SendIt - ADC Input Multitool

SendIt Rev C

SendIt is an open-hardware, open-firmware controller designed as a multi use tool for handling various inputs with a focus on DIY marine usage. It runs on the Yarrboard Framework and provides a clean web UI for configuration, and multiple different APIs for accessing your data.

Built on the ESP32-S3, SendIt has 8 channels of 16-bit ADC with 5 different types of configurable input circuits. With this board, each channel can be individually configured to handle these types of inputs:

  • 4-20ma Transducers/Senders: sender between +VE and GND
  • Positive Switching: 0-32v, voltage divider acts as pulldown when NC, switch between SIGNAL and +VE
  • Negative Switching: 1k ohm, top half of voltage divider acts as pullup, switch between SIGNAL and GND
  • 0-32v: simple voltage divider, voltage wired to SIGNAL
  • 0-10k ohm: voltage divider, external resistor wired from SIGNAL to GND
  • 0-5v: simple voltage divider, voltage wired to SIGNAL
  • Thermistor: 0-10k ohm, wired as normal
  • Raw/Passthrough: no extra circuitry - wire your own custom circuit

User Interface

SendIt UI

  • Local HTML5 web interface served directly from the ESP32
  • Fast, mobile-friendly design
  • Works on phones, laptops, and supported MFDs
  • Real-time dashboard with sensor readings
  • Full configuration editor UI - no editing config files

Integrations

  • MQTT publishing
  • SignalK
  • Home Assistant
  • HTTP/REST endpoints
  • WebSocket real-time control

Example User Interface