topic PWM help in LPCXpresso IDE

PWM help

lpcware — Wed, 15 Jun 2016 23:03:29 GMT

Content originally posted in LPCWare by fplesinger on Thu Sep 23 06:33:04 MST 2010
Hi,
I would appreciate any links for PWM demos for use with LPC 1343. The one in default examples is not enough (for me. I jumped from Arduino and the change is ... quite difficult).

I managed how to control one PWM channel with 16bit timer. My project will need four PWM channels with 16bit timers and I am not able to switch them on simultaneously.

If anyone knows how to do this, please let me know.

Thanks!
Filip

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:30 GMT

Content originally posted in LPCWare by Jesse.Rosenberg on Thu Sep 23 15:01:31 MST 2010
Each of the timers in the LPC11xx/LPC13xx has an option to drive up to 3 Match/PWM outputs. If you need a total of 4 PWM outputs you will have to use both of the 16 bit timers.

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:30 GMT

Content originally posted in LPCWare by fplesinger on Fri Sep 24 01:46:29 MST 2010
Jesse, thank you for Your reply, it was helpfull.

Two PWM on one timer are now runnig, so ... it is on the good way :).

Thanks!
Filip

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:31 GMT

Content originally posted in LPCWare by Jesse.Rosenberg on Fri Sep 24 15:46:56 MST 2010
Flip,

Glad to hear it. I realize I only referred to 16 bit timers, but the 32bit timers would work equally well.

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:31 GMT

Content originally posted in LPCWare by mhjerde on Wed Sep 29 04:26:43 MST 2010
Hi
Here is an example of running 4 16-bit PWM outputs. Using the 32 bit counters works exactly the same... you would use LPC_TMR32B0 and LPC_TMR32B1, and connect to their respective pins.

/*************************************************************************//**
  Set up 16 bit counters CT16B0 and CT16B1 to run as PWM with a cycle
  length of 4096 (17.8kHz)

*****************************************************************************/
void PWM16_init(){


    LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 7);    // Enable clock to timer 0, CT16B0
    LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 8);    // Enable clock to timer 1, CT16B1

    // 16 bit timer 0 - CT16B0
    // PIO0_8 IS A
    LPC_IOCON->PIO0_8        |= 0x02;        // - set bit 1 to connect pin to CT16B0_MAT0
    LPC_IOCON->PIO0_8        &= ~(1 << 3);    // - clear bit 3 (and set 4: pull-up resistor)
    LPC_IOCON->PIO0_8        |= (1 << 4);    // - set bit 4

    // PIO0_9 IS C
    LPC_IOCON->PIO0_9        |= 0x02;        // - set bit 1 to connect pin to CT16B0_MAT1
    LPC_IOCON->PIO0_9        &= ~(1 << 3);    // - clear bit 3 (and set 4: pull-up resistor)
    LPC_IOCON->PIO0_9        |= (1 << 4);    // - set bit 4

    // 16 bit timer 1 - CT16B1
    // PIO1_9 IS B
    LPC_IOCON->PIO1_9        |= 0x01;        // - set bit 0 to connect pin to CT16B1_MAT0
    LPC_IOCON->PIO1_9        &= ~(1 << 3);    // - clear bit 3 (and set 4: pull-up resistor)
    LPC_IOCON->PIO1_9        |= (1 << 4);    // - set bit 4

    // PIO1_10 IS D
    LPC_IOCON->PIO1_10        |= 0x02;        // - set bit 1 to connect pin to CT16B1_MAT1
    LPC_IOCON->PIO1_10        &= ~(1 << 3);    // - clear bit 3 (and set 4: pull-up resistor)
    LPC_IOCON->PIO1_10        |= (1 << 4);    // - set bit 4

    LPC_TMR16B0->MCR     |= (1 << 10);        // Reset TC counter when it reaches Match Register 3 value
    LPC_TMR16B1->MCR     |= (1 << 10);        // Reset TC counter when it reaches Match Register 3 value

    LPC_TMR16B0->MR0 = 0;                // A duty cycle - TMR16B0 Match register 0
    LPC_TMR16B0->MR1 = 0;                // C duty cycle - TMR16B0 Match register 1
    LPC_TMR16B0->MR3 = 4096;            // Cycle length 4096 (= 17.8kHz) - Match register 3

    LPC_TMR16B1->MR0 = 0;                // B duty cycle - TMR16B1 Match register 0
    LPC_TMR16B1->MR1 = 0;                // D duty cycle - TMR16B1 Match register 1
    LPC_TMR16B1->MR3 = 4096;            // Cycle length 4096 (= 17.8kHz) - Match register 3

    LPC_TMR16B0->PWMC |= (1 << 0);        // A    Timer 0 MAT0 is PWM
    LPC_TMR16B0->PWMC |= (1 << 1);        // C    Timer 0 MAT1 is PWM
    LPC_TMR16B1->PWMC |= (1 << 0);        // B    Timer 1 MAT0 is PWM
    LPC_TMR16B1->PWMC |= (1 << 1);        // D    Timer 1 MAT1 is PWM

    LPC_GPIO0->DIR     |= (1 << 8);        // - select OUTPUT
    LPC_GPIO0->DIR     |= (1 << 9);        // - select OUTPUT
    LPC_GPIO1->DIR     |= (1 << 9);        // - select OUTPUT
    LPC_GPIO1->DIR     |= (1 << 10);        // - select OUTPUT
    
    LPC_TMR16B0->TCR = 1;    //enable timer 0
    LPC_TMR16B1->TCR = 1;    //enable timer 1

    return;
}

For the above example, you change the duty cycle by setting the four match registers MR0 add MR1 on TMR16B0 and TMR16B1 to any value between 0 and 4096.

Hope this helps.

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:32 GMT

Content originally posted in LPCWare by fplesinger on Wed Sep 29 06:53:28 MST 2010
Hi mhjerde,
many thanks for the example! It is very helpfull. Now I can see how it works..no more alchemy!:) ... So thanks!

Filip

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:33 GMT

Content originally posted in LPCWare by Lithium on Thu Apr 07 11:24:43 MST 2011
I was also looking for 4 pwm out on the lpc1343.
It works, i got a nice signal on my scope.

I wanted to connect the output to an servo motor or brushless motor.
The motor will not turn on any value at all, could it be the frequency of the signal?

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:33 GMT

Content originally posted in LPCWare by Ex-Zero on Thu Apr 07 11:53:24 MST 2011
Which Power Driver did you use?

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:34 GMT

Content originally posted in LPCWare by Lithium on Thu Apr 07 12:35:36 MST 2011
I am using this driver: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=6458

I need a signal at 400hz for example.
I measured the pwm out from the receiver. The signal is 2ms high and 2ms low.

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:34 GMT

Content originally posted in LPCWare by Ex-Zero on Thu Apr 07 13:15:13 MST 2011

Quote: Lithium
I measured the pwm out from the receiver. The signal is 2ms high and 2ms low.

And what's happening then :confused::confused:

So you are trying to use an LPC1343 to generate a signal for an ATMega8L, which drives your motor?

Anyway, did you try a standard signal (50Hz, 1-2ms pulse)?

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:35 GMT

Content originally posted in LPCWare by Lithium on Thu Apr 07 13:19:29 MST 2011
I need to have a pwm signal with 2ms high at 50% duty cycle.
The program given above has a frequency of 17.8khz. That is way to fast.
Most drivers can only read signals about 2ms.

Yes indeed, the ESC drives the motor, got 4 of them.
I did not tried to make a signal about 2ms, it is difficult for me to use interrupt etc.
I was looking for an working program and found this.

I was thinking how to make my own pwm output. Hope you could help me with it.
Make a timer until the 2ms max for example.
Use 4 var's where i can set the a number.
If the counter is greater then that number, put it high. Is it lower then put it low.
That could give me a pwm ouput.

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:35 GMT

Content originally posted in LPCWare by Ex-Zero on Thu Apr 07 14:29:41 MST 2011

Quote:

I need to have a pwm signal with 2ms high at 50% duty cycle.

Are you kidding me?

Just add a prescaler:

 LPC_TMR16B0->PR  = 71;     //timer base: 72MHz / (Prescaler+1) = 1MHz

and select match register:

LPC_TMR16B0->MR0 = 2000;                // A duty cycle - TMR16B0 Match reg0 2000*1µs = 2ms
LPC_TMR16B0->MR1 = 2000;                // C duty cycle - TMR16B0 Match reg1
LPC_TMR16B0->MR3 = 4000;                // Cycle length 4000*1µs = 4ms

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:36 GMT

Content originally posted in LPCWare by Lithium on Fri Apr 08 01:29:16 MST 2011
Cool that works perfectly :)
The prescaler did the job.

Thank you :)

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:37 GMT

Content originally posted in LPCWare by bobi-one on Sat Apr 09 15:46:55 MST 2011
How about GPIO 1.0 on the lpc1343? Is pwm on it run by different way?

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:38 GMT

Content originally posted in LPCWare by Ex-Zero on Sat Apr 09 16:03:43 MST 2011

Quote: bobi-one
How about GPIO 1.0 on the lpc1343? Is pwm on it run by different way?

Yes, it's different. It doesn't run at all :)

PIO1_0 is capture input (CT32B1_CAP0).

If you want to use PWM you need Match output (of 16bit or 32bit timer).

This sample uses 16 bit timer0/1 to generate PWM at
[INDENT]PIO0_8 = CT16B0_MAT0
PIO0_9 = CT16B0_MAT1
PIO1_9 = CT16B1_MAT0
PIO1_10= CT16B1_MAT1
[/INDENT]

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:38 GMT

Content originally posted in LPCWare by bobi-one on Sun Apr 10 02:25:53 MST 2011

Quote: Zero
Yes, it's different. It doesn't run at all :)

PIO1_0 is capture input (CT32B1_CAP0).

If you want to use PWM you need Match output (of 16bit or 32bit timer).

This sample uses 16 bit timer0/1 to generate PWM at
[INDENT]PIO0_8 = CT16B0_MAT0
PIO0_9 = CT16B0_MAT1
PIO1_9 = CT16B1_MAT0
PIO1_10= CT16B1_MAT1
[/INDENT]

Ðžh Oh, this means I have to redesign my board( x-acto + kynar wire :)).

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:39 GMT

Content originally posted in LPCWare by cesimkaol on Fri Jun 17 17:47:54 MST 2011
Same as me,I set my PR register to 71 and set MR0 to 500000 for 0.5ms period and %50 duty cycle.However I dont know how you set that duty cycle?

its clear that give me an information about how to calculate period but I dont have an idea or knowledge about that %50 duty cycle...how do we calculate it or in which formula calculate it...for example if I want to have %10 duty - cycle then what should I do?

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:40 GMT

Content originally posted in LPCWare by Ex-Zero on Fri Jun 17 18:32:15 MST 2011

Quote: cesimkaol
...but I dont have an idea or knowledge about that %50 duty cycle...how do we calculate it or in which formula calculate it...for example if I want to have %10 duty - cycle then what should I do?

What's not clear there?

Quote: Zero
Are you kidding me?

Just add a prescaler:

 LPC_TMR16B0->PR  = 71;     //timer base: 72MHz / (Prescaler+1) = 1MHz

and select match register:

LPC_TMR16B0->MR0 = 2000;                // A duty cycle - TMR16B0 Match reg0 2000*1µs = 2ms
LPC_TMR16B0->MR1 = 2000;                // C duty cycle - TMR16B0 Match reg1
LPC_TMR16B0->MR3 = 4000;                // Cycle length 4000*1µs = 4ms

Re: PWM help

lpcware — Wed, 15 Jun 2016 23:03:40 GMT

Content originally posted in LPCWare by cesimkaol on Mon Jun 20 07:42:17 MST 2011
Thank you zero ....problem solved.I will be here again with problems :)