Home Automation 8-Layer Stackable HAT for Raspberry Pi

SequentSKU: MMP-1254
Sale price £68.40
incl. VAT
excl. VAT
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Compatible with:

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The ideal solution for your Raspberry Pi home automation projects - expandable and stackable up to 8 layers with other cards from the Sequent range!

Read temperatures in up to 8 zones with analog inputs. Control your heating and cooling system with the 8 onboard relays. Stackable design - add an additional 8-Relays board to control your sprinklers or a 4-Relays board to control high voltage appliances. Use the 8 optically isolated digital inputs for your security system. Activate the hardware watchdog to monitor and power cycle the Raspberry Pi in case of software lockup. Control four-light systems with the four PWM open-drain outputs (you supply external power up to 24V). Control four-light dimmers using 0-10V outputs.

Everything you need for Raspberry Pi home automation in a single, high-quality HAT.

For any technical questions about this product please email support@sequentmicrosystems.com

Note: Relays may be blue or black depending on the current batch and availability of components.

New Version!

This latest version of the Home Automation HAT has been redesigned to use only pluggable connectors. Due to the large number of I/Os, the previous version used a 40 pin, right-angle header. By removing the N-C contacts of the relays (seldom used), Sequent made enough room on the periphery for pluggable connectors with just a minor increase in board dimensions.

Despite the crowded layout, they also added a DC-DC, 5V to 12V step-up power supply to power the 0-10V outputs. Now you can control four dimmers without the need for an external 12V power supply!

Sequent also added a general-purpose push-button wired directly to a Raspberry Pi GPIO pin. You can write a script that captures the pin state and use it to turn on a relay or an output, or to shut down the Pi when a keyboard and monitor is not available.

Key Features

  • Eight relays with status LEDs and pluggable connectors
  • Eight layer stackable
  • Eight 12-bit A/D inputs
  • Four 13-bit DAC outputs (0-10V dimmers)
  • Four PWM 24V/4A open-drain outputs
  • Eight optically isolated digital inputs
  • Contact closure/Event counters up to 100 Hz
  • Four Quadrature Encoder inputs
  • 30 GPIOs (26 GPIOs from Raspberry Pi + 4 new)
  • Pluggable Connectors 26-16 AWG for all ports
  • On-board hardware watchdog
  • On-board resettable fuse
  • Reverse power supply protection
  • Brass standoffs, screws and nuts included
  • Hardware self-test (with optional loop-back cable)
  • Open-source hardware, schematics available
  • 32-bit processor running at 48MHz
  • Command line 
  • Python Library
  • Node-RED Nodes
  • Domoticz Plugin
  • OpenPLC example integration
  • Firmware Update


The card is compatible with all Raspberry Pi versions from Zero to 4. It shares the I2C bus using only two of the Raspberry Pi’s GPIO pins to manage all eight cards. This feature leaves the remaining 24 GPIOs available for the user.

Power Requirements

The Home Automation card needs 5V to operate and can be powered from Raspberry Pi or from its own 2.1mm barrel connector. The tip is +5V and the ring is ground. The onboard relay coils are also powered from the 5V. A local 3.3V regulator powers the rest of the circuitry. The card needs 50mA to operate with all relays off. Each relay needs up to 80 mA to turn on.


The 8 onboard relays have contacts brought out to heavy-duty pluggable connectors, which make the card easy to use when multiple cards are stacked up. Relays are grouped in two sections of four relays each, with one common terminal and one N-O contact for each relay.

Relays are rated 10A/24VDC and 250VAC, but due to the board geometry limitation, relays 6 and 7 can switch 3A and 24V, while all the others can switch 6A and 24V AC or DC. You can switch larger loads of up to 8A and 240VAC by stacking separate 4-Relays cards, which also adds four extra inputs.

Status LEDs show when RELAYS are ON or OFF.

Stacking Multiple Cards

Up to eight Home Automation cards can be stacked on your Raspberry Pi. Each card is identified by jumpers you install to indicate the level in the stack. Cards can be installed in any order. The three position jumper on the upper right corner of the card selects the stack level.

Home Automation card Stack Levels

Card Layout

Home Automation Card layout

I/O Pinout

The Home Automation is accompanied by a Credit Card size, plastic laminated card which shows the I/O pinouts. Keep it handy. The back of the card shows the Raspberry Pi GPIO Connector pinout.

Home automation card pinout

Package Contents

  • 1x Home Automation Card
  • Mounting Hardware set:
    • 4x M2.5x18mm male-female brass standoffs
    • 4x M2.5x5mm brass screws
    • 4x M2.5 brass nuts
  • 2x Stack level jumpers/shunts
  • 1x Connector plug set (for all card connectors)
  • 1x Laminated plastic IO pinout reference card

Optional Accessories

DIN-RAIL Mounting

The Home Automation card can be installed parallel on a DIN-Rail using the DIN-Rail Kit Type 1, or perpendicular using the DIN-Rail Kit Type 2.

Breakout Boards

Break-out boards provide a convenient and robust way of accessing the IO pins. For screw-mount wiring, you can use the Break-Out Kit Type 1. The Break-Out Kit Type 2 provides wiring with pluggable connectors.

Self-Test Cable

This self-test cable allows you to test groups of three inputs and outputs on the HAT.

Electrical Specification

  • Power supply: Pluggable Connector, 5V/3A
  • Power consumption: 50mA (all relays off), 700mA (all relays on)
  • On board resettable fuse: 3A
  • Open Drain outputs: maximum 3A, 24V
  • Relays 1,2,3,4,5,8: N-O contacts,  6A/24VAC or DC
  • Relays 6,7: 3A/24VAC or DC
  • Analog Inputs:
    • Maximum input voltage: 3V
    • Input Impedance: 50 KΩ
    • Resolution: 12 bits  
    • Sample rate: 250 samples/sec.
  • DAC Outputs:
    • Resistive load: Minimum 1 KΩ
    • Accuracy: ±1%
  • Opto-isolated Digital Inputs:
    • Input Forward Current: Typical 5 mA, maximum 50 mA
    • Input Series Resistor: 1K
    • Input Reverse Voltage: 5V
    • Input Forward Voltage: 25V @ 10 mA
    • Isolation Resistance: Minimum 1012 Ω

Mechanical Specification

Home Automation Card Mechanical Specification


Software Interfaces

You can write your own application using the Command Line or Python Libraries provided. No programming is required if you use the Node-Red nodes we supply. You can drag and drop the functional blocks to design your application. Examples are provided at GitHub.


Groups of three inputs and outputs can be self-tested with the help of a loopback cable. The cable can be purchased or made yourself using three of the connectors provided with the kit. See the software section here for more information.

Field Calibration

The analog inputs and outputs are calibrated from the factory with 1% precision. Field calibration up to 0.1% can be obtained using a precision voltage meter.  Calibration instructions coming soon.

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's servers. More instructions about the process can be found on GitHub. Please make sure there is no process, like Node-Red or python scripts, that tries to access the card during the update process.


The Home Automation card contains a built-in hardware watchdog that will guarantee that your mission-critical project will recover and continue running even if Raspberry Pi software hangs up. After power-up, the watchdog is disabled and becomes active after it receives the first reset.

The default timeout is 120 seconds. Once activated, if it does not receive a subsequent reset from Raspberry Pi within 2 minutes, the watchdog cuts the power and restores it after 10 seconds.

Raspberry Pi needs to issue a reset command on the I2C port before the timer on the watchdog expires. The timer period after power up and the active timer period can be set from the command line. The number of resets is stored in flash and can be accessed or cleared from the command line. All the watchdog commands are described by the online help function.


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/ioplus-rpi.git
cd /home/pi/ioplus-rpi
/ioplus-rpi$ sudo make install
/ioplus-rpi$ ioplus

The program will respond with a list of available commands.

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