subsystem is a tricky one to setup due to all the
clock configurations. If you'd like to save some time, you can use
Driver2Go (http://www.driver2go.net).
It contains (amongst others) HCS12 drivers for the PWM and ECT,
including multimedia tutorials on how to set it up.
-Frank
--- In 68HC12@68HC..., "adlai15" <adlai15@y...> wrote:
> Hi,
>
> I would like to have my timers(Ch. 4 -7) interrupt me after a
number
> of seconds have passed. It seems that the only way to do this is to
> use the Pulse Accumulator's clock PACLK and divide it by 65536
using
> the CLK1:0 bits in the PACTL.
>
> Currently I have IOC7 through IOC4 tied to GND, and am setting
PACTL
> to 0x7C. But my channel 4 timer isn't getting interrupts. Only when
I
> disable the Pulse Accumulator does the channel 4 timer interrupt.
>
> Can someone make a suggestion as to how to make this work? Or if
there
> is another way to make the counters count for several seconds I
would
> be interested in that too.
>
> Thanks,
> Adlai
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )