Configuration¶

All settings are managed through the SoftAP Web Portal — a self-hosted HTTP interface served directly by the ESP32-C3 over its own Wi-Fi access point. No mobile app, no cloud account, and no re-flashing is required to change any parameter.

Entering the Portal¶

On first boot (or after a full erase flash), the node automatically detects that it is unconfigured and launches the portal.

At any time during normal operation:

Hold the BOOT button (GPIO9) for 3 seconds.
The firmware halts the current operational cycle and starts the SoftAP.
From any device with Wi-Fi:

Setting	Value
SSID	`EnvNode-Setup`
Password	`configure`
Portal URL	`http://192.168.4.1`

Portal exit

After submitting the form, the portal saves all values to NVS flash and performs a hard reboot. The device immediately re-enters normal operational mode with the new configuration.

Wi-Fi Settings¶

Field	Description	Required
SSID	Name of your 2.4 GHz Wi-Fi network	Yes
Password	Wi-Fi password (WPA2)	Yes (if secured)

The node operates in STA (client) mode during normal cycles. The SoftAP is only active while the portal is open.

Notification Settings¶

All three channels are fully optional and independent. A failure (or missing credentials) on any channel never blocks the others.

Telegram¶

Delivered via the Telegram Bot API.

Field	Description
Bot Token	Obtained from @BotFather (`123456:ABC-abc…`)
Chat ID	Your personal or group chat numeric ID

Leave both fields blank to disable Telegram alerts entirely.

Discord¶

Sent as { "content": "<message>" } via a Discord Webhook.

Field	Description
Discord Webhook URL	Full webhook URL from your Discord channel settings

Returns HTTP 204 on success.

Custom Webhook¶

A POST request with a structured JSON body is sent to any URL you specify:

{
  "event": "alert",
  "message": "Low soil moisture alert!...",
  "soil_mv": 2450,
  "temp": 22.5,
  "humidity": 61.0
}

Field	Description
Custom Webhook URL	Any HTTPS endpoint that accepts a POST with `Content-Type: application/json`

MQTT Settings¶

Connects to any standard MQTT broker (Mosquitto, EMQX, HiveMQ, etc.) and publishes both Home Assistant Auto-Discovery configs and sensor state values on every wake-up cycle.

Field	Description	Default
Broker Host / IP	Bare IP (`192.168.1.10`) or full URI (`mqtt://host:1883`)	`""` (disabled)
Port	TCP port	`1883`
Topic Prefix	Base path for all state topics	`d7main/sensor`
Username	Optional MQTT credentials	`""`
Password	Optional MQTT credentials	`""`

Home Assistant Auto-Discovery

On each boot the node publishes one discovery config payload per entity to homeassistant/sensor/<device_id>_<entity>/config with retain=1. Home Assistant picks these up automatically — no manual entity configuration needed.

Leave Broker Host / IP blank to disable MQTT entirely. The rest of the wake-up cycle (sensors, alerts) is unaffected.

Alert Threshold¶

Field	Description	Default
Soil Alert Threshold (%)	Alerts fire when calculated moisture % falls below this value	`30%`

If ADC calibration has not been set, moisture percentage cannot be calculated and threshold-based alerts are skipped. Raw mV values are still logged and published over MQTT.

ADC Calibration¶

The capacitive soil moisture sensor outputs an analog voltage that varies by sensor batch, cable length, and soil composition. Two reference readings must be taken to map mV → %.

Field	Description	How to measure
Dry reference (mV)	ADC reading with sensor fully in dry air	Read from the portal's live mV display with sensor out of soil
Wet reference (mV)	ADC reading with sensor fully submerged	Submerge sensor in a glass of water, read live mV

The portal shows a live mV reading that updates every 2 seconds while the portal is open, making calibration straightforward.

Polarity

Capacitive sensors produce lower voltage when wetter. Ensure Dry mV > Wet mV. If the values are swapped the moisture % will calculate as 0% for all readings.

Mapping formula:

moisture_pct = (v_dry - current_mv) * 100 / (v_dry - v_wet)

Clamped to [0, 100]. Matches the JavaScript calcPct() function in the portal.

Serial Monitor Output¶

Connect at 115200 baud to observe the full operational log:

I APP_MAIN: ========================================
I APP_MAIN:  ESP32_EnvironmentalNode booting on ESP32-C3
I APP_MAIN: ========================================
I APP_MAIN: [HEAP] Boot baseline — Free: 263144 B
I APP_MAIN: Device is configured. Starting normal operation.
I APP_MAIN:   SSID       : MyNetwork
I APP_MAIN:   MQTT Broker: 192.168.1.10
I APP_MAIN:   Threshold  : 30%
I APP_MAIN: Reading sensors...
I APP_MAIN: Sensors: soil=2310 mV (47%) | BMP280: 22.3 C / 1012.4 hPa | DHT22: 22.1 C / 61.5%
I APP_MAIN: [HEAP] After sensor reads — Free: 262804 B
I SYS_MQTT: [MQTT] Connected to broker.
I SYS_MQTT: [MQTT] Discovery published: 6 entities.
I SYS_MQTT: [MQTT] State published: 7 topics.
I APP_MAIN: [HEAP] After MQTT cycle — Free: 263084 B
I APP_MAIN: Soil moisture OK (47% >= threshold 30%). No alert sent.
I APP_MAIN: [HEAP] Pre-sleep — Free: 263084 B | Min-ever: 218432 B
I APP_MAIN: Entering deep sleep for 1800 seconds.