Hilitchi DS18B20 not recognized by ESP LoRa 32 V3.2

#1

I’ve been trying for several days to get my Hilitchi DS18B20 to be recognized by my ESP V3.2 board with no luck.

Here are the libraries and versions I currently have installed:

  • OneWire: 2.3
  • DallasTemperature: 4.0.3
  • Heltec ESP32 Dev-Boards: 2.1.4
  • Adafruit BME280 Library: 2.3.0
  • Adafruit BusIO: 1.17.2
  • Adafruit GFX Library: 1.12.1
  • Adafruit Unified Sensor: 1.1.15
  • OneWireNg: 0.14.0
  • U8g2: 2.35.30

Here is my simple code that I’m using to just try to read from the sensor:

#include "LoRaWan_APP.h"            // LoRa driver for Heltec boards
#include "Arduino.h"
#include <OneWire.h>                // For 1-Wire communication with DS18B20
#include <DallasTemperature.h>      // DS18B20 temperature sensor library

// ===============================
// DS18B20 Temperature Sensor Setup
// ===============================

#define ONE_WIRE_BUS 7              // GPIO pin connected to DS18B20 data line
OneWire oneWire(ONE_WIRE_BUS);     // Create OneWire instance
DallasTemperature sensors(&oneWire); // Pass OneWire to Dallas library

void setup() {
  Serial.begin(115200);
  Serial.println("DS18B20 Test with Heltec Board Library");

  // Initialize MCU and peripherals (Heltec board specifics)
  Mcu.begin(HELTEC_BOARD, SLOW_CLK_TPYE);

  // Initialize the temperature sensor
  sensors.begin();
  Serial.println("DS18B20 initialized");
  
  // Debug: Check device count
  Serial.print("Number of devices found: ");
  Serial.println(sensors.getDeviceCount());
}

void loop() {
  Serial.println("Requesting temperatures...");
  sensors.requestTemperatures(); 
  delay(750); // Wait for conversion to complete
  
  Serial.println("Getting temperature...");
  float temperatureC = sensors.getTempCByIndex(0);
  float temperatureF = sensors.getTempFByIndex(0);
  
  Serial.print("Raw C value: ");
  Serial.println(temperatureC);
  Serial.print("Raw F value: ");
  Serial.println(temperatureF);
  
  if (temperatureC == DEVICE_DISCONNECTED_C) {
Serial.println("ERROR: Device disconnected!");
  } else if (temperatureC == -127.00) {
Serial.println("ERROR: Invalid reading!");
  } else {
Serial.print(temperatureC);
Serial.println("ºC");
Serial.print(temperatureF);
Serial.println("ºF");
  }
  
  delay(5000);
}

My Serial Monitor reports this when I run this code with the sensor hooked up:

ESP-ROM:esp32s3-20210327
Build:Mar 27 2021
rst:0x1 (POWERON),boot:0x2b (SPI_FAST_FLASH_BOOT)
SPIWP:0xee
mode:DIO, clock div:1
load:0x3fce3818,len:0x508
load:0x403c9700,len:0x4
load:0x403c9704,len:0xad0
load:0x403cc700,len:0x29e4
entry 0x403c9880
DS18B20 Test with Heltec Board Library
DS18B20 initialized
Number of devices found: 0
Requesting temperatures...
Getting temperature...
Raw C value: -127.00
Raw F value: -196.60
ERROR: Device disconnected!

Any help would be greatly appreciated, I’m lost at this point.

#2

Two questions then:

  1. How are you powering the sensor? 3V3 or Ve pin? 3V3 should be OK, but Ve will need to be turned ON.
  2. Are you sure you’ve connected the sensor to GPIO7 (pin 18 on the J3 header)?

If you’re sure about both of those, then I’d cut things back to the bare essentials—get rid of the LoRaWan_APP library and the Mcu.begin call, neither of those should be required to read the DS18B20 sensor.

If you’re still having trouble, it might be the OneWire library. I’ve had trouble with compatibility there when switching between CubeCell and ESP32 boards—the two actually use different versions of the OneWire library. I have rectified that particular problem in the version of the library that I use but I don’t have a V3.2 board to test this. I do, however, run V3 (probably V3.0) boards with DS18B20 sensors without any problems (even without the OneWire library modification).