Sfera Labs Launches Sensor Module Based on Raspberry Pi 4

Article By : Maurizio Di Paolo Emilio

Sfera Labs has launched a multi-function module based on Raspberry Pi Compute with several sensors and connectivity options for residential and commercial installations.

Sfera Labs has launched a multi-function module based on Raspberry Pi Compute with several environmental sensors and connectivity options to help engineers develop products for residential and commercial installations. The Exo Sense Pi board integrates temperature and humidity sensors, air quality, light and PIR-based motion detection sensors, as well as a microphone for ambient noise measurements and audio recording.

In an interview with EE Times Europe, Giampiero Baggiani, founder, Maria Chizzali, COO, and Ulderico Arcidiaco, CEO & founder, at Sfera Labs, illustrate the potential of the Exo Sense Pi board for the industrial market. Typical applications include environmental monitoring and data gathering, BLE positioning, indoor people and assets tracking, rooms management and access control as well as voice control.

“Following our Exo Sense Py, which is on the Pycom platform, the new Exo Sense Pi has a Raspberry Pi 4 computing core. The new form factor of Raspberry Pi module, compared to previous versions, makes it more convenient to embed into our sensor module and allows us to reap the benefits of its processing power and RAM management capabilities,” said Baggiani.

Baggiani outlined the growing demand for environmental quality monitoring solutions, even more so with Covid-19. Everyone is more concerned about the quality of the environment inside offices, homes, buildings, and hospitals. Access control is used to count people inside a room and it is imperative to maintain an adequate level of quality.

Why a new board?

Sfera Labs mentioned three key factors in choosing a new sensor board. One of these factors is the ability to offer a solution that is not based on a microcontroller but on a processor such as the Raspberry Pi.

“This opens up a spectrum of applications compared to a traditional microcontroller because here you have the raw power to perform almost any analysis task,” explained Arcidiaco. The other two factors are the ability to run a full access control solution and open-source libraries to simplify coding. The board can also be customized to suit professional needs, Chizzali added.

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Figure 1: Exo Sense Pi
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Figure 2: PIR Sensor implemented on the board

Features

Exo Sense Pi is compatible with all Raspberry Pi Compute Module 4 boards. A microSD slot is present on Exo Sense Pi to use external flash memory cards with the CM4 Lite. The Raspberry Pi Compute Module 4 incorporates a high-performance quad-core ARM Cortex-A72 processor, Wi-Fi, Bluetooth 5.0 and Bluetooth Low Energy (BLE) wireless interfaces, up to 8GB RAM and 32GB eMMC Flash memory. The sensors onboard are Sensirion SHT40 temperature and humidity sensor, Sensirion SGP40 air quality (Volatile Organic Compounds) sensor, Texas Instruments OPT3001 digital ambient light sensor (ALS) with high-precision human-eye response, Panasonic EKMC PIR motion sensor. Other components include TDK ICS-43432 digital I²S microphone for audio recording and environment noise detection, two digital inputs for potential-free contacts or TTL level input/output with 1-Wire, I²C and Wiegand support, one open collector output with a maximum output current of 100mA, protected against over-current and short circuits, standard RS-485 interface to the Compute Module UART serial lines, with electrostatic discharge (ESD) protection, real time clock with replaceable CR1025 Lithium / Manganese Dioxide back-up battery and Microchip ATECC608 secure element chip.

Figure 3 shows the SHT40 and SGP40 sensors soldered onto a raised printed circuit board (PCB) close to the lower left ventilation grille. The slight temperature gradient between the inside of the case and the environment air temperature creates a natural airflow through the upper grille to improve the performance of the sensors.

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Figure 3: SHT40 and SGP40 sensors soldered onto a raised printed circuit board (PCB)

The heat generated by the Compute Module and the Exo Sense Pi components must be taken into account and properly compensated to ensure accurate readings from the SHT40 and SGP40 sensors. Arcidiaco explains that Sfera Labs achieved this by using two LM75A temperature sensors – one placed on the raised PCB close to the sensors, and the other underneath the Compute Module – which are connected to the I²C bus.

Texas Instruments’ OPT3001 digital ambient light I²C sensor implements accurate optical filtering to match how the human eye responds to light and rejects 99% of IR. The light intensity range is from 0.01 lux to 83 k lux.

Exo Sense Pi is compliant with the CE electromagnetic compatibility standard for emissions in residential environments and immunity in industrial environments. It is also compliant with the FCC and IC electromagnetic compatibility standards.

This article was originally published on EE Times Europe.

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