PWM on LPC1343

[lpcware]

Content originally posted in LPCWare by tinto on Fri Jan 13 00:23:40 MST 2012
Could someone help me to find out the error in this program? I built the program successfully using LPCXpresso and debugged with the LPC1343 development board. But I am not getting any PWM at the output pins. The output is always high. What is the problem with this code?

#include "LPC13xx.h"

int main(void)
{
/*************************************************************************//**
  Set up 16 bit counters CT16B0 and CT16B1 to run as PWM with a cycle
  length of 4096
*****************************************************************************/

    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->EMR |= 0x000000F0;// Toggle output when a match occurs with MR0 and MR1
    LPC_TMR16B1->EMR |= 0x000000F0;// Toggle output when a match occurs with MR0 and MR1

    LPC_TMR16B0->MR0 = 2048;// A duty cycle - TMR16B0 Match register 0
    LPC_TMR16B0->MR1 = 2048;            // C duty cycle - TMR16B0 Match register 1
    LPC_TMR16B0->MR3 = 4096;            // Cycle length 4096 (= 17.8kHz) - Match register 3

    LPC_TMR16B1->MR0 = 2048;            // B duty cycle - TMR16B1 Match register 0
    LPC_TMR16B1->MR1 = 2048;            // 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

while(1){}
}

[lpcware]

Content originally posted in LPCWare by tinto on Mon Jan 16 01:55:54 MST 2012
Thanks a lot for your replies. Now everything works fine.

[lpcware]

Content originally posted in LPCWare by Rob65 on Sun Jan 15 01:17:21 MST 2012

---

Quote: tinto
But before that, can you please guide me how to create a new project in LPCXpresso?
...

Is this the right way? I am a very beginner. Please help me.

---

There is a very good "Getting Started" that is installed together with the LPCXpresso tools. After installation you even have to untick a box in order not to get it on your screen :eek:
I know ... I also always untick the "Open readme.txt" stuff that comes with installations...

This manual can be found in Window's start menu (all programs -. LPCXpresso v4.1.5_219 -> Help and Guides -> Getting Started
It explains how to start importing the examples, building them, debugging your code, creating a new workspace, creating a new project, how to recover your board if it stopped working and much more.

Believe it or not, I did read this manual even though I have a > 20 years profession in embedded software development.

Regards,[INDENT]Rob

-- if everything else fails, read the manual
[/INDENT]

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Sun Jan 15 00:06:55 MST 2012
You should create a LPCXpresso project with CMSIS included. This should be done if you use project wizard:

File-> New -> Project: project wizard is opening

Select 'LPCXpresso C Project', Click Next

Select your project type: 'C project' or 'Semihosting C project', use semihosting to use console output, Click Next

Enter a project name, Click Next

Select your mcu, Click Next

Select options (let the wizard include CMSIS and CRP) and click Finish

Now your project wizard should create you a complete project, CMSIS included and ready to start :)

You can also find a few informative videos in section 'More Information-Literature' of

http://ics.nxp.com/lpcxpresso/

[lpcware]

Content originally posted in LPCWare by tinto on Sat Jan 14 23:14:28 MST 2012
Thank you very much for your replies. I will try your codes as well as my code. But before that, can you please guide me how to create a new project in LPCXpresso? I think that I am going some where wrong in the steps.
I used to create a new project in the following way.
File>New> Project>C project (C/C++)>Project Name>LPCXpresso empty C project>Select both Debug and Release>Select LPC1343>Finish. Now I add a folder to file named src and add the program.c file as well as the necessary header files to  the src folder. Then Build and Debug.
Is this the right way? I am a very beginner. Please help me.

[lpcware]

Content originally posted in LPCWare by vasanth on Sat Jan 14 09:43:47 MST 2012
To Zero,

   Now we have a reference to [I]'I'm clean' [/I]code because of that [I]'I'm confused'[/I] code...:D
You must be kept in a seperate league in this forum. I would say "super senior member" is a good name for that category.


To NxP,

        /* Setup the external match register */
        LPC_TMR16B1->EMR = (1<<EMC3)|(1<<EMC2)|(1<<EMC1)|(2<<EMC0)|(1<<3)|(match_enable);

  This code is from an example provided by NxP for PWM (for LPC1100),
The  EMR register has been written needlessly as our "super senior member"  has pointed out. I wouldn't complain this as a serious problem, because this is another way to control the initial state of those MAT pins, but this  is a good way to confuse a beginner :confused: which includes myself...:eek:.

What we need in these examples is much more clearer

/* comments... */
/* comments... */
/* comments... */

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Sat Jan 14 06:52:16 MST 2012
:mad: Forgotten #7 :mad:

#7: Switching PWM outputs continuously high or low can be done with MR register setting without stopping timer:

//switching PIO0_8 low/high/low/PWM(1kHz)
 i=0;while(i<100000){i++;}                //delay
 LPC_TMR16B0->MR0 =LPC_TMR16B0->MR3+1;  //match register > reset register => output low
 i=0;while(i<100000){i++;}                //delay
 LPC_TMR16B0->MR0 =0;                      //match register = 0 => output high
 i=0;while(i<100000){i++;}                //delay
 LPC_TMR16B0->MR0 =LPC_TMR16B0->MR3+1;  //match register > reset register => output low
 i=0;while(i<100000){i++;}                //delay
//reset counter to get full PWM cycle again, don't use this command
//if other MAT outputs of this timer are still working 
//LPC_TMR16B0->TC  = 0;                    //reset counter
 LPC_TMR16B0->MR0 =LPC_TMR16B0->MR3/4;  //valid match register again

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Sat Jan 14 03:42:29 MST 2012
Although this code is running :eek:, I wouldn't go so far to say it's good. It's an[I] 'I'm confused'[/I] code :rolleyes:

#1: Setting direction for non GPIO-functions is nonsense, so don't try to set PWM outputs as GPIO outputs.

 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

#2: If you enable PWM you don't need to care about setting/resetting PWM outputs, so EMC settings in EMR are useless:

 LPC_TMR16B0->EMR |= 0x000000F0;      // Toggle output when a match occurs with MR0 and MR1
 LPC_TMR16B1->EMR |= 0x000000F0;      // Toggle output when a match occurs with MR0 and MR1

#3: EMR can be used to force outputs high or low with EM0-EM3 bits as shown in sample below.

#4: To generate more readable code you should set/reset bits in blocks like function, mode...

//PIO0_8
 LPC_IOCON->PIO0_8 &= ~((1<<10)|(1<<5)|(3<<3)|(7<<0)); //reset func,mode,hys,OD
 LPC_IOCON->PIO0_8 |=  ((2<<3)|(2<<0));                   //set CT16B0 MAT0, pullup

#5: Prescale Counter register is also helping to generate more readable code. Just use it as divider.

//set prescaler
 LPC_TMR16B0->PR  = 71;                    //prescaler:72 -> time base: 1/1MHz = 1µs

#6: If this sample isn't running you're not using a standard LPCXpresso project and should check basic settings like IOCON clock...

int main(void)
{
 volatile unsigned int i;
 printf("PWM16 Sample\n");
//Init PWM
 LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 7);        //enables clock for 16-bit counter/timer 0
 LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 8);        //enables clock for 16-bit counter/timer 1
//PIO0_8
 LPC_IOCON->PIO0_8 &= ~((1<<10)|(1<<5)|(3<<3)|(7<<0)); //reset func,mode,hys,OD
 LPC_IOCON->PIO0_8 |=  ((2<<3)|(2<<0));                   //set CT16B0 MAT0, pullup
//PIO0_9
 LPC_IOCON->PIO0_9 &= ~((1<<10)|(1<<5)|(3<<3)|(7<<0)); //reset func,mode,hys,OD
 LPC_IOCON->PIO0_9 |=  ((2<<3)|(2<<0));                   //set CT16B0 MAT1, pullup
//PIO1_9
 LPC_IOCON->PIO1_9 &= ~((1<<10)|(1<<5)|(3<<3)|(7<<0)); //reset func,mode,hys,OD
 LPC_IOCON->PIO1_9 |=  ((2<<3)|(1<<0));                   //set CT16B1 MAT0, pullup
//PIO1_10
 LPC_IOCON->PIO1_10 &= ~((1<<10)|(1<<7)|(1<<5)|(3<<3)|(7<<0)); //reset func,mode,hys,admode,OD
 LPC_IOCON->PIO1_10 |=  ((1<<7)|(2<<3)|(2<<0));                //set CT16B1 MAT1, pullup, digital

//set match / interrupts
 LPC_TMR16B0->MCR = (1 << 10);            //MR3 reset, no interrupts
 LPC_TMR16B1->MCR = (1 << 10);            //MR3 reset, no interrupts

//set prescaler
 LPC_TMR16B0->PR  = 71;                    //prescaler:72 -> time base: 1/1MHz = 1µs
 LPC_TMR16B1->PR  = 71;                    //prescaler:72 -> time base: 1/1MHz = 1µs

 LPC_TMR16B0->MR3 = 1000;                //cycle: 1000µs = 1kHz
 LPC_TMR16B0->MR0 = LPC_TMR16B0->MR3/4;    //MAT0 1/4 low, 3/4 high
 LPC_TMR16B0->MR1 = LPC_TMR16B0->MR3/2;    //MAT1 1/2 low, 1/2 high

 LPC_TMR16B1->MR3 = 500;                //cycle: 500µs = 2kHz
 LPC_TMR16B1->MR0 = LPC_TMR16B1->MR3/4;    //MAT0 1/4 low, 3/4 high
 LPC_TMR16B1->MR1 = LPC_TMR16B1->MR3/2;    //MAT1 1/2 low, 1/2 high

 LPC_TMR16B0->PWMC = ((1<<0)|(1<<1));    //enable PMM MAT0/MAT1
 LPC_TMR16B1->PWMC = ((1<<0)|(1<<1));    //enable PMM MAT0/MAT1

 LPC_TMR16B0->TCR = 1;                    //start timer 0
 LPC_TMR16B1->TCR = 1;                    //start timer 1

 while(1)
 {
//switching PIO0_8 low/high/low/PWM(1kHz)
  i=0;while(i<100000){i++;}                //delay

  LPC_TMR16B0->TCR = 0;                    //stop timer 0
  LPC_TMR16B0->EMR &=~(1<<0);            //force CT16B0 MAT0 low

  i=0;while(i<100000){i++;}                //delay

  LPC_TMR16B0->EMR |= (1<<0);            //force CT16B0 MAT0 high

  i=0;while(i<100000){i++;}                //delay

  LPC_TMR16B0->EMR &=~(1<<0);            //force CT16B0 MAT0 low

  i=0;while(i<100000){i++;}                //delay

  LPC_TMR16B0->TC  = 0;                    //reset counter
  LPC_TMR16B0->TCR = 1;                    //start timer 0
 }
 return 0 ;
}

[lpcware]

Content originally posted in LPCWare by vasanth on Fri Jan 13 22:47:05 MST 2012

---

Quote: tinto
I am not getting any PWM at the output pins. The output is always high. What is the problem with this code?

---

If my eye is good, my scope shows PWM with your code running on my board.... :)