current control using potentiometer

[stereo]

here are my programming. this is a programme that read the voltage(max voltage 5v microcontroller) from analog to digital on the LCD screen.

by using potentiometer, the value can be adjusted to 1024(max) on the lcd. and it is = to 5v.

i really appreciate if someone could help me with this.

>instead of displaying in binary, can i display 5v?

>i would like to add on the value of current max 6A. so on the screen there will be two value. by adjusting the potentiometer to the max, there will be 5v and 6A.




thank you


im using mplab c18 and pic 18f4520


#include <p18f4520.h>
#include <delays.h>
#include <stdlib.h>
int result;
void Init_LCD(void);

void W_ctr_4bit(char);
void w_data_4bit(char);

#define LCD_DATA PORTD
#define LCD_RW
#define LCD_RS
#define LCD_E

unsigned char LCD_TEMP, i;
char MESS[11]= "convertion";
char MESS2[4]= " ";

void InterruptHandlerLow(void);
routine
#pragma code InterruptVectorLow= 0x018
void InterruptVectorLow(void) {
_asm
goto InterruptHandlerLow
routine
_endasm
}
#pragma code
#pragma interruptlow InterruptHandlerLow
void InterruptHandlerLow()
{
if(PIR1bits.TMR1IF){
Delay10TCYx(1);
ADCON0bits.GO=1;
while(ADCON0.bits.DONE);
result= ADRESH*256+ADRESL;
//result>>=4;
PORTB=result;
W_ctr_4bit(0xc0);
for(i=0; i<4;i++)
{W_data_4bit(MESS2);
}
W_ctr_4bit(0xc0);
itoa(result,MESS);
i=0;
while(MESS)
{
W_data_4bit(MESS);
i++;}
TMR1H=0x0b;
TMR1L=0xdc;
PIR1bits.TMR1IF=0;
}
}
void main()
{
TRISD=0;
TRISA=0b11110001;
TRISB=0b11110000;
ADCON0=0b00000001;
ADCON1=0b00001110;
ADCON2=0b10000100;

INTCONbits.GIE=0;
Init_LCD();
for(i=o;i<10;i++)
{
W_data_4bit(MESS);
}
PORTB=0b00000110;
RCONbots.IPEN=1;
IPR1bits.TMR1IP=0;
TMR1H=0x0b;
TMR1L=0xdc;
T1CON=0b11110001;
PIR1bits.TMR1IF=0;
PIR1bits.TMR1IE=1;
INCONbits.GIEL=1;
INCONbits.GIE=1;
while(1);
}
void Init_LCD()
{
Delay1kTCYx(15);
W_ctr_4bit(0x03);
Delay1kTCYx(5);
W_ctr_4bit(0x02);
W_ctr_4bit(0b00101000);
W_ctr_4bit(0b00001100);
W_ctr_4bit(0b00000110);
W_ctr_4bit(0b00000001);
}
void W_ctr_4bit(char x)
{
LCD_RW=0;
LCD_RS=0;
LCD_TEMP=x;
LCD_TEMP>>=4;
LCD_E=1;
LCD_DATA=LCD_TEMP;
Delay1KTCYx(1);
LCD_E=0;
Delay1KTCYx(1);
LCD_TEMP=x;
LCD_TEMP &=0x0f;
LCD_E=1;
LCD_DATA=LCD_TEMP;
Delay1KTCYx(1);
LCD_E=0;
Delay1KTCYx(1)
}


void W_ctr_4bit(char x)
{
LCD_RW=0;
LCD_RS=1;
LCD_TEMP=x;
LCD_TEMP>>=4;
LCD_E=1;
LCD_DATA=LCD_TEMP;
Delay1KTCYx(1);
LCD_E=0;
Delay1KTCYx(1);
LCD_TEMP=x;
LCD_TEMP &=0x0f;
LCD_E=1;
LCD_DATA=LCD_TEMP;
Delay1KTCYx(1);
LCD_E=0;
Delay1KTCYx(1)
}

 

[vijay s]

i thing you asking for how to convert the voltage in binary to actual voltage to display

refvoltage=5v , resolution= 10bit = 1024 steps
single step resolution = 5/1024 = 4.88mv

so each step size indicates 4.88mv

if you have 1024 as your value then 1024*4.88 = 5

this is the thing you have to displat

 

[stereo]

alright noted. so from the code, where should i change? ive tried modify it at
result= ADRESH*256+ADRESL to
result= ADRESH*256+ADRESL/205

and it doesnt make any different. still display in binary.

 

[vijay s]

result= ADRESH*256+ADRESL/205

that is not 205... it should be 5/1024

int temp,result;

temp   = (ADRESH * 256) + ADRESL;       //Make as 16-bit WORD
result  =  (5/1024) * temp;

still the result is in HEX Code.. to display in LCD you have to convert it to ASCII...

your compiler might be having library routine to convert HEX to ASCII.. convert and display

reply what compiler u are using...

__
click helped button if this helps u

 

[kender]

int temp,result;
result  =  (5/1024) * temp;

Not to be nitpicky, but I suspect that result will always be zero, because integer division 5/1024 is always zero. If that ends up being the case, try:

result  =  (5 * temp) / 1024;

 

[stereo]

alright.
result = (5 * temp) / 1024; will display not in binary anymore. it display from 0 to 4. Thnx kender!

ok...how can i put decimal point to make it more accurate? currently, the max it shows only 4 which i believed it should be 4.8++ close to 5.

thnx

 

[vijay s]

multiply with 100 and add decimal point

result = result * 100;

and add decimal point before two decimal value

i hope this work...

 

[stereo]

ok ive tried put the value in both line.
still it didnt show any different.


PORTB=result*100;
or
result= ADRESH*256+ADR*100;
so where should i alter?

 

[vijay s]

result  =  (5 * temp) / 1024;

with this result in HEX use

unsigned char Buf[6];
result = result * 100;
uitoa(result,Buf);          //This converts HEX to ASCII

Now if ur maximum result will be like 488


it will be stored as Buf[0] = 4,Buf[1] = 8, Buf[2] = 8

before displaying this in LCD add decimal point after Buf[0]

 

[stereo]

alright!!! almost got it. i can now adjust untill almost 5v. but theres 1 problem. the highest i could go is 499v without the decimal. supposedly 4.99v.

here's my latest program;


include <p18f4520.h>
#include <delays.h>
#include <stdlib.h>
float result;
void Init_LCD(void);

void W_ctr_4bit(char);
void W_data_4bit(char);

#define LCD_DATA PORTD
#define LCD_RW PORTAbits.RA2
#define LCD_RS PORTAbits.RA3
#define LCD_E PORTAbits.RA1

unsigned char LCD_TEMP, i;
char MESS[16]= "VOLTAGE CONTROL";
char MESS2[10]= " . v 0.6A";
unsigned char Buf[6];

void InterruptHandlerLow(void);
float temp,result;
#pragma code InterruptVectorLow= 0x018
void InterruptVectorLow(void) {
_asm
goto InterruptHandlerLow

_endasm
}
#pragma code
#pragma interruptlow InterruptHandlerLow
void InterruptHandlerLow()
{
if(PIR1bits.TMR1IF){
Delay10TCYx(1);
ADCON0bits.GO=1;
while(ADCON0bits.DONE);

temp = (ADRESH * 256) + ADRESL; //Make as 16-bit WORD
result = (5 * temp) / 1024;
result = result*100 ;

//result>>=4;
PORTB=result;
W_ctr_4bit(0xc0);
for(i=0; i<9; i++)
{W_data_4bit(MESS2);
}
W_ctr_4bit(0xc0);
itoa(result,MESS);
i=0;
while(MESS)
{
W_data_4bit(MESS);
i++;}
TMR1H=0x0b;
TMR1L=0xdc;
PIR1bits.TMR1IF=0;
}
}
void main()
{
TRISD=0;
TRISA=0b11110001;
TRISB=0b11110000;
ADCON0=0b00000001;
ADCON1=0b00001110;
ADCON2=0b10000100;

INTCONbits.GIE=0;
Init_LCD();
for(i=0;i<15;i++)
{
W_data_4bit(MESS);
}
PORTB=0b00000110;
RCONbits.IPEN=1;
IPR1bits.TMR1IP=0;
TMR1H=0x0b;
TMR1L=0xdc;
T1CON=0b11110001;
PIR1bits.TMR1IF=0;
PIE1bits.TMR1IE=1;
INTCONbits.GIEL=1;
INTCONbits.GIE=1;
while(1);
}
void Init_LCD()
{
Delay1KTCYx(15);
W_ctr_4bit(0x03);
Delay1KTCYx(5);
W_ctr_4bit(0x02);
W_ctr_4bit(0b00101000);
W_ctr_4bit(0b00001100);
W_ctr_4bit(0b00000110);
W_ctr_4bit(0b00000001);
}
void W_ctr_4bit(char x)
{
LCD_RW=0;
LCD_RS=0;
LCD_TEMP=x;
LCD_TEMP>>=4;
LCD_E=1;
LCD_DATA=LCD_TEMP;
Delay1KTCYx(1);
LCD_E=0;
Delay1KTCYx(1);
LCD_TEMP=x;
LCD_TEMP &=0x0f;
LCD_E=1;
LCD_DATA=LCD_TEMP;
Delay1KTCYx(1);
LCD_E=0;
Delay1KTCYx(1);
}


void W_data_4bit(char x)
{
LCD_RW=0;
LCD_RS=1;
LCD_TEMP=x;
LCD_TEMP>>=4;
LCD_E=1;
LCD_DATA=LCD_TEMP;
Delay1KTCYx(1);
LCD_E=0;
Delay1KTCYx(1);
LCD_TEMP=x;
LCD_TEMP &=0x0f;
LCD_E=1;
LCD_DATA=LCD_TEMP;
Delay1KTCYx(1);
LCD_E=0;
Delay1KTCYx(1);
}


thnx!

 

[vijay s]

i don't find time to read this program...

u need any help with this...

 

[stereo]

ok that program could only display 499v max.(supposedly 4.99v)

>before displaying this in LCD add decimal point after Buf[0]


where exactly can i put th decimal point?

 

[vijay s]

where exactly can i put the decimal point?

in Main routine you are sending the LCD data byte by byte.. after sending Buf[0] send '.' followed by remaining character....

That program could only display 499v max

the problem might be with arithmetic calculation. 0.01% error is acceptable one

 

[stereo]

im still trying to display with decimal point. what a noob i am.

don't mind the voltage now.

ok with some calculation, i would like to display the current as well.
(the amount of voltage displayed / 0.01ohm resistance)

when i adjust the potentiometer, both (voltage and current) will change.
i've tried edit the program in many ways but still couldnt achieved it.
your expertise is well apreciated.