Integrations

ESPGeiger exposes radiation data through several channels (MQTT, Webhook, JSON endpoint). This page shows how to connect these to common monitoring and automation platforms.

JSON Endpoint

The built-in web server exposes a JSON endpoint at /json:

http://192.168.1.100/json

Response:

{"u":"0T01:23:45","ut":5025,"c":42.00,"s":0.28,"c5":41.50,"c15":40.90,"cs":0.70,"r":151.0,"tc":9876,"mem":19088,"rssi":-45,"tick":712,"t_max":8012,"lps":59831}

Field	Description
u	Uptime string
ut	Uptime in seconds
c	Current CPM
s	Current μSv/h
c5	5-minute smoothed CPM
c15	15-minute smoothed CPM
cs	Current CPS
r	μSv conversion ratio
tc	Total clicks since boot
mem	Free heap memory in bytes
rssi	WiFi signal strength in dBm
hv	HV reading in volts (ESPGeiger-HW only)
tick	EMA-smoothed duration of the 1-second tick callback in microseconds (sTickerCB cost). Typical load indicator; α = 1/8 so single-tick spikes (MQTT publish, etc.) are averaged out. Lower is better.
t_max	Peak tick observed in the current 60-tick window (rolling reset). Use alongside tick to see worst-case cost.
lps	Loop iterations counted in the last second.

GeigerLog

GeigerLog is a free cross-platform log/plot tool for Geiger counters. ESPGeiger exposes a GeigerLog-compatible endpoint at /lastdata that works with GeigerLog’s built-in WiFiClient device.

Configure GeigerLog

1. In GeigerLog open Device → WiFiClient → Config WiFiClient Device.
2. Set the IP address and port to the ESPGeiger device (port 80).
3. Point the data URL at /lastdata.
4. Save, then connect the WiFiClient device.

The /lastdata endpoint returns a single comma-separated line matching the GeigerLog WiFiClient format:

22.50, 0.37, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan

The first two values are the current CPM and CPS. The remaining ten fields are reported as nan — GeigerLog ignores them and plots only the two populated variables.

Notes

• Polling is driven by GeigerLog — ESPGeiger responds on each request, so cadence is whatever you configure on the GeigerLog side.
• The endpoint is always available; there is no toggle in the ESPGeiger portal.
• If you need richer data (5-minute or 15-minute CPM, HV, memory, RSSI) consume /json instead from your own tooling.

Prometheus via Telegraf

Telegraf can poll the JSON endpoint and expose the values as Prometheus metrics:

# telegraf.conf

[[inputs.http]]
  urls = ["http://192.168.1.100/json"]
  method = "GET"
  timeout = "5s"
  data_format = "json_v2"
  name_override = "espgeiger"
  [[inputs.http.tags]]
    device = "espgeiger-xxxxxx"
  [[inputs.http.json_v2]]
    [[inputs.http.json_v2.field]]
      path = "c"
      rename = "cpm"
      type = "float"
    [[inputs.http.json_v2.field]]
      path = "s"
      rename = "usv_h"
      type = "float"
    [[inputs.http.json_v2.field]]
      path = "c5"
      rename = "cpm5"
      type = "float"
    [[inputs.http.json_v2.field]]
      path = "c15"
      rename = "cpm15"
      type = "float"
    [[inputs.http.json_v2.field]]
      path = "cs"
      rename = "cps"
      type = "float"
    [[inputs.http.json_v2.field]]
      path = "tc"
      rename = "total_clicks"
      type = "int"
    [[inputs.http.json_v2.field]]
      path = "ut"
      rename = "uptime_seconds"
      type = "int"
    [[inputs.http.json_v2.field]]
      path = "mem"
      rename = "free_heap"
      type = "int"
    [[inputs.http.json_v2.field]]
      path = "rssi"
      rename = "wifi_rssi"
      type = "int"

[[outputs.prometheus_client]]
  listen = ":9273"

Prometheus can then scrape http://<telegraf-host>:9273/metrics.

Prometheus via MQTT Exporter

If you are already publishing via MQTT, the mqtt2prometheus exporter converts MQTT topics into Prometheus metrics:

# mqtt2prometheus.yaml
mqtt:
  server: tcp://mqtt-broker:1883
  topic_path: ESPGeiger-+/stat/+
  device_id_regex: "ESPGeiger-(?P<deviceid>[0-9a-f]+)/stat/.+"
  qos: 0
metrics:
  - prom_name: espgeiger_cpm
    mqtt_name: CPM
    help: Current counts per minute
    type: gauge
  - prom_name: espgeiger_usv
    mqtt_name: uSv
    help: Current microsieverts per hour
    type: gauge
  - prom_name: espgeiger_cpm5
    mqtt_name: CPM5
    help: 5-minute smoothed CPM
    type: gauge

InfluxDB via Telegraf

To write directly to InfluxDB instead of Prometheus:

[[inputs.http]]
  urls = ["http://192.168.1.100/json"]
  data_format = "json_v2"
  name_override = "espgeiger"
  # ... field config as above ...

[[outputs.influxdb_v2]]
  urls = ["http://influxdb:8086"]
  token = "YOUR_TOKEN"
  organization = "your-org"
  bucket = "radiation"

Node-RED

Node-RED can poll the JSON endpoint and route data anywhere:

[
  {
    "id": "poll",
    "type": "inject",
    "repeat": "60",
    "topic": "",
    "payload": "",
    "payloadType": "date"
  },
  {
    "id": "http",
    "type": "http request",
    "method": "GET",
    "url": "http://192.168.1.100/json",
    "ret": "obj"
  }
]

Wire poll → http → your destination (MQTT, database, dashboard, webhook, etc.).

Home Assistant

If using MQTT with Home Assistant autodiscovery enabled, ESPGeiger sensors appear automatically. See Home Assistant for details.

For REST polling without MQTT:

# configuration.yaml
rest:
  - resource: http://192.168.1.100/json
    scan_interval: 30
    sensor:
      - name: "Radiation CPM"
        value_template: ""
        unit_of_measurement: "CPM"
      - name: "Radiation uSv/h"
        value_template: ""
        unit_of_measurement: "μSv/h"
        device_class: "radiation"
      - name: "ESPGeiger WiFi RSSI"
        value_template: ""
        unit_of_measurement: "dBm"
        device_class: "signal_strength"
      - name: "ESPGeiger Free Heap"
        value_template: ""
        unit_of_measurement: "B"

Grafana Dashboard

Once data is in Prometheus or InfluxDB, Grafana can visualise it. A simple dashboard query for Prometheus:

# Current CPM
espgeiger_cpm

# 5 minute average
avg_over_time(espgeiger_cpm[5m])

# Alert when above threshold
espgeiger_cpm > 100