[Moved] LPC2138 PWM to control servo motor

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Yes the frequency is around 200 hz .

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But for me i am getting 200hz even after turning on PLL in startup.s am i making any mistakes ?
 

Around 200Hz?
Are you using real hardware or simulation?
Have you changed the crystal to 12MHz from the default 10Mhz in the LPC2138 properties in proteus?

If you get 200Hz from the PIN then the core does indeed run at 12MHz

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Do you save the startup after the change and recompile?
 

Yes i saved the startup.s and recompiled it several times.
 

The latest uvision 4.6 cant open the file, I get an error "Can't open project fie timer.uvproj"

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I have opened the startup.s file you have included in a text editor, the PLL is not enabled

Code: 
[COLOR="#FF0000"]PLL_SETUP       EQU     0[/COLOR]
PLLCFG_Val      EQU     0x00000024

when you check the PLL checkbox in the wizard this becomes 1
 


For me it is showing deselected .
 

Also note that while the PWM is running you can't change the PWMMR values just by
Code: 
PWMMR2 = 0x0000004C;
PWMMR4 = 0x0000004A;

Read the datasheet, it explains what you have to do in order for the new value to be applied, read about PWMLER[/QUOTE]

I tried changing the PWMLER values it works but it fails to follow the conditions

Code: 
#include <LPC213x.h>
#include <math.h>





void input();
void adc_ini();
void adc_data();
void calculation();
void pwm();
void motor();

unsigned long val,adc_val;
float y,s,v,m;
float angle,b;


int main(void)
{
		input();
		pwm();
		
	
			while(1)
				{
	
							adc_ini();
							adc_data();
							calculation();

							
				}

}
		



void input(void)
{
	
    PINSEL0 = 0x00028000;     /* binary: 00000000_00000010_10000000_00000000 */
    IO0DIR = 0x80000000;     /* binary: 10000000_00000000_00000000_00000000 */
    PINSEL1 = 0x01000000;     /* binary: 00000001_00000000_00000000_00000000 */
    PINSEL2 = 0x00000000;     /* binary: 00000000_00000000_00000000_00000000 */
    IO1DIR = 0x00000000;     /* binary: 00000000_00000000_00000000_00000000 */

}	


void adc_ini(void)
{

    PCONP = (PCONP & 0x001817BE) | (1UL<<12);      /* Enable peripheral clock for ADC0 (default is enabled) */
		AD0INTEN = 0x00000000;     /* binary: 00000000_00000000_00000000_00000000 */
    AD0CR = 0x01200002;     /* binary: 00000001_00100000_00000000_00000010 */

}



void adc_data(void)
{
					while((AD0DR & 0x80000000)==0); //until bit 31 is high (DONE)
					val = AD0DR; //read a/d data register
					adc_val = ((val >> 6) & 0x3FF);    // Extract AD result
 } 
 
 




void calculation(void)
{
								/* angle calculation */
		
		m=(3.3/1023);/*3.3/1023 for adc conversion*/
		y=1.65;/*offset voltage */	
		s=0.8;/*sensitivity 800mv/g*/
		b=57.295;/* pi/180 for radian to degree conversion */
							
								/* formula tetha= arcsin( (vout - voffset)/sensitivity) */ 
	
		v=asin(((adc_val*m)-y)/s);
		angle=v*b;
		
                motor(); 
	
}



void pwm(void)
 {

                PCONP = (PCONP & 0x001817BE) | (1UL<<5);      /* Enable peripheral clock for PWM0 (default is enabled) */
                PWMTC = 0x00000000;     /* decimal 0 */
                PWMPR = 0x0000003B;     /* decimal 59 */
                PWMMCR = 0x00000002;     /* binary: 00000000_00000000_00000000_00000010 */
                PWMMR0 = 0x000003E8;     /* decimal 1000 */
		PWMMR2 = 0x0000004B;    
		PWMMR4 = 0x0000004B;   
		PWMPCR = 0x00001400;     /* binary: 00000000_00000000_00010100_00000000 */
                PWMTCR  = 0x09;     /* binary: 00001001 */
}



void motor(void)
{
      if(8.0>= angle <18.0)
	  {
			PWMLER = 0x0000014;
			PWMMR2 = 0x0000004C;     
			PWMMR4 = 0x0000004A;     
		}
		else
		{
			PWMLER = 0x0000014;
			PWMMR2 = 0x0000004B;     
			PWMMR4 = 0x0000004B; 	
		}
}
I changed PWMLER setting but even if the condition fails the following lines are getting executed
Code: 
                if(8.0>= angle <18.0)
	           {
			PWMLER = 0x0000014;
			PWMMR2 = 0x0000004C;     
			PWMMR4 = 0x0000004A;     
		   }
 
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kodi.sudar said:
For me it is showing deselected .
View attachment 85214
Click to expand...

But is is deselected, you said that the frequency doesn't change when you enable the PLL and I asked you to attach the code and in that PLL was not enabled, you were supposed to have it enabled in the project you have provided.

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if(8.0>= angle <18.0)
Click to expand...

That condition doesn't seem right to me or at least is not clear enough, use

Code: 
if ((angle<=8.0) && (angle<18.0))
although it doesn't make sense, if angle is less than 8 is there any chance that it will not be less than 18 too?

Also set the PWMLER after writing the new PWMMR values
 
 

Getting the same frequency with PLL on or off doesn't make sense, I'm not sure what you are doing wrong but works fine for me.
 

alexan_e said:
Getting the same frequency with PLL on or off doesn't make sense, I'm not sure what you are doing wrong but works fine for me.
Click to expand...


even i an trying to find out the problem. are you changing the clock frequency while creating new project ?

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Last edited:

The pll settings for a new project are like the ones I showed in post #16 , they give 60MHz, how can you be getting a different frequency?
 

alexan_e said:
The pll settings for a new project are like the ones I showed in post #16 , they give 60MHz, how can you be getting a different frequency?
Click to expand...
yes that is what i am thinking . let me check with the setting again.

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kodi.sudar said:
yes that is what i am thinking . let me check with the setting again.
Click to expand...
Can you zip your file and upload it ?
 

alexan_e said:
This is a project using the default startup that gives 60MHz
Click to expand...

still its confusing . i dont find any change in proteus output . PFA snapshot

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The condition works well when i set the condition using adc value
Code:

if ((adc_val>=0x0000022B) && (adc_val<0x0000024D))
{
PWMMR2 = 0x0000004C;
PWMMR4 = 0x0000004A;
PWMLER = 0x0000014;

but it fails to work when i assign using angle which is calculated using formula.
Code:

if ((angle >= 7.996409) && (angle < 18.20971))
{
PWMMR2 = 0x0000004C;
PWMMR4 = 0x0000004A;
PWMLER = 0x0000014;

}

Is there any thing wrong with the above condition ?
It works great in keil when i executed and checked by step one line ,But it fails to work in proteus simulation .
 

kodi.sudar said:
still its confusing . i dont find any change in proteus output
Click to expand...

Are you sure you are using the correct AXF/HEX file in the simulator?
Have you tried using my AXF file from the zip file, it should give 1ms

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kodi.sudar said:
It works great in keil when i executed and checked by step one line ,But it fails to work in proteus simulation .
Click to expand...

This may be related to a wrong AXF/HEX file or there is a problem with you proteus
 

alexan_e said:
Are you sure you are using the correct AXF/HEX file in the simulator?
Have you tried using my AXF file from the zip file, it should give 1ms

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This may be related to a wrong AXF/HEX file or there is a problem with you proteus
Click to expand...


Your hex file works well it gives the correct output.
Will the output changes due to AXF file ?
 

The AXF and HEX were generated with the same compile, the result will be the same.
Maybe you should consider updating your uvision to the latest version
 

alexan_e said:
The AXF and HEX were generated with the same compile, the result will be the same.
Maybe you should consider updating your uvision to the latest version
Click to expand...

I tried using your main.c as well as startup.s file by changing pll but gives the same output. but your hex file gives different output. Let me try with newer version of keil.

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kodi.sudar said:
I tried using your main.c as well as startup.s file by changing pll but gives the same output. but your hex file gives different output. Let me try with newer version of keil.
Click to expand...

Now it is working i tried to run the keil in administrator mode. . . I can see the change in the signal because the PLL setting.
Thanks
 
Last edited:

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