Documentation

// 49E Linear Hall Effect Sensor - Arduino Example
// OUT -> A0, VCC -> 5V, GND -> GND

const int hallPin = A0;
const float MV_PER_GAUSS = 1.4;   // ~1.4 mV/G at 5V supply
float zeroVolts = 2.5;

float readVolts(int samples) {
  long total = 0;
  for (int i = 0; i < samples; i++) {
    total += analogRead(hallPin);
    delay(2);
  }
  return (total / (float)samples) * (5.0 / 1023.0);
}

void setup() {
  Serial.begin(9600);
  Serial.println("Calibrating - keep magnets away...");
  delay(1000);
  zeroVolts = readVolts(200);
  Serial.print("Zero point: ");
  Serial.print(zeroVolts, 3);
  Serial.println(" V. Bring a magnet close!");
}

void loop() {
  float volts = readVolts(20);
  float gauss = (volts - zeroVolts) * 1000.0 / MV_PER_GAUSS;

  Serial.print("OUT: ");
  Serial.print(volts, 3);
  Serial.print(" V | ~");
  Serial.print(gauss, 0);
  Serial.print(" G ");

  if (gauss > 15)       Serial.println("(south pole)");
  else if (gauss < -15) Serial.println("(north pole)");
  else                  Serial.println("(no field)");

  delay(300);
}

# 49E Linear Hall Effect Sensor - ESP32 MicroPython Example
# OUT -> GPIO 34, VCC -> 3V3, GND -> GND

from machine import ADC, Pin
import time

adc = ADC(Pin(34))
adc.atten(ADC.ATTN_11DB)      # full 0-3.3V range

MV_PER_GAUSS = 0.9            # ratiometric: ~0.9 mV/G at 3.3V supply

def read_volts(samples):
    total = 0
    for _ in range(samples):
        total += adc.read_uv()
        time.sleep_ms(2)
    return total / samples / 1_000_000

print("Calibrating - keep magnets away...")
time.sleep(1)
zero = read_volts(200)
print("Zero point: {:.3f} V. Bring a magnet close!".format(zero))

while True:
    volts = read_volts(20)
    gauss = (volts - zero) * 1000 / MV_PER_GAUSS

    if gauss > 15:
        pole = "south pole"
    elif gauss < -15:
        pole = "north pole"
    else:
        pole = "no field"

    print("OUT: {:.3f} V | ~{:.0f} G ({})".format(volts, gauss, pole))
    time.sleep(0.3)

#!/usr/bin/env python3
# 49E Linear Hall Effect Sensor - Raspberry Pi + ADS1115 Example
# OUT -> ADS1115 A0, SDA/SCL -> GPIO 2/3, VCC -> 3.3V
# Install: pip3 install adafruit-circuitpython-ads1x15

import time
import board
import busio
import adafruit_ads1x15.ads1115 as ADS
from adafruit_ads1x15.analog_in import AnalogIn

MV_PER_GAUSS = 0.9   # ~0.9 mV/G at 3.3V supply

i2c = busio.I2C(board.SCL, board.SDA)
ads = ADS.ADS1115(i2c)
ads.gain = 1
channel = AnalogIn(ads, ADS.P0)

def read_volts(samples):
    total = 0.0
    for _ in range(samples):
        total += channel.voltage
        time.sleep(0.002)
    return total / samples

print("Calibrating - keep magnets away...")
time.sleep(1)
zero = read_volts(100)
print("Zero point: {:.3f} V. Bring a magnet close!".format(zero))

try:
    while True:
        volts = read_volts(20)
        gauss = (volts - zero) * 1000 / MV_PER_GAUSS

        if gauss > 15:
            pole = "south pole"
        elif gauss < -15:
            pole = "north pole"
        else:
            pole = "no field"

        print("OUT: {:.3f} V | ~{:.0f} G ({})".format(volts, gauss, pole))
        time.sleep(0.3)
except KeyboardInterrupt:
    print("Stopped by user")

# 49E Linear Hall Effect Sensor - Pico MicroPython Example
# OUT -> GP26 (ADC0), VCC -> 3V3(OUT), GND -> GND

from machine import ADC
import time

adc = ADC(26)
CONVERSION = 3.3 / 65535
MV_PER_GAUSS = 0.9        # ~0.9 mV/G at 3.3V supply

def read_volts(samples):
    total = 0
    for _ in range(samples):
        total += adc.read_u16()
        time.sleep_ms(2)
    return total / samples * CONVERSION

print("Calibrating - keep magnets away...")
time.sleep(1)
zero = read_volts(200)
print("Zero point: {:.3f} V. Bring a magnet close!".format(zero))

while True:
    volts = read_volts(20)
    gauss = (volts - zero) * 1000 / MV_PER_GAUSS

    if gauss > 15:
        pole = "south pole"
    elif gauss < -15:
        pole = "north pole"
    else:
        pole = "no field"

    print("OUT: {:.3f} V | ~{:.0f} G ({})".format(volts, gauss, pole))
    time.sleep(0.3)