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Pi HAT with 16 opto-isolated inputs can stack for up to 128

Feb 19, 2021 — by Eric Brown 4,506 views

Sequent’s $40 “16-Inputs for Raspberry Pi” HAT provides 16 opto-isolated, 3-240V AC/DC digital inputs and an RS-485 port and can be stacked 8x high for up to 128 inputs.

Sequent Microsystems has included optically isolated digital inputs on its earlier Raspberry Pi Mega-IO Expansion Card (8x opto-inputs) and MegaIO-IND (4x) Raspberry Pi HATs. Now, it has returned to Kickstarter to successfully launch a HAT with 16x opto-isolated, 3-240V AC/DC inputs for data acquisition.

16-Inputs for Raspberry Pi HAT with Pi (left) and rear view
(click images to enlarge)

The 16-Inputs for Raspberry Pi HAT can be purchased individually for $40 — or $45 if you want it in March instead of April. The stackable HATs are also available in bundles available in May including 32x opto-isolated digital inputs ($70), 64x ($130), and 128x ($240). The latter gives you a $2 per channel value.

The HAT expands upon the up to 26x inputs offered by the Raspberry Pi, which lack optical isolation against electrical interference. Because the device communicates with the Pi via I2C, all 26 default inputs are still available.


The 16-Inputs for Raspberry Pi HAT supports both AC and DC signals, and the input ranges can be jumper-selected for each channel, from 3 volts to 24 volts or from 24 volts to 240 volts. The inputs also offer reverse polarity protection.

16-Inputs for Raspberry Pi HAT in four-pack configuration on DIN-rail (left) and detail view
(click images to enlarge)

Other features on the card include an RS-485 port, a power LED, and a pushbutton that can be used to shut down the Pi. A DIN-rail mounting kit is available for multiple card bundles.

The HAT is powered at 5V from the Pi or from a 2-pin pluggable connector. There is also a 3A fuse for configurations in which the Pi is being powered from the HAT.

Command line and Python drivers plus source code can be downloaded from GitHub, and a native Node-Red node can be used to display the inputs in the browser. Schematics are included.

Further information

The 16-Inputs for Raspberry Pi HAT is available now starting at $40, with shipments starting in March, April, or May, depending on the package. Pricing discounts range from 11 percent to 33 percent off MSRP. More information may be found on Sequent’s Kickstarter page.

(advertise here)

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2 responses to “Pi HAT with 16 opto-isolated inputs can stack for up to 128”

  1. Basti says:

    I’m a little sceptical about it, I’ll follow it and wait for some reviews of it but 128 Optocouplers might be notable in terms of power consumption at 240V. I’m also curious if there will be some insulating tape for the relative close looking usb and ethernet Ports. I’m still hoping someone releases something more efficient than a it led with some resistors on 240v. Maybe something in the direction of those battery powered pens which light an Led when close to mains voltages?

  2. Marc G. says:

    Granted, this story is 3 years old, but they are *not* 3-240V inputs. They are 3-24V inputs (AC or DC). Here is a link:

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