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SKU: SM-I-018

Sixteen Analog-Digital Inputs 8-Layer Stackable HAT for Raspberry Pi

Name: Sixteen Analog-Digital Inputs 8-Layer Stackable HAT for Raspberry Pi
Brand: Sequent Microsystems
SKU: SM-I-018
Price: 95.0 USD
Availability: InStock

Sixteen Inputs: 1K/10K Thermistors, 0-10V, Dry Contact, Event Counters; RS485/MODBUS; RTC; Hardware Watchdog.

In stock

$95.00

Product variants

Overview

Eight-layer stackable universal input HAT for Raspberry Pi with 16 truly universal inputs, each software-configurable as a 1K/10K thermistor, 0-10V or 4-20mA analog input, dry contact, or counter — all without jumpers. Includes a Real-Time Clock with battery backup, hardware watchdog, TVS protection on all inputs, and RS485/MODBUS for standalone PLC integration.

16 universal inputs — each software-configurable as thermistor, 0-10V, 4-20mA, dry contact, or counter
All input mode selection in software — no jumpers or hardware changes required
TVS protection on all inputs; hardware watchdog; Real-Time Clock with battery backup
RS485/MODBUS for standalone or PLC integration
Up to 8 cards stack for 128 inputs on one Raspberry Pi
Compatible with all Raspberry Pi versions from Zero to 5

Works with Open Automation Software

Compatible with widely used tools for control, monitoring, and system integration.

INTERFACES AND I/O

I/O's	Communication	Software Integration
• 16 Universal Inputs (software-selectable per channel)	• I2C Port to Raspberry Pi	• Command Line
• — 1K / 10K Thermistors	• RS485/MODBUS Port	• Python Library
• — 0-3.3V / 0-10V / 4-20mA Analog Inputs		• CODESYS Library
• — Dry Contact / Counter Inputs (500Hz max)		• Home Assistant
• 16 Bi-Color Status LEDs		• Arduino Library
• Real-Time Clock with CR2032 Battery Backup
Other Features
• All input modes selected in software — no jumpers required
• TVS protection on all inputs \| Hardware watchdog \| Resettable fuse 3A
• 5VDC/4A external supply; provides 5V/3A to Raspberry Pi
• Eight-layer stackable (128 inputs) \| Uses only I2C — 24 GPIO pins remain free

DESCRIPTION

The Sixteen Analog-Digital Inputs HAT brings truly universal inputs to the Raspberry Pi. Each of the 16 channels can be individually configured in software to read 1K or 10K thermistors, 0-10V or 4-20mA analog signals, or digital contact closure and counter inputs — all without any hardware changes.

Universal Inputs

Each channel is individually configurable to read 1K or 10K thermistors, 0-3.3V or 0-10V or 4-20mA analog signals, or digital dry contact and counter inputs with a maximum frequency of 500Hz.

Software Input Selection

All input mode selection is performed in software via the command-line interface. No jumpers, no DIP switches for input configuration — reconfigure any channel at any time without touching the hardware.

Real-Time Clock

The Real-Time Clock with CR2032 battery backup keeps accurate time almost indefinitely through power failures, making the card ideal for data logging and time-stamped event recording.

RS485/MODBUS

Connect the card to industrial automation systems using the RS485/MODBUS port. The RS485 can be driven either from the local processor (implementing MODBUS RTU device) or directly from the Raspberry Pi using dedicated GPIO pins.

Hardware Watchdog

The built-in hardware watchdog guarantees recovery if Raspberry Pi software hangs. Disabled at power-up, activates after the first reset command. Default 120s timeout; cuts power and restores after 10 seconds.

Protection

TVS diodes on all inputs protect against ESD and transient spikes. An onboard resettable fuse (3A) protects against accidental shorts. A 32-bit processor running at 64MHz handles all local processing.

Stacking

Up to 8 cards stack on one Raspberry Pi for 128 universal inputs. Three DIP switch positions (ID0, ID1, ID2) select the stack level. Uses only I2C — 24 GPIO pins remain free.

TECHNICAL DETAILS

CARD LAYOUT

Sixteen Analog-Digital Inputs HAT for Raspberry Pi — card layout

MECHANICAL SPECIFICATIONS

Sixteen Analog-Digital Inputs HAT Mechanical Specifications

DIP SWITCH AND STACKING

The onboard DIP switch configures both the stack address and the RS485 port behavior. Up to eight Sixteen Analog-Digital Inputs HATs can be stacked on one Raspberry Pi; cards can be stacked in any order. Note: input mode selection (thermistor, voltage, current, digital) is done entirely in software — no DIP switch positions are used for input configuration.

Switch	Name	Function
ID0	Stack ID bit 0	Binary stack address bit 0 (LSB) — sets card level 0–7
ID1	Stack ID bit 1	Binary stack address bit 1
ID2	Stack ID bit 2	Binary stack address bit 2 (MSB)
RX	RS485 RX select	ON: Raspberry Pi receives RS485 directly
TX	RS485 TX select	ON: Raspberry Pi drives RS485 directly

ELECTRICAL SPECIFICATIONS

Power
Power supply	3.5mm Pluggable Connector, 5V / 4A
Power consumption	50 mA
Onboard resettable fuse	3 A
Power provided to Raspberry Pi	5V / 3A

0–10 V Inputs
Maximum input voltage	12 V
Input impedance	20 KΩ
Resolution	12 bits
Full scale linearity	0.15%

Digital / Counter Inputs
Max. counter frequency	500 Hz

POWER REQUIREMENTS

Power supply: The card requires an external 5VDC/4A power supply connected to its own pluggable connector. The card supplies 5V and up to 3A to the Raspberry Pi on the GPIO bus, eliminating the need for a separate Raspberry Pi power supply. A local 3.3V regulator powers the rest of the circuitry. The card needs only 50mA to operate.

PLUGGABLE CONNECTORS

All I/Os are connected to heavy-duty (8A rated) 3.5mm pitch pluggable connectors which make field wiring convenient for installation and debugging. Connectors can be unplugged from the board without disturbing the rest of the installation. Wire gauge: 26–16 AWG.

FIELD CALIBRATION

All analog inputs are calibrated at the factory, but firmware commands allow the user to re-calibrate the board or calibrate it to higher precision. Calibration is performed in two points; select points as close as possible to the two ends of the measurement scale.

To calibrate the inputs, the user must provide known analog reference signals. For example, to calibrate 0-10V inputs, the user must provide an accurate adjustable 0-10V power supply. Calibration is performed using the command-line interface provided.

COMMUNICATION INTERFACES

RS485 / MODBUS

The Sixteen Analog-Digital Inputs HAT includes a standard RS-485 transceiver that can be accessed by the local processor or by the Raspberry Pi. The operating mode is configured using the TX and RX DIP switches.

When TX and RX are set to ON, the Raspberry Pi communicates directly with any device that has an RS-485 interface. In this mode the card functions as a passive bridge. To use this configuration, the onboard processor must first release control of the RS-485 bus:

~$ 16univin [0] cfg485wr 0 0 0 0 0

When TX and RX are set to OFF, the card operates as a MODBUS RTU slave. Any MODBUS master can access all inputs using standard MODBUS commands. A full list of supported MODBUS registers is available on GitHub.

In-and-out connectors on the RS485 port simplify daisy-chain wiring to other devices.

HARDWARE WATCHDOG

The Sixteen Analog-Digital Inputs HAT contains a built-in hardware watchdog which guarantees that your mission-critical project will recover and continue running even if Raspberry Pi software hangs. After power-up the watchdog is disabled, and becomes active after it receives the first reset or first period set.

Watchdog Parameters
Default timeout	120 seconds
Power-off duration on trigger	10 seconds
Initial timeout period	Configurable — allows time for Raspberry Pi to boot and start the application
Running timeout period	Configurable — normal operating timeout
Reset counter	Stored in non-volatile flash; can be read or cleared at any time

For a full list of watchdog commands, run: 16univin -h

COMPATIBILITY

Interface	I2C (address range 0x58 to 0x5F)
GPIO used	GPIO2 (SDA), GPIO3 (SCL) — 2 pins only; remaining 24 GPIO pins stay free
Max stack	8 cards of each type; different Sequent HATs can be freely mixed
Compatible with	All Raspberry Pi versions from Zero to 5 (40-pin GPIO header)

FIRMWARE UPDATE

The card firmware can be updated in the field by running a command. The update is made with the latest firmware version located on Sequent Microsystems' servers.

WARNING: Make sure there is no process — such as Node-RED flows or Python scripts — trying to access the card during the update process. Accessing the card during an update may corrupt the firmware.

Running the Update

~$ cd ~/16univin-rpi/update/

~/16univin-rpi/update$ ./update <id>

Replace <id> with the board stack address (0–7). Full instructions including recovery procedures are available at:

https://github.com/SequentMicrosystems/16univin-rpi/blob/main/update/README.md

DOWNLOADS

User's Guide (PDF)	Schematics (PDF)	CAD	Software & Integrations
User's Guide V1.0	Schematics V1.0	3D STEP Model	Command Line
		3D Printing Enclosure	Python Libraries
			Node-RED Data Acquisition Example
			CODESYS Library
			Home Assistant
			Arduino Library

WHAT'S INCLUDED

When you purchase the card you will receive the following items:

1. Sixteen Analog-Digital Inputs HAT for Raspberry Pi

2. Mounting Hardware
	Four M2.5×18mm male-female brass standoffs Four M2.5×5mm brass screws Four M2.5 brass nuts

3. Connector Plugs for all Inputs and Outputs
	All required mating connector plugs for field wiring

QUICK START

Plug your card on top of your Raspberry Pi and power up the system.
Enable I2C communication on Raspberry Pi using raspi-config.
Install the software from GitHub:

~$ git clone https://github.com/SequentMicrosystems/16univin-rpi.git

~$ cd 16univin-rpi

~/16univin-rpi$ sudo make install

~/16univin-rpi$ 16univin

The program will respond with a list of available commands. To read more about the CLI, please refer to the README file. If you would rather use a different platform, you can access the same functionality through dedicated, ready-to-use integrations in the Downloads tab above.

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Building BACnet controllers

I’ve been using several Sequent variations while developing custom BACnet devices in Python. These boards have been excellent for rapid development because they eliminate the need for custom circuit design or soldering, allowing me to focus on software and system architecture.

My current project uses a FastAPI server with a web-based configuration UI to build a BACnet-enabled controller that replaces my previous Nixie pool controller. Using the RS-485 interface, I communicate with Pentair variable-speed pumps. I developed a BACnet stack that supports all 16 possible pump addresses, allowing each pump to operate independently while Not having to remain network-bound when the pump is off. This means a technician can start a pump in quick-clean mode or adjust parameters without disconnecting the network or powering down the controller, all they have to do is turn off the pump or need it after hours.

The hardware all variations I have used have been very reliable and flexible for this type of automation work. It has allowed me to build a prototype controller quickly and focus on higher-level functionality like BACnet integration and UI development. I’m also building a Swift-based frontend as part of a larger home and building automation system. It’s going to be a while lol!

After a stroke in 2024, projects like this have helped keep my mind active and engaged (better than TV!). Having reliable, ready-to-use boards makes it possible to keep developing new ideas without needing to design custom electronics from scratch.

Overall, these boards are an excellent platform for prototyping automation controllers and are a strong alternative to older platforms like the commercial BASpi module that are fantastic I was using, that are now for training only.

Very versatile unit

That is a very interesting concept for unknown input capturing tasks with a minimum of components - great job!