VOLTMETER with PIC 16F877A

Khaderah · Apr 27, 2012

One of the projects

https://www.hlektronika.gr/forum/showthread.php?t=62966

Tahmid · Apr 27, 2012

babatundeawe said:
hi everyone good post here. please how can i measure a negative voltage with the pic. for instance i want to measure frm -12 to 0 to 12v

You can use a circuit that detects whether the input is +ve or -ve. Then, use a differential amplifier with unity gain to read the "magnitude" of the input voltage. This is one of many possible circuits.

Hope this helps.
Tahmid.

Khaderah · Apr 28, 2012

You can use https://www.analog.com/static/imported-files/data_sheets/AD628.pdf

Khaderah · May 3, 2012

negative voltage circuit (Elektor)

**broken link removed**

tpetar · May 3, 2012

sahu said:
how can calculate it ? , means equation =?

PIC16F877 have 8 channels with 10-bit. That means 2^10 = 1024. 1023 steps in 5V - 5/1023= 0,0048V (4,8mV) per step.

For ADC 12-bit:
2^12 = 4096 steps in 5V. 5/4095 = 0,0012V (1,2mV) per step.

We have 8-bit, 10-bit, 12-bit, 16-bit, 18-bit, 24-bit ADCs.

Khaderah · May 29, 2012

**broken link removed**

4s7ww · Jun 23, 2012

dear Tahmid

can you please show me how to modify this code t (pic16f877a voltmeter) to measure two voltages, using pins ra1, ra2
wasantha(4s7ww)
thanks...

ahmed mesbah · Jun 26, 2012

i dont under stand
why you adding 48 ???
all of you added 48 on the value that will be on the lcd???
whyy
i dont under stand this
i am a beganner

Jestin_cubetech · Jun 26, 2012

Float value display on LCD - Simple method

Code:

----------------------------------------------------------------------------
float  value=5.0005;    //float value 
int tmp1,tmp2;

tmp1=(int)value;             // tmp1=5            //display tmp  5  on lcd 
value=value-(float)tmp1;   //value=0.0005
value+=1;                     // value = 1.0005   
value=value*10000;           10005
                                                //display '.' in lcd 
tmp2=(int)value;
                                             //display tmp2   4 digit on lcd , avoid  MSB value 1    
----------------------------------------------------------------------------

Tahmid · Jun 27, 2012

ahmed mesbah said:
i dont under stand
why you adding 48 ???
all of you added 48 on the value that will be on the lcd???
whyy
i dont under stand this
i am a beganner

To display a character on the LCD, the corresponding ASCII value must be sent.

Here is an ASCII chart: **broken link removed**
**broken link removed**

As you can see, for 0 to 9, the ASCII values are 48 greater than the character value. So, ASCII value of 0 is 48, of 1 is 49, of 2 is 50 and so on. That's why 48 is added.

Hope this helps.
Tahmid

- - - Updated - - -

4s7ww said:
dear Tahmid

can you please show me how to modify this code t (pic16f877a voltmeter) to measure two voltages, using pins ra1, ra2
wasantha(4s7ww)
thanks...

You will need to use the ADC channels corresponding to RA1 and RA2 which would be AN1 and AN2. Take reading from AN1, do the processing and display it on the LCD. Then take reading from AN2, do the processing and display it on the LCD.

jayanthd · Jun 28, 2012

Why do you need source code for FloatToStr Library?

Check the post 7 @ https://www.edaboard.com/threads/63677/

manish26264 · Feb 1, 2013

Hi All,
This is my first post, I am new to micro controllers, have made a multi channel voltmeter using 16F877A and microcosm pro. I would like to eliminate leading zeros, i.e. my vm is 0 to 400 V, when measuring 50 V the display must be 50.0 instead of 0500.0. Can I get any suggestion .

iukhan · Feb 1, 2013

manish26264 said:
Hi All,
This is my first post, I am new to micro controllers, have made a multi channel voltmeter using 16F877A and microcosm pro. I would like to eliminate leading zeros, i.e. my vm is 0 to 400 V, when measuring 50 V the display must be 50.0 instead of 0500.0. Can I get any suggestion .

Post relavent code, for suggestion.

manish26264 · Feb 2, 2013

Many Thanks lijoppans, I will try to implement in my code.

Hi iukhan,

My Code is as below:

// LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections

unsigned int value;
unsigned char car,x,y;
char *voltage = "000.0";
long temp;

void ShowVoltage (int x,int y, unsigned int value) // Routine to show the ADC_read conversion in Volt
{
temp = (long)value* 50 * 80;
temp = (temp / 1023);

voltage[0] = (temp/1000)%10 + 48;
voltage[1] = (temp/100)%10 + 48;
voltage[2] = (temp/10)%10 + 48;
voltage[4] = temp % 10 + 48;
Lcd_Out (x,y,voltage);
delay_ms(10);
}

void main() {

ADCON1 = 0x80; // All analogs - right justify
TRISA = 0xFF; // PORTA Input
TRISB = 0; // PORTB Output

Lcd_Init();
Lcd_Cmd(_LCD_CLEAR);
Lcd_Cmd(_LCD_CURSOR_OFF);

do {
value = ADC_Read(1); // channel 1 (RA1)
Lcd_Out(1,1,"Ch1:");
ShowVoltage(1,6,value);
} while(1);
}

iukhan · Feb 2, 2013

manish26264 said:
My Code is as below:

Add the following code in ShowVoltage() function [before Lcd_Out (x,y,voltage); statement]

Code:

......
voltage[4] = temp % 10 + 48;

if (voltage[0]==48){
   voltage[0]=32;
   if(voltage[1]==48) voltage[1]=32;
}
Lcd_Out (x,y,voltage);
.....

manish26264 · Feb 2, 2013

iukhan said:
Add the following code in ShowVoltage() function [before Lcd_Out (x,y,voltage); statement]

Code:

...... voltage[4] = temp % 10 + 48; if (voltage[0]==48){ voltage[0]=32; if(voltage[1]==48) voltage[1]=32; } Lcd_Out (x,y,voltage); .....

Many thanks iukhan, this works like charm.

manish26264 · Feb 13, 2013

Hi all,
One of the two volts reading is fluctuating too much, I am using 16F877A for measuring AC volts. I have used step down transformer 400 : 5 V and a10k preset to further reduce to 2 V, which is fed to precision rectifier using 2 lm301, this reading is fluctuating while in other I have used resistive divider and have reduced the measuring volts to 400mV, this is also fed to similar precision rectifier but this reading does not fluctuate. I have used 100 nf capacitors after precision rectifiers and also on power supply pins of micro. Please suggest how to eliminate the fluctuations

tpetar · Feb 13, 2013

Add 1uF - 2,2uF close to ADC input, before 5,1V zener.

manish26264 · Feb 13, 2013

Many thanks for such fast reply, will try it and come back soon.

tpetar · Feb 13, 2013

You can use small Tantal capacitor with adequate voltage ratings (>10V).

VOLTMETER with PIC 16F877A

Junior Member level 3

Advanced Member level 6

Junior Member level 3

Junior Member level 3

Attachments

Advanced Member level 7

Junior Member level 3

Attachments

Newbie level 1

Newbie level 1

Advanced Member level 1

Advanced Member level 6

Banned

Newbie level 6

Advanced Member level 4

Newbie level 6

Advanced Member level 4

Newbie level 6

Newbie level 6

Advanced Member level 7

Newbie level 6

Advanced Member level 7

Similar threads

Privacy & Transparency

Privacy & Transparency