What's wrong with this sketch?

Projects Programming
1

Hi,
This Arduino Voltmeter With an OLED Display from:

The serial monitor shown 'test' only as long as the input voltage on.

#include "U8glib.h"            // U8glib library for the OLED


int analogInput = A0;  //// was 0;
float vout = 0.0;
float vin = 0.0;
float R1 = 100000.0; // resistance of R1 (100K)
float R2 = 10000.0; // resistance of R2 (10K)
int value = 0;

U8GLIB_SH1106_128X64 u8g(13, 11, 10, 9, 8); // D0=13, D1=11, CS=10, DC=9, Reset=8

void draw(void)
{
  u8g.setFont(u8g_font_profont17r);        // select font
  u8g.drawStr(18, 12, "VOLTAGE");
  u8g.setPrintPos(33, 40);
  u8g.drawRFrame(15, 20, 100, 30, 10);     // draws frame with rounded edges
  u8g.println(vin);                        //Prints the voltage
  u8g.println("V");
}
void setup() {

  Serial.begin(9600);

  Serial.print("File   : "), Serial.println(__FILE__);
  Serial.print("Date   : "), Serial.println(__DATE__);
  delay(1000);

  pinMode(analogInput, INPUT);
}
void loop() {
  // read the value at analog input
  value = analogRead(analogInput);
  vout = (value * 5.0) / 1024.0; // see text
  vin = vout / (R2 / (R1 + R2));
  if (vin < 0.09) {
    vin = 0.0; //statement to quash undesired reading !

    Serial.print("value=");
    Serial.println(value);

    Serial.print("vin=");
    Serial.println(vin); 
    
    delay(500);
  }
  u8g.firstPage();
  do
  {
    draw();
  }
  while ( u8g.nextPage() );

  Serial.println("test");

  delay(500);
}

Serial Monitor:

value=0
vin=0.00
test
value=0
vin=0.00
test
value=0
vin=0.00
test
value=1
vin=0.00
test
value=0
vin=0.00
test
value=1
vin=0.00
test
value=0
vin=0.00
test
value=0
vin=0.00
test
value=0
vin=0.00
test
value=0
vin=0.00
test
value=0
vin=0.00
test
value=0
vin=0.00
test
value=0
vin=0.00
test
test
test
test
test
test
test
test
test
test
test
test

Thanks.
Adam

2

Likely a wiring error.
Paul

1 Like
3

Well, I assume when you connect a voltage it is above 0.09V in which case value and vin will not display on the serial monitor:

  if (vin < 0.09) {
    vin = 0.0; //statement to quash undesired reading !

    Serial.print("value=");
    Serial.println(value);

    Serial.print("vin=");
    Serial.println(vin); 
    
    delay(500);
  }
1 Like
4

Thanks.

5

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