8× analog inputs 12-bit SAR ADC 50 kSPS I²C / Qwiic 0–5V · 0–20mA · 4–20mA Node-RED · MQTT · HA Tasmota
The IoTextra Analog3 provides eight independent differential analog input channels based on the Texas Instruments ADS7828 12-bit SAR ADC. Eight instrumentation-grade differential amplifier stages provide noise rejection before the signal reaches the ADC. Input protection diodes guard against over-voltage and ESD. Each channel is individually configurable for voltage or current measurement via solder bridge.
Key Specifications
- Supply voltage: 5 VDC (reverse polarity protected)
- ADC: ADS7828, 12-bit SAR, internal 2.5V reference
- Analog channels: 8 differential inputs (IN0–IN7)
- Sampling rate: up to 50 kSPS
- Voltage input: 0–5V (SB open)
- Current input: 0–20mA, 4–20mA (249Ω on-board shunt, SB closed)
- I²C address: configurable 0x48–0x4B via DIP switch (SW1), up to 4 modules per bus
- I²C modes: Standard (100kHz), Fast (400kHz), High-Speed (3.4MHz)
- Connectors: HOST-P12, Qwiic × 2, H1–H4 terminal blocks (3.5mm pitch)
- Indicators: analog power LED (LD1)
- Protection: Reverse polarity, TVS (SMAJ13CA), BAV99W clamp arrays, ESD on Qwiic
- Board size: 47 × 56 mm
Operation Modes
⎯ Standalone
Read analog data via HOST-P12 cable or Qwiic I²C connectors from any host controller.
⎙ Smart
Insert an IoTsmart module (ESP32-S3, RP2350, RP2040, XIAO) vertically into HOST-P12.
▭ Mezzanine
Install into an IoTbase carrier board (PICO, Nano) for expanded system integration.
Applications
🏭
Industrial Process Monitoring
Connect 4–20mA transmitters from pressure, temperature, and flow sensors directly into all 8 channels. 50kSPS rate captures fast transients alongside slow process variables on the same I²C bus. Use with Node-RED or IoTflow for threshold-based alarming.
⚡
IIoT & Predictive Maintenance
Current clamps on motor phases and voltage dividers on power rails — all 8 channels polled at high speed to detect vibration signatures and power anomalies before failure occurs. Works with Home Assistant or MQTT broker.
🌿
Smart Farming
Soil moisture, pH, and EC sensors on voltage channels; irrigation valve actuator feedback (4–20mA) on current channels — all delivered over a single I²C bus. Use Node-RED and IoTflow for time-based and sensor-triggered irrigation rules.
🏢
Building Automation (HVAC)
Temperature, humidity, CO₂, and light sensors with 0–5V or 4–20mA outputs across all 8 channels. Up to 4 modules on one I²C bus (0x48–0x4B) for zone-by-zone monitoring. Integrates with Home Assistant.
Compatible Microcontrollers
ESP32-S3 RP2350 RP2040 XIAO Raspberry Pi Any 3.3V / 5V I²C host
Software Ecosystem
IoTflow Node-RED Tasmota MQTT Blynk Home Assistant
