You are offline. Pages you have opened before still work. Flashing and buy links need a connection.

DS18B20 with Wi-Fi portal

The same DS18B20 probe, but Wi-Fi is set from a phone through a captive portal instead of being compiled in.

Starter20 min115200 baud

Board

ESP32

3V3

GND

CMD

CLK

Fig. 1. Pins this project uses on the ESP32-DevKitC V4, 38 pin. USB connector at the bottom.

Wiring

From	To board	Note
DS18B20 red	3V3
DS18B20 black	GND
DS18B20 data, usually yellow	GPIO 4	4.7 kΩ pull-up from data to 3V3

Tested on this board

Not run on this board yet. Treat the wiring and code as a first draft.

Firmware, Arduino sketch for ESP32 Dev Module

/**
 * DS18B20 → ProbeHarbor push ingest with WiFiManager (ESP32 / ESP8266).
 *
 * Libraries: OneWire, DallasTemperature, WiFiManager (tzapu).
 * Set INGEST_URL (Devices download or #define). First boot opens a captive portal
 * AP named "ProbeHarbor-Setup" — join it, enter home Wi‑Fi, reboot.
 *
 * USB Serial 115200 → expect POST 200 after Wi‑Fi is saved.
 */
#include <OneWire.h>
#include <DallasTemperature.h>
#include <WiFiManager.h>

#if defined(ESP32) || defined(ESP8266)
#include <WiFi.h>
#include <HTTPClient.h>
#else
#error "This sample targets ESP32/ESP8266."
#endif

#ifndef INGEST_URL
#define INGEST_URL "https://probeharbor.dev/api/ingest/YOUR_DEVICE_KEY"
#endif

#ifndef ONE_WIRE_PIN
#define ONE_WIRE_PIN 4
#endif

OneWire oneWire(ONE_WIRE_PIN);
DallasTemperature sensors(&oneWire);

const unsigned long INTERVAL_MS = 60UL * 1000UL;
unsigned long lastPost = 0;

void setup() {
  Serial.begin(115200);
  sensors.begin();

  WiFiManager wifiManager;
  // wifiManager.resetSettings(); // uncomment once to clear saved credentials
  wifiManager.setConfigPortalTimeout(180);
  if (!wifiManager.autoConnect("ProbeHarbor-Setup")) {
    Serial.println("WiFi portal timed out — restarting");
    delay(2000);
    ESP.restart();
  }
  Serial.println("WiFi ok");
}

bool postTempF(float tempF) {
  if (WiFi.status() != WL_CONNECTED) return false;
  HTTPClient http;
  http.begin(INGEST_URL);
  http.addHeader("Content-Type", "application/json");
  char body[128];
  snprintf(body, sizeof(body), "{\"temp1\":%.2f,\"rssi\":%d}", tempF, WiFi.RSSI());
  int code = http.POST(body);
  Serial.printf("POST %d %s\n", code, body);
  http.end();
  return code >= 200 && code < 300;
}

void loop() {
  unsigned long now = millis();
  if (now - lastPost < INTERVAL_MS) return;
  lastPost = now;

  sensors.requestTemperatures();
  float c = sensors.getTempCByIndex(0);
  if (c == DEVICE_DISCONNECTED_C) {
    Serial.println("DS18B20 disconnected");
    return;
  }
  float f = c * 9.0f / 5.0f + 32.0f;
  postTempF(f);
}

3V3

GND

3V3

RST

GND

Fig. 1. Pins this project uses on the ESP32-S3-DevKitC-1, 44 pin. USB connector at the bottom.

Wiring

From	To board	Note
DS18B20 red	3V3
DS18B20 black	GND
DS18B20 data, usually yellow	GPIO 4	4.7 kΩ pull-up from data to 3V3

Tested on this board

Not run on this board yet. Treat the wiring and code as a first draft.

Firmware, Arduino sketch for ESP32S3 Dev Module

/**
 * DS18B20 → ProbeHarbor push ingest with WiFiManager (ESP32 / ESP8266).
 *
 * Libraries: OneWire, DallasTemperature, WiFiManager (tzapu).
 * Set INGEST_URL (Devices download or #define). First boot opens a captive portal
 * AP named "ProbeHarbor-Setup" — join it, enter home Wi‑Fi, reboot.
 *
 * USB Serial 115200 → expect POST 200 after Wi‑Fi is saved.
 */
#include <OneWire.h>
#include <DallasTemperature.h>
#include <WiFiManager.h>

#if defined(ESP32) || defined(ESP8266)
#include <WiFi.h>
#include <HTTPClient.h>
#else
#error "This sample targets ESP32/ESP8266."
#endif

#ifndef INGEST_URL
#define INGEST_URL "https://probeharbor.dev/api/ingest/YOUR_DEVICE_KEY"
#endif

#ifndef ONE_WIRE_PIN
#define ONE_WIRE_PIN 4
#endif

OneWire oneWire(ONE_WIRE_PIN);
DallasTemperature sensors(&oneWire);

const unsigned long INTERVAL_MS = 60UL * 1000UL;
unsigned long lastPost = 0;

void setup() {
  Serial.begin(115200);
  sensors.begin();

  WiFiManager wifiManager;
  // wifiManager.resetSettings(); // uncomment once to clear saved credentials
  wifiManager.setConfigPortalTimeout(180);
  if (!wifiManager.autoConnect("ProbeHarbor-Setup")) {
    Serial.println("WiFi portal timed out — restarting");
    delay(2000);
    ESP.restart();
  }
  Serial.println("WiFi ok");
}

bool postTempF(float tempF) {
  if (WiFi.status() != WL_CONNECTED) return false;
  HTTPClient http;
  http.begin(INGEST_URL);
  http.addHeader("Content-Type", "application/json");
  char body[128];
  snprintf(body, sizeof(body), "{\"temp1\":%.2f,\"rssi\":%d}", tempF, WiFi.RSSI());
  int code = http.POST(body);
  Serial.printf("POST %d %s\n", code, body);
  http.end();
  return code >= 200 && code < 300;
}

void loop() {
  unsigned long now = millis();
  if (now - lastPost < INTERVAL_MS) return;
  lastPost = now;

  sensors.requestTemperatures();
  float c = sensors.getTempCByIndex(0);
  if (c == DEVICE_DISCONNECTED_C) {
    Serial.println("DS18B20 disconnected");
    return;
  }
  float f = c * 9.0f / 5.0f + 32.0f;
  postTempF(f);
}

GND

3V3

GND

RST

GND

Fig. 1. Pins this project uses on the ESP32-C3-DevKitM-1, 30 pin. USB connector at the bottom.

Wiring

From	To board	Note
DS18B20 red	3V3
DS18B20 black	GND
DS18B20 data, usually yellow	GPIO 4	4.7 kΩ pull-up from data to 3V3

Tested on this board

Not run on this board yet. Treat the wiring and code as a first draft.

Firmware, Arduino sketch for ESP32C3 Dev Module

/**
 * DS18B20 → ProbeHarbor push ingest with WiFiManager (ESP32 / ESP8266).
 *
 * Libraries: OneWire, DallasTemperature, WiFiManager (tzapu).
 * Set INGEST_URL (Devices download or #define). First boot opens a captive portal
 * AP named "ProbeHarbor-Setup" — join it, enter home Wi‑Fi, reboot.
 *
 * USB Serial 115200 → expect POST 200 after Wi‑Fi is saved.
 */
#include <OneWire.h>
#include <DallasTemperature.h>
#include <WiFiManager.h>

#if defined(ESP32) || defined(ESP8266)
#include <WiFi.h>
#include <HTTPClient.h>
#else
#error "This sample targets ESP32/ESP8266."
#endif

#ifndef INGEST_URL
#define INGEST_URL "https://probeharbor.dev/api/ingest/YOUR_DEVICE_KEY"
#endif

#ifndef ONE_WIRE_PIN
#define ONE_WIRE_PIN 4
#endif

OneWire oneWire(ONE_WIRE_PIN);
DallasTemperature sensors(&oneWire);

const unsigned long INTERVAL_MS = 60UL * 1000UL;
unsigned long lastPost = 0;

void setup() {
  Serial.begin(115200);
  sensors.begin();

  WiFiManager wifiManager;
  // wifiManager.resetSettings(); // uncomment once to clear saved credentials
  wifiManager.setConfigPortalTimeout(180);
  if (!wifiManager.autoConnect("ProbeHarbor-Setup")) {
    Serial.println("WiFi portal timed out — restarting");
    delay(2000);
    ESP.restart();
  }
  Serial.println("WiFi ok");
}

bool postTempF(float tempF) {
  if (WiFi.status() != WL_CONNECTED) return false;
  HTTPClient http;
  http.begin(INGEST_URL);
  http.addHeader("Content-Type", "application/json");
  char body[128];
  snprintf(body, sizeof(body), "{\"temp1\":%.2f,\"rssi\":%d}", tempF, WiFi.RSSI());
  int code = http.POST(body);
  Serial.printf("POST %d %s\n", code, body);
  http.end();
  return code >= 200 && code < 300;
}

void loop() {
  unsigned long now = millis();
  if (now - lastPost < INTERVAL_MS) return;
  lastPost = now;

  sensors.requestTemperatures();
  float c = sensors.getTempCByIndex(0);
  if (c == DEVICE_DISCONNECTED_C) {
    Serial.println("DS18B20 disconnected");
    return;
  }
  float f = c * 9.0f / 5.0f + 32.0f;
  postTempF(f);
}

Parts

Quantity	Part	Where to buy
1×	ESP32 dev board	Buy at Amazon
1×	DS18B20 waterproof probe	Buy at Adafruit
1×	4.7 kΩ resistor	Buy at Amazon

Amazon buy links may include an Associates tag, and this site may earn a commission from qualifying Amazon purchases at no extra cost to you. Adafruit links are direct.

Libraries

OneWire, DallasTemperature, WiFiManager (tzapu)

Load it

In the Arduino IDE, install the esp32 board package and pick the board named above the sketch.
Install the libraries listed above from the Library Manager.
Paste the sketch, choose the board's port and upload. Hold BOOT if the upload stalls at Connecting.
Close the IDE's serial monitor, then open the bench here to watch the output.

Sketch source on GitHub

Field notes

Set INGEST_URL at the top of the sketch. Wi-Fi is not compiled in.
On first boot, join the ProbeHarbor-Setup network from a phone, enter your home Wi-Fi and let the board restart.

Open the bench at 115200 baud