formula convertion problem

[dope40]

Hi so i have this formula AFR = V*0.228+0.70 .. Where V is the adc value in volts , but i dont know how to convert it into volts and use it in the formula.

 

[kabeer02]

What do you want to convert to volts?

 

[dope40]

I want to convert ADC_Read value in volts

 

[nick703]

if u using 10 bit ADC then read is between 0 to 1023 right. so 0 is 0V and 1023 is 5v . if configuration is correct. so 2.5v if adc value is 511.5. so put this voltage to your equation .

 

[S.P.S]

Just multiply the adc read value with the step size.V=Stepsize*adc read value (mV)
Step size can be calculated by
step= ADC Vref/2^adc resolution.
if you are using 10bit adc and Adc vref=5V then
step=5/2^10 mV=4.8mV

 

[dope40]

Thanks i figured it out , and now it works , but now i have to figure out how to display it on 3 7-segment displays . For example if i get AFR = 14.7 and break it down to 1, 4, 7 how do i multiplex it on to the 7-segments, so that the first = 1 second = 4 .. etc. ?

 

[jayanth.devarayanadurga]

turn off all digits.
Assign SSD mask equivalent to 1 to SSD data port and turn ON digit1 for 5 ms then turn off all digits.
Assign SSD mask equivalent to 4 to SSD data port and turn ON digit2 for 5 ms then turn off all digits.

repeat continuously

 

[dope40]

How do i assign SSD mask to SSD data port ? :???:

 

[jayanth.devarayanadurga]

What compiler are you using?

https://embedded-lab.com/blog/?p=2086

Common Cathode Masks

0 0x3F
1 0x06
2 0x5B
3 0x4F
4 0x66
5 0x6D
6 0x7D
7 0x07
8 0x7F
9 0x6F

Common Anode Masks

0 0xC0;
1 0xF9;
2 0xA4;
3 0xB0;
4 0x99;
5 0x92;
6 0x82;
7 0xF8;
8 0x80;
9 0x90;

digit[] contains number split and it is char type
CA[] or CC[] contains masks and is also char type

SSDPORT = CA[digit[x]];

 

[dope40]

I am using MikroC

 

[jayanth.devarayanadurga]

Post circuit. We need to know the circuit for writing the code or to help you.

 

[dope40]

Here is the code i have menaged to write so far ....

unsigned short one, two, three ;
unsigned char ch;
unsigned int adc_rd;
long tlong;





void main() {
    INTCON = 0x20;                      // All interrupts disabled
    ANSEL = 0x04;                    // Pin RA2 is configured as an analog input
    TRISA = 0x04;
    ANSELH = 0;                      // Rest of pins are configured as digital
    TRISD = 0;
    TRISE = 0;


    ADCON1 = 0x82;                   // A/D voltage reference is VCC
    TRISA = 0xFF;                    // All port A pins are configured as inputs
    Delay_ms(500);


    while (1) {
      adc_rd = ADC_Read(2);

        tlong = ((5000/1023)*(long)adc_rd)/10   ;
        tlong = (tlong*2)+1000;
        one = tlong / 1000;
        two =  (tlong / 100) % 10;
    }
}

and here is the circuit ......

 

[jayanth.devarayanadurga]

What should it display, Integer or real value? What type of display is used, CC or CA?, The circuit is incomplete. You need NPN/PNP transistors to enable/disable the segments. It can't be guessed from your circuit. Zip and post mikroC project files + Proteus file.

 

[dope40]

Here are the files , i am using NPN transistors , it needs to display the integrated value , the displays are CC.
View attachment Wideband.rar

 

[jayanth.devarayanadurga]

Your circuit is wrong. There is no ADC channel in PIC16F628A. You can't use it to to read Analog values. You mikroC Project file is blank. Change your PIC and post a new circuit.

 

[dope40]

OK, will you recommend which PIC to use for this project.

 

[nick703]

there are lots of pic available to do this project try pic16f877 .

 

[dope40]

how can i multiplex the value on to 3 CC 7-segment displays?

 

[jayanth.devarayanadurga]

Zip and post your project files + Proteus file. I will modify it for 3 digits CC displays.

 

[dope40]

View attachment Wideband.rar Here is the file ... i hope its ok