Hello fellow EE Brothers,

I'm trying to code a very simple proportional controller for the first steps of my internship.

I'm acquiring an analog continuous signal let's say with voltage between 0 and 5V. I do it through AN0... and then I want to generate a PWM... my problem is that I don't know how to translate the output of the DAC into PWM multiplied by the proportional factor.

Here's my code, I'm using the CC5X free compiler:

#include "int16CXX.H"


// pic initialisation routine
void init(void)
{
// CONFIGURATION DES PORTS A/B/C
ANSEL =0b.0000.0001; // A0(AN0) en ANA (les autres en I/O)
ANSELH=0b.0000.0000; // PORTA/B/C en I/O
TRISA =0b.1111.1111; // configuration portA : XXEE EEEE
TRISB =0b.0111.1111; // configuration portB : SEEE XXXX
TRISC =0b.1111.1100; // configuration portB : EEEE EESS

// CONFIGURATION DU CAN
ADCON1=0; // TDA=100ns
ADCON0=1; // active le CAN (AN0, ref à 5V)

return;
}


// main routine
void main()
{
init(); // pic initialization

for(...)
{
// 1 - acquisition d'un échantillon
ADCON0.1=1; // lance une conversion sur AN0
while(ADCON0.1==1); // attend la fin de l'acquisition sur AN0

/*
* PWM registers configuration
* Fosc = 20000000 Hz
* Fpwm = 4006.41 Hz
* Duty Cycle = 50 %
* Resolution is 10 bits
* Prescaler is 16
*/
PR2 = 0b01001101 ;
T2CON = 0b00000111 ;
CCPR1L = 0b00100110 ;
CCP1CON = 0b00111100 ;

// This is were I'm stuck... ?? = ADRESH; // émission de l'acquisition sur AN0


// 2 - détection de la saturation
if(ADRESH>0xA0) PORTC.1=1; else PORTC.1=0; // > 50% : LED verte
if(ADRESH==0xFF) PORTC.0=1; else PORTC.0=0; // saturation : LED rouge
}
}

In the code, I've mentioned were I'm stuck... any help or input would be much appreciated !!

Nzo

 

I'm relatively new to C programming myself, but the trick is to think like a compiler or computer. Run through the code and see what the compiler would do. Also, does your free compiler have a simulator? I know that MPLAB does.

 

Hello electronerd, yes I'm using MPLAB too... I did not know there were simulators... that's good to know. CC5X is just to compile from C code to the pic... and is called automatically from MPLAB.

My problem is how to go from ADRESH the output of the Analog-To-Digital converter... to the PWM... I want ADRESH * P(some gain) = PWM Output on P1A.. Does anyone know how to do this ?

 

Is it possible that you mean the PIC16F690? I don't think the PIC16F9690 exists.

Assuming it's the PIC16F690, what have you found in section 11.0 of the user manual?

 

Hello John, yes you're right it's the PIC16F690.. I've looked at section 11 on the enhenced PWM but still I not able to figure out how to output the results of the DAC i.e. ADRESH through PWM... ? Anyone ?

 

All right, now go down to section 11.3.7, "SETUP FOR PWM OPERATION". What are you seeing there?