Code Improvement

Hi everyone, once again!

Hi made this code for controlling a DC motor with a PIC12F683.
The PIC reads the ADC value, and then controls the duty of the PWM output.

Everything is working good, however, i like to know your opinion about the code.

Is it possible to make any improvement, or other change to put the code better?

Here is the code

Code:

---

'****************************************************************
'*  Name    : PWM.BAS                                          *
'*  Author  : Gadelhas                                          *
'*  Notice  : Copyright (c) 2010                                *
'*          : All Rights Reserved                              *
'*  Date    : 28-11-2010                                        *
'*  Version : 1.0                                              *
'*  Notes  :                                                  *
'*          : PIC12F683  + MICROCODE + EASYPICV6                *
'****************************************************************
'                        INCLUDE's e FUSES
' ====================================================================
@ __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF & _BOD_OFF

' ====================================================================
 Define OSC 8
'                              VARIABLES
' ===========================================================
 Duty    var WORD: DUTY=0
 AdcValue var word: AdcValue=0
 I        var word: I=0
 Sample  var word: sample=0
 
'                      REGISTERS & PINOUT 1 = IN; 0 = OUT
' ====================================================================
              '76543210
 TRISIO    = %00000001
 
              '76543210
  GPIO    = %00000000
 
 ANSEL = 1       
 VRCON = 0
 CMCON0 = 7       
 ADCON0 = %10000000 

'                              PINOUT NAMES
' ===========================================================
 POT1      VAR GPIO.0

'                              DEFINITIONS
' ===========================================================
 DEFINE ADC_BITS 10    ' Set number of bits in result
 DEFINE ADC_CLOCK 3    ' Set clock source (rc = 3)
 DEFINE ADC_SAMPLEUS 50 ' Set sampling time in microseconds
 
'                            MAIN PROGRAM
' ===========================================================
Main:
  gosub ADC
  DUTY=(AdcValue*64)/256 
  HPWM 1, DUTY, 5000   
GOTO MAIN

'                          SUB-ROTINAS
' ===========================================================
ADC:
  for I = 1 to 15
        ADCON0.1 = 1                           
        Not_Done:                             
        if ADCON0.1 = 1 then not_done 
        adcin 0,AdcValue                             
        sample = AdcValue  + sample
    next I
    AdcValue  = sample/15   
    sample=0 
return
END

---

Thanks

Short, sweet, and works...
Looks good!!!

Muliplying by 64 and dividing by 256 is equivalent to dividing by 4.
Dividing by powers of 2 is easily done with shifts. To divide by 4, right shift two places (>> 2)

And.. the HPWM command in PBP is limiting. If you write directly to CCPRxL, and CCPxCON4:5 you can get PWM frequencies that are easy to filter with an L-C network + Schottky diode (above 100Khz is easily obtainable). That way, your motor sees nearly pure DC. A lot of brushless motors really prefer not to have a "chopped" power input.

You can remove all the division if:

loop 16 times

for I = 0 to 15

Since Charles has suggested to simplify deviding by 4 , then 16 x 4 = 64, so if you devide by 64 you will do only one division.

AdcValue = sample/64

or

AdcValue = sample >> 6


Hence, you don't need to change variable:

HPWM 1, AdcValue, 5000

Naturaly writing to CCPRxL, and CCPxCON4:5, as suggested in the previuos post is an additional improvement.



Cheers

Alberto

Hi Everyone, and many thanks for the answers to my post!!!

Hi follow your opinions and i change the code to this;

Code:

---

'****************************************************************
'*  Name    : PWM.BAS                                          *
'*  Author  : Gadelhas                                          *
'*  Notice  : Copyright (c) 2010                                *
'*          : All Rights Reserved                              *
'*  Date    : 28-11-2010                                        *
'*  Version : 1.0                                              *
'*  Notes  :                                                  *
'*          : PIC12F683  + MICROCODE + EASYPICV6                *
'****************************************************************
'                        INCLUDE's e FUSES
' ====================================================================
@ __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF & _BOD_OFF

' ====================================================================
 Define OSC 8
'                              VARIÁVEIS
' ====================================================================
 AdcValue var word: AdcValue=0
 I        var word: I=0
 Sample  var word: sample=0
 
'                      REGISTOS E PINOUT 1 = IN; 0 = OUT
' ====================================================================
              '76543210
 TRISIO    = %00000001
 
              '76543210
  GPIO    = %00000000
 
 ANSEL = 1  'GP0 AANALOG           
 VRCON = 0  'VREF OFF
 CMCON0 = 7 'COMPARATOR OFF           
 ADCON0 = %10000000  'RIGHT JUSTIFY - 128
 
 PR2    = %00011000 'SET 24 - 5000Hz - 8Bits
 T2CON  = %00000110 'TIMER2 ON - PRESCALER 1:16 - Max Duty Value 100 - 1% Step
 CCPR1L  = %00000000
 CCP1CON = %00001100 'PWM ON

'                              NOMES PINOUT
' ====================================================================
 POT1      VAR GPIO.0

'                              DEFINIÇÕES
' ====================================================================
 DEFINE ADC_BITS 10    ' Set number of bits in result
 DEFINE ADC_CLOCK 3    ' Set clock source (rc = 3)
 DEFINE ADC_SAMPLEUS 50 ' Set sampling time in microseconds
 
'                            INICIO PROGRAMA
' ====================================================================
Main:
  gosub ADC
  CCPR1L.7=AdcValue.9
  CCPR1L.6=AdcValue.8
  CCPR1L.5=AdcValue.7
  CCPR1L.4=AdcValue.6
  CCPR1L.3=AdcValue.5
  CCPR1L.2=AdcValue.4
  CCPR1L.1=AdcValue.3
  CCPR1L.0=AdcValue.2 
  CCP1CON.5=AdcValue.1
  CCP1CON.4=AdcValue.0     
GOTO MAIN

'                          SUB-ROTINAS
' ====================================================================
ADC:
  for I = 1 to 15
        ADCON0.1 = 1                           
        Not_Done:                             
        if ADCON0.1 = 1 then not_done 
        adcin 0,AdcValue                             
        sample = AdcValue  + sample
    next I
    AdcValue = (sample/163) 
    sample=0 
return
END

---

The code works great. Initially it had 288 words, after change went to 213 words.
Is it possible to improve this piece of code?;

Code:

---

  CCPR1L.7=AdcValue.9
  CCPR1L.6=AdcValue.8
  CCPR1L.5=AdcValue.7
  CCPR1L.4=AdcValue.6
  CCPR1L.3=AdcValue.5
  CCPR1L.2=AdcValue.4
  CCPR1L.1=AdcValue.3
  CCPR1L.0=AdcValue.2 
  CCP1CON.5=AdcValue.1
  CCP1CON.4=AdcValue.0

---

Is this correct?

>>1 is the same as devide by 2
>>2 is the same as devide by 4
>>3 is the same as devide by 8
>>4 is the same as devide by 16
>>5 is the same as devide by 32
>>6 is the same as devide by 64
>>7 is the same as devide by 128
>>8 is the same as devide by 256

and

<<1 is the same as multiply by 2
<<2 is the same as multiply by 4
<<3 is the same as multiply by 8
<<4 is the same as multiply by 16
<<5 is the same as multiply by 32
<<6 is the same as multiply by 64
<<7 is the same as multiply by 128
<<8 is the same as multiply by 256

Thanks once again to everyone!!

One thing you could do is -

CCPR1L = AdcValue >> 2

CCP1CON.5=AdcValue.1
CCP1CON.4=AdcValue.0