# Analog sensor -\> ESP Home -\> MQTT -\> Node Red

**URL:** <https://discourse.nodered.org/t/analog-sensor-esp-home-mqtt-node-red/100374>\
**Category:** Hardware\
**Created:** [13 February 2026 17:02 UTC](https://discourse.nodered.org/t/analog-sensor-esp-home-mqtt-node-red/100374 "2026-02-13T17:02:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Elindo586](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/elindo586/32/105439_2.png) [@Elindo586](https://discourse.nodered.org/u/Elindo586)\
**Post date:** [13 February 2026 17:02 UTC](https://discourse.nodered.org/t/analog-sensor-esp-home-mqtt-node-red/100374/1 "2026-02-13T17:02:01Z")

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Hello!!!

Would anybody have any experience / recommendation for an I/O device that can handle analog sensors?

The setup I would like.. so far I think.. would be kind of like this:  
Analog sensor -\> I/O device to configured ESP Home -\> MQTT -\> MQTT Broker -\> Node Red

^^^ I will not be using Home Assistant... I will just talk directly to Node Red.

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**Author:** ![TotallyInformation](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/totallyinformation/32/31_2.png) [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)\
**Post date:** [13 February 2026 17:25 UTC](https://discourse.nodered.org/t/analog-sensor-esp-home-mqtt-node-red/100374/2 "2026-02-13T17:25:28Z")

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Most of (maybe all?) the microprocessors supported by ESPHome support analogue inputs:

- **ESP8266** : Only **GPIO17 (A0)** can be used for ADC input. You can also measure **VCC** voltage directly by setting `pin: VCC` , useful for low-voltage detection in battery-powered setups.
- **ESP32** : Multiple pins support ADC (e.g., GPIO32–GPIO39 for ADC1, GPIO0, GPIO2, GPIO4, etc. for ADC2). Use `attenuation` to measure voltages above 1.1V (e.g., `12dB` for up to ~3.9V).
- **RP2040 (Raspberry Pi Pico)** : GPIO26–GPIO29 are available. You can also measure **VSYS** via `pin: VCC` (GPIO29), though it may interfere with WiFi on Pico W.
- **nRF52840** : Supports AIN0–AIN7, VDD, and VDDHDIV5.

(The above from AI so double-check).

What kind of sensor do you want to use?

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**Author:** ![edje11](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/edje11/32/572_2.png) [@edje11](https://discourse.nodered.org/u/edje11)\
**Post date:** [13 February 2026 21:31 UTC](https://discourse.nodered.org/t/analog-sensor-esp-home-mqtt-node-red/100374/3 "2026-02-13T21:31:08Z")

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> [@TotallyInformation](#):
>
> GPIO0, GPIO2, GPIO4, etc. for ADC2

Note: On an **ESP32** , you **cannot (reliably) use ADC2 when WiFi is enabled**.

### 🔧 Explanation

The ESP32 has two ADC units:

- **ADC1** → works normally, even when WiFi is active
- **ADC2** → is used internally by the WiFi driver

As soon as you enable WiFi (`WiFi.begin()`), the WiFi subsystem takes control of **ADC2** , which means:

- `analogRead()` on ADC2 pins will not work
- you may get a value of 0
- or you may receive error messages

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**Author:** ![dynamicdave](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dynamicdave/32/96_2.png) [@dynamicdave](https://discourse.nodered.org/u/dynamicdave)\
**Post date:** [13 February 2026 22:28 UTC](https://discourse.nodered.org/t/analog-sensor-esp-home-mqtt-node-red/100374/4 "2026-02-13T22:28:45Z")

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You could also "bolt" an ADS1115 (16-bit, 4 channel ADC) on to the ESP32 using the I2C bus.  
My "go to" microcontroller (at the moment) is the ESP32-S2-Mini or ESP32-C3-Super-Mini.

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [14 April 2026 22:28 UTC](https://discourse.nodered.org/t/analog-sensor-esp-home-mqtt-node-red/100374/5 "2026-04-14T22:28:54Z")

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