Simple PWM timer setup for LPC1343

[lpcware]

Content originally posted in LPCWare by Brinkand on Wed Feb 17 05:47:26 MST 2010
I wanted a simple piece of setup code for the Xpresso demo board to test PWM. Starting with the blinky project and cutting out the pieces I did not need, I arrived at the below code.

Most of You probably do this in minutes, but maybe I can help a single soul by posting my resulting code.

The timer is set up with PWM on MAT0 of TMR16B1 and a toggling output on MAT1. MR3 used to set cycle length.

I noted that the init_timer16() actually sets pull up on outputs:-)

  // PWM output: 16bit_timer1
  //init_timer16(1, 14399); // 14399 gives 5kHz with 72MHz clock.
  // Timer set up for 5KHz 20% DC PWM on MAT0 and
  // 2.5kHz toggling signal with phase offset at MAT1.
  // This is not for any specific application, just for testing.
  LPC_SYSCON->SYSAHBCLKCTRL |= (1<<8);  // Enable clock to timer 1
  //LPC_IOCON->PIO1_8           &= ~0x07;    /*  Timer1_16 I/O config  */
  //LPC_IOCON->PIO1_8           |= 0x01;        /* Timer1_16 CAP0    - set bit 1*/
  // default: 0xD0 = 0b11010000 (at boot) - after this: 0b11010001 - means MAT0 enabled + pull up + some undocumented bits.
  // Frankly there is no reason for pull-up on output.
  //LPC_IOCON->PIO1_9           &= ~0x07;                               // - remove bits 0,1 & 2
  LPC_IOCON->PIO1_9           &= ~0x1F;                               // - remove bits 0,1 & 2 and pull resistors
  LPC_IOCON->PIO1_9           |= 0x01;        /* Timer1_16 MAT0 */ //- set bit 1
  //LPC_IOCON->PIO1_10          &= ~0x07;
  LPC_IOCON->PIO1_10          &= ~0x1F;     // - remove bits 0,1 & 2 and pull resistors
  LPC_IOCON->PIO1_10          |= 0x02;        /* Timer1_16 MAT1 */

  /* Enable the TIMER1 Interrupt */
  // NVIC_EnableIRQ(TIMER_16_1_IRQn);  // No interrupt needed.

  LPC_TMR16B1->MCR = 0x0400;        /* Reset at MR3*/
  //LPC_TMR16B1->MCR |= 0x0400;        /* MR1 setup*/
  LPC_TMR16B1->MR0 = 11421;            /* Match register 0 - Turn on time: 2879 = 20% duty cycle */
  LPC_TMR16B1->MR1 = 7000;            /* Match register 1 - no PWM - toggle test */
  //LPC_TMR16B1->MR2 = 0;                /* Match register 2 - not used */
  LPC_TMR16B1->MR3 = 14399;          /* Match register 3 - cycle length */
  LPC_TMR16B1->EMR = 0xC2;            /* External Match register Settings for PWM channel have no effect.*/
  LPC_TMR16B1->PWMC = 0x01;             /* PWMC register -MAT0 is PWM. */
  // PIO1_9 = TC16B1_MAT0
  GPIOSetDir( 1, 9, 1 );  // Set as output
  // PIO1_10 = TC16B1_MAT1
  GPIOSetDir( 1, 10, 1 ); // set as output
  LPC_TMR16B1->TCR = 1;   // Enable timer 1

[lpcware]

Content originally posted in LPCWare by stefi on Thu Apr 10 03:45:12 MST 2014
I want to increase intensity gradually...please help me...please

[lpcware]

Content originally posted in LPCWare by stefi on Wed Mar 19 22:58:27 MST 2014
how can i change intensity of led using pwm gradually?

[lpcware]

Content originally posted in LPCWare by stefi on Mon Feb 03 03:11:15 MST 2014
how can i read simple pir sensor using lpc1343 in lpcxpresso? & how can i get the printed
readings of pir sensor in console window?
please help me ....

[lpcware]

Content originally posted in LPCWare by stefi on Tue Jan 28 02:24:22 MST 2014
thanx

[lpcware]

Content originally posted in LPCWare by serge on Tue Jan 28 02:22:49 MST 2014
user manual 10375
chapter 15

[lpcware]

Content originally posted in LPCWare by R2D2 on Tue Jan 28 01:26:03 MST 2014

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Quote: stefi
...make the above code simper?????

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You're kidding. That sample[color=#f00] is[/color] simple.

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Quote: stefi
In above code i didnt get that..what are thoes values...14399,14211 assigned to the match registers... and how it comes??

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Could be useful to read timer description of UM.

14399 is obviously the cycle length in MR3: 72MHz / (14399 +1) = 5 kHz

11421 should be the switching point (80%)in MR0.

That's obviously a typo, this value should be 11520...

[lpcware]

Content originally posted in LPCWare by stefi on Tue Jan 28 00:48:17 MST 2014
actually i m a student of b.e 4th year. And i m doing my project using this software. But i found this too much tough.Can u help me to make the above code simper?????

In above code i didnt get that..what are thoes values...14399,14211 assigned to the match registers... and how it comes??

[lpcware]

Content originally posted in LPCWare by R2D2 on Tue Jan 28 00:23:02 MST 2014

---

Quote: stefi
Please,help me in coding for changing the intensity of led with the help of pwm in lpc1343 in lpcxpresso...please...please

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What's wrong with the PWM sample above ????????????  :quest:

[lpcware]

Content originally posted in LPCWare by stefi on Tue Jan 28 00:18:53 MST 2014
Please,help me in coding for changing the intensity of led with the help of pwm in lpc1343 in lpcxpresso...please...please

[lpcware]

Content originally posted in LPCWare by ub3r on Sat Oct 08 09:00:58 MST 2011

[SIZE=2]void setPWM(void)
{
// PWM output: 16bit_timer1
// init_timer16(1, 14399); // 14399 gives 5kHz with 72MHz clock.
// Timer set up for 5KHz 20% DC PWM on MAT0 and
// 2.5kHz toggling signal with phase offset at MAT1.
// This is not for any specific application, just for testing.

LPC_SYSCON->SYSAHBCLKCTRL |= (1<<8);  // Enable clock to timer 1
LPC_IOCON->PIO1_9           |= 0x01;        /* Timer1_16 MAT0 */ //- set bit 1

/* Enable the TIMER1 Interrupt */
// NVIC_EnableIRQ(TIMER_16_1_IRQn);  // No interrupt needed.

LPC_TMR16B1->MCR = 0x0400;       /* Reset at MR3*/
LPC_TMR16B1->MR0 = 11421;        /* Match register 0 - Turn on time: 2879 = 20% duty cycle */
LPC_TMR16B1->MR3 = 14399;        /* Match register 3 - cycle length */
LPC_TMR16B1->PWMC = 0x01;         /* PWMC register -MAT0 is PWM. */
GPIOSetDir( 1, 9, 1 );  // Set as output
LPC_TMR16B1->TCR = 1;   // Enable timer 1
}[/SIZE]

[lpcware]

Content originally posted in LPCWare by sakka.haythem.esim on Wed Aug 17 05:29:53 MST 2011
hello,
Could someone help to set PIO1_10 as Timer1_16 MAT0 and PIO2_3 as Timer1_16 MAT1?
Thinks!
Haythem