lpc 1347 PWM

[mateuszkiełbasa]

I am beginner. I would like to write simple program, which use pwm. I searched in manual but I didn't find any helpful information. Can someone tell in which chapter manual describes pwm? http://www.nxp.com/documents/user_manual/UM10524.pdf  . It will be Systick Handler? Thanks!

[sergedemaseneer]

I use a LPC1347 to control a RGBW ledstrip. The PWM frequency I use is 10kHz and is working to satisfaction.

[Badman]

Value set to show an example :smileyhappy:

Look at the picture:

If you want to reset the counter when it reaches the value of the MR0 register, you must set bit 1 in MCR

LPC_TMR16B0->MCR = 1<<1;


If you want to reset the counter when it reaches the value of the MR0 register and generate interrupt, you must set bit 0 and 1

LPC_TMR16B0->MCR = 1<<0 | 1<<1;

What frequency to work with PWM ?


[Badman]

No, You must use timer CT16B0/1 or CT32B0/1, see 16.7.12 PWM Control register and 17.7.12 PWM Control Register.
The following code, which I have not tested:

#include "LPC13xx.h"

int main(void) {

     /* IO CONFIG */
     LPC_SYSCON->SYSAHBCLKCTRL |= 1<<16;     // enable IOCON

     LPC_IOCON->PIO0_8 |= 0x2; // CT16B0_MAT0

     /* TIMER CONFIG */

     LPC_SYSCON->SYSAHBCLKCTRL |= 1<<7; // enable CT16B0

     LPC_TMR16B0->MR3 = 1000;     // timer period
     LPC_TMR16B0->MR0 = 500;          // 50% duty cycle
     LPC_TMR16B0->MCR |= 1<10;     // reset TC on match MR3
     LPC_TMR16B0->PWMC |= 1<0;     // enable PWM on CT16B0_MAT0


     LPC_TMR16B0->TCR = 1; // start timer and PWM

     while(1) {

    }
    return 0 ;
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Mateusz are you from Poland ?

[eleuterio]

Hi Tom,

Why did you choose a value of 1000 for the timer period?

I need to control an RGB LED through PWM and I'm having a hard time configuring the registers.. I have setup MR0-MR2 to control the three PWM signals I need, but I don't understand how to configure MCR. Any help would be greatly appreciated.

Thank you very much

[soledad]

Hi,

Please check the following tutorial and let me know if this helps.

LPC1768: PWM - Tutorials 

Have a great day,
Sol

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