[Solved] Analog Pin 2 reacting but nothing connected.

Projects Programming
1

I haven't received my pas sensor yet (Peddle Assist Sensor) and so have left the pin not connected, however for some reason, when I operate the trigger on AnalogPin 3 the value increases for AnalogPin 2
Here is my code:

/*********************************************************************
This is a direct hack of adafruits ssd1306*64 i2c file
Todo
Add PAS (Pedal Assist Sensor) control code
Actual Motor output to Motpin
*********************************************************************/

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

/* HAll503 Config */ 
int ThrotPin = 3; // Throttle Hall Sensor
int Th = '0';       // Variable th stores reading from HALL503
/* End of HAll503 Config */ 
int Motpin = 9; // PWM output pin for brused motor control.
/* Motor Control */
int PasPin = 2; // PAS Pin
int Pas = '0';
/* PAS Sensor */

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define NUMFLAKES 10
#define XPOS 0
#define YPOS 1
#define DELTAY 2


#define LOGO16_GLCD_HEIGHT 16 
#define LOGO16_GLCD_WIDTH  16 
static const unsigned char PROGMEM logo16_glcd_bmp[] =
{ B00000011, B11000000,
  B00001100, B00110000,
  B00010000, B00001000,
  B00100000, B00000100,
  B01000100, B00000010,
  B01000100, B00000010,
  B10000100, B00000001,
  B10000010, B00000001,
  B10000010, B00000001,
  B10000010, B00000001,
  B01000000, B00000010,
  B01000001, B10000010,
  B00100011, B11000100,
  B00010000, B00001000,
  B00001100, B00110000,
  B00000011, B11000000, };

#if (SSD1306_LCDHEIGHT != 64)
#error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif

void setup()   {                
  Serial.begin(9600); // Only for debugging.

  // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr 0x3D (for the 128x64)
  // init done
}


void loop() 
{
  display.clearDisplay();
  display.drawBitmap(1, 1,  logo16_glcd_bmp, 16, 16, 1);
  // text display tests
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(20,0);
  Th = analogRead(ThrotPin);     // read the input pin
  Serial.println(Th);             //Prints to Serial terminal
  display.println(Th);            //Prints to display
  display.setCursor(0,20);
  Pas = analogRead(PasPin);
  display.println(Pas); 
  display.display();
  delay(10);
  // analogWrite(Motpin, Th / 4); // Analogue read is 0-1024, Analogue write is 0-256
}


void testdrawbitmap(const uint8_t *bitmap, uint8_t w, uint8_t h) {
  uint8_t icons[NUMFLAKES][3];
  }



void testdrawchar(void) {
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);

  for (uint8_t i=0; i < 168; i++) {
    if (i == '\n') continue;
    display.write(i);
    if ((i > 0) && (i % 21 == 0))
      display.println();
  }    
  display.display();
}

Is this a coding error or a hardware issue?

3

Delta_G:
It's a misunderstanding on your part of how an unconnected pin should act. It isn't connected to anything so what voltage should it read?

Google "Floating Input"

Ahh so it is picking up the signal from pin 3.
Ah, ok, my mistake. I was expecting a random reading, not one directly connected to the pin next door.

Thanks for the clarification.