Key Features

• Data collection sources include: MQTT, REST API, HTTP, TCP CSV, Serial/USB. Additionally, other data collection source are available via custom data collectors.
• The software allows one to filter, transform, aggregate, monitor, and act on sensor data.
• Data storage is local and maintained in a CSV database.
• Cache and send data to upstream services like MQTT and REST APIs.
• All data visualization is available via a web interface.
• Alerting can be done via email or SMS.
• Software is available to run on PC, Mac, Linux, Raspberry Pi, and BeagleBone.

Software Options

• JEDI One is geared towards Makers and early prototypes (single user, up to 10 devices)
• JEDI Pro is for commercial applications (up to 10 users, up to 200 devices)

Example of a dashboard from a TechForum post on MachineChat, there's 30+ in depth posts on how to get going with various platforms and sensors: MachineChat category on TechForum

Popular MachineChat Content

Inter-integrated circuit (I2C)

• Inter-Integrated Circuit (I2C) Protocol is a two-wire serial connection designed to allow multiple end points to communicate with one or more controllers. It is a half-duplex protocol, meaning data can only be sent in one direction from the controller to many end points at a time.
• Data transfer speeds for I2C can range from 0.1 to 5 Mbit/s, depending on the exact IC and bus configuration. However, due to the simple nature of the two-wire bus connection it can have significantly slower data rate compared to the more complex SPI connection.

Improved inter-integrated circuit (I3C)

• Improved Inter Integrated Circuit (I3C) Protocol is a two-wire serial connection designed to allow multiple end points to communicate with one or more controllers. It shares many things in common with I2C (including being half-duplex)
• One major improvement over the I2C standard is that the I3C standard defines a signaling protocol that allows for multiple chips on the same bus to control the bus communication, as well as being lower power and higher data rate
• Data transfer speeds for I3C bus can range from 400Kbit/s for legacy I2C data rates up to 33 Mbit/s in Ternary mode, but the Standard data rate (SDR) of 12.5 Mbit/s is common

Serial Peripheral Interface (SPI)

• Serial Peripheral Interface (SPI) Protocol is a 3 or more-wire bus connection to allow many different endpoints to communicate with one centralized controller IC.
• As a full-duplex, synchronous serial connection, SPI connections require a synchronized clock signal from the central controller that all participants on the SPI network share, this allows for a higher speed bidirectional data Transfer. Up to 60 Mbps can be achieved when both source and receiver IC are near each other for example, within the same circuit board.
• The drawback to SPI is that when adding more endpoints on the same bus requires more available I/O pins to act as chip select pins and more wired connections to be made to the controller IC, this can make expansion of existing network difficult.

Universal Asynchronous Receiver/Transmitter (UART)

• Universal asynchronous receiver-transmitter (UART) is a bidirectional asynchronous serial connection, usually implemented in hardware which can be setup for simplex, half-duplex, or full-duplex data transmission with data sent as individual bits one by one in sequence from least to most significant.
• Without a shared clock signal controlling the timing and sending of data, UART relies on the start and stop bits of a UART data frame to signal when to start and stop transmission.
• UART typically has slower data speeds compared to modern networking methods and usually connected as a 1 to 1 communication and all data transmission variables such as sample rate, flow control, data frame size and voltage levels need to agree before connection can be made.
• Most modern microcontroller devices typically have more than one set UART circuity, allowing for multiple UART connections communication to function for multiple devices.

Comparing UART, SPI, I2C, and I3C

A comparison of the UART and SPI communication protocols

A comparison of the I2C and I3C communication protocols

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SparkFun Qwiic Connect

• Rapid system for connecting I2C devices without needing to solder
• Also makes it easier so that data and clock lines don't get reversed
• Over 100 child devices can be daisy-chained from the parent device
• Only 3.3 volt signaling
• Nonstandard board sizes

SparkFun Qwiic connect ecosystem example

Adafruit STEMMA QT Connect

• Rapid prototyping system using a plug standard to eliminate or reduce wiring and soldering time
• Compatible Sensor platforms have voltage level shifting for both 3.3V and 5V
• I2C communication
• Compatible with SparkFun Qwiic
• Compatible with Seeed Grove (via adapter)

Adafruit sensor with two STEMMA QT sockets

Seeed Grove

• Allows plug and play addition of peripherals / modules
• Compatible with many different microcontroller platforms such as Arduino, NodeMCU, and Raspberry Pi
• Set of fixed board sizes for sensor modules/board
• 4 position connectors and 4 conductor cables
• Communication can be analog, I2C, and UART
• Grove shield stacks on top of development board to provide an easy to access set of connectors

Grove based shield for Arduino

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Industrial Sensors

These core receptors for factories and industrial settings are discussed with the Automation Resource Center.

From Industrial Sensors eMagazine

Transportation Sensors

Sensors within automotive and transportation are discussed in the Transportation Applications and Technologies page.

From Transportation Sensors eMagzine

Edge AI Sensors

Smart sensors are discussed within the Edge AI Applications and Technologies page.

From Edge AI eMagazine

Types of Current Sensors

• Hall effect – measure the magnetic field, which is based on the amount of current flowing. This naturally provides galvanic isolation. These can be used for AC and DC current measurement. These generally have less precision, and cost more than shunt based solutions. However, these can be advantageous over shunt based solutions, as they low insertion losses and can handle thousands of amps.
• Shunt based – measures the current through a precision resistor, which the current flows through. These solutions have the highest accuracy, and lower cost. However it does introduce some power loss. Usually not isolated.
• Current transformer – magnetic coupling for measuring AC current with natural galvanic isolation. Excellent for high current AC systems. Gets a lot of use in utility and industrial environments.

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Environmental Sensors

Environmental aspects like temperature and humidity can play a role in the longevity of buildings and electronic components. Heating, ventilation, and air conditioning (HVAC) systems rely on good environmental data for operation.

Temperature Sensors

Temperature Sensors are devices that can measure the heat of a surrounding or distant location and transmit that data to the system. This is often accomplished by taking advantage of how materials change physical and electrical properties in response to heat.

Thermocouples – most common type of temperature sensors due to their self-powered nature and quick response times across a wide range of temperature. Thermocouples work by a physical rule known as the Seebeck effect. When there is a temperature difference between two different conductor materials, the junction produces a voltage differential which can be amplified and measured.

Resistance Temperature Detector (RTD) – a simple sensor that measures the change in resistance of metals the temperature changes. RTDs are usually slower responding than thermocouples which make them poor fits for environments that experience rapid changes.

Thermistors – made from polymer or ceramic material making them cheaper and more easily produced than RTDs or Thermocouples but with the tradeoff of less stability and accuracy. Thermistors generally have larger output signal ranges (therefore need less amplification and filtering). Negative Temperature Coefficient (NTC) thermistor are the most common and widely used thermistor. With NTCs the resistance measure across the device decreases as the temperature increases. Positive Temperature Coefficient (PTC) thermistor exhibit an increase in resistance in response to an increase in temperature. Typically, better for threshold sensing in applications like over-temp detection.

Integrated Circuit (IC) – devices can have several layers of logic including Data Processing that can help these devices achieve more linearity in the measurement. Additionally, the ICs may contain threshold monitoring or alerting capabilities within the device, which may reduce the number of parts needed in a design.

Humidity and Moisture Sensors

Humidity is a measurement of the amount of water vapor in the air. It can affect both human health and machine performance. High humidity can lead to mold and mildew growth. Additionally, high humidity can cause corrosion and electrical shorts. Low humidity can adversely affect human health and increase Electrostatic discharge (ESD) potential for electronic circuits. Humidity can be represented in terms of Relative humidity (RH), which is a percentage representing the current water vapor to amount of water vapor that could be present before condensation occurs at a given temperature. Absolute humidity is the percentage of water vapor present in the air.

Below are methods on how humidity sensors operate:

Capacitive Based – works by measuring changes in capacitance as the dielectric absorbs and releases water based on the surrounding environment. This is most common type of humidity sensor due to low cost, low maintenance, and linearity of the sensor over time. Measures relative humidity.

Resistive Based – typically has two areas of electrically conductive material separated by a nonmetallic layer. As this nonmetallic layer absorbs water from the surrounding air, the resistance decreases allowing more electric current to pass between the two conductive areas. Measures relative humidity.

Thermal Based – made up of two evenly matched thermistors, one exposed to open air and the other in a sealed container. As the exposed thermistor encounters humid air, it changes resistance measurement. The difference in resistance between the two thermistors is directly proportional to the absolute humidity.

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Pressure Sensors

Pressure Sensors are designed to detect the presence or a change in the amount of force per unit of area. This can be measured in liquids such as water, oil, or other chemicals or in gas like the air we breathe.

Pressure sensors main method of operation is by measuring changes in electrical voltages generated by the Piezoelectric effect. The Piezoelectric effect is a property of certain physical materials like quartz crystals, ceramics, and metal alloys to generate an electrical charge when placed under mechanical stress.

There are several ways to measure pressure in both Metric and Imperial measurement systems. When selecting a sensor, be sure that the final choice is compatible with other sensors in the system.

Pressure units:

• Pascal: Metric system unit of measure, defined as 1 Newton of force per square meter
• Bar: levels of pressure individuals may experience, defined as exactly 100,000 Pascals, which is slightly below normal atmospheric pressure at sea level (1.013 bar)
• Pounds per square inch (PSI): more common for Americans and, the Imperial system.

Types of pressure sensors:

Gauge – measures pressure in reference to normal local atmospheric pressure. These sensors have a vent open to normal atmosphere acting as a sensor reference. Any pressure measurement taken would only be in reference to local conditions.

Absolute – measures pressure in relation to an absolute vacuum or zero pressure. By using a vacuum with zero pressure as a measurement reference, all measurements using that reference will be the same regardless of conditions. This allows for stable and consistence results across operating conditions. It also makes these sensors a good choice for altitude, and depth measurement, including indoor navigation.

Differential – measure the difference between two separate pressures, each one connected on a different side of a sensor diagraph. This type of pressure sensor is usually found in systems that need to measure the rate of flow of a gas or liquid and can be useful in detecting when a blockage or leak has occurred in the system.

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Orientation and Presence Sensors

These are sensors that detect objects, motion, and determine the orientation of a system. An example of related system using these sensors is self driving robots, which require a series of orientation and presence sensors to avoid collision and safely navigate a factory floor.

Motion Sensors

Accelerometers – Velocity (meters / second) is the rate of change in position, Acceleration (meters / second2) is the rate of change of velocity. Another way to think of this is, velocity is how fast a car is traveling and acceleration is how fast the car is changing its speed. Acceleration and velocity do not only apply to a car moving in one direction, but it also applies to the turns (change in direction). Accelerometers are therefore sensors that can measure the vibration or acceleration of a system. Many current accelerometers are 3 axis, meaning they can measure acceleration in the X, Y, and Z dimensions. Most electronic accelerometers operate Micro-electromechanical systems (MEMS) measuring changes in capacitance or voltages caused by piezoelectric materials under stress.

Optical Motion Sensors – can use light, usually infrared radiation to detect movements and some of the sensors can determine the direction of the movement. Passive Infrared (PIR) sensors can detect changes in the amount of infrared light that strike the sensor. These sensors are commonly used in security detection or automatic lights that respond when someone enters a room. Pyroelectric sensors are attuned to picking up the infrared radiation associated with heat. Pyroelectric sensors are applied to sensing fire, as well as thermal imagining for people.

Gyroscopes – devices for measuring the rotational changes. Gyroscopes make it possible to sense changes in angular velocity, or rate of turn, measured in degrees per second. The goal for this sensor is to provide feedback so that a system (like an airplane) can determine the rates of change and balance. Electronic gyroscopes with Micro-electromechanical systems (MEMS) sensing are popular due to small size, low power consumption, and accuracy.

Inertial Measurement Units (IMUs) – electronic device that can measure acceleration, orientation, and angular turning rates across all three axes of motion. These devices are based on multi-axes combinations of differing sensor types which often include an accelerometer, a gyroscope, and a magnetometer in the same package.

Optical Sensors

Optical Sensors (also known as Photoelectric Sensors) are devices that can detect objects by use of optical properties. Unlike other sensors that can only detect objects with certain metallic or conductive material composition, optical sensors are able to work with a wide variety of materials such as plastic, glass, wood, and metal. Typically, an optical sensor is a device with two main components: an Emitter usually a LED that can project a beam of light in one direction and a Receiver a phototransistor in a circuit that is able to respond to changing levels of light.

Through beam sensors – a pair of separate devices, one emitter unit that projects the beam of light out and one receiver that receives it. As an object passes through the beam, it interrupts the light path and either reduces or blocks the light beam from the receiving unit. The change in the amount of light at the receiving unit can then trigger the output circuity. A common embodiment of this sensor is the safety beam on garage door opener systems.

Source: Omron Industrial Automation

Retro-reflective sensors – are like through beam sensors but instead of having the emitter and receiver in two separate units, both elements are in the same housing. The light from the emitter element is projected outward towards a reflector which reflects the light back to the receiver element. As an object passes through the light beam, there's a reduced amount of light at the receiver.

Source: Omron Industrial Automation

Diffuse-reflective sensors – have both the Emitter and Receiver in the same package but unlike reflective sensors, the diffuse sensor triggers when light is reflected from the target object back to the receiver element. If the target object can return some light back to the sensor it will trigger making it very flexible in terms of object path and orientation.

Source: Omron Industrial Automation

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Proximity Sensors

Proximity Sensors are devices that can determine the presence or distance of an object without physically contacting the object. There are many different methods of operation ranging from sensors that work with detecting target physical properties to those that work with the sensing environment.

Inductive proximity sensors – detect the presence of conductive (i.e., metal) objects and have a sensing range that is dependent on the type of metal being detected. These sensors operate by using a magnetic field that constantly changes polarity at high frequencies. As a conductive metal target passes through the field generated by the sensor, an eddy current is generated in the target object. That eddy current creates an opposing magnetic field that disrupts the sensor field allowing the change to trigger an output circuit.

Ultrasonic proximity sensors – are sensors that emit a burst of high frequency soundwaves, operating at a higher than the human hearing range. By measuring the time for reflected sound waves to bounce off the target object and return to the receiving sensor, the distance to the target can be determined.

Capacitive proximity sensors – can detect both metallic and non-metallic target substances in form factors such as powder, granulated, liquid, and solid forms. These sensors are much like inductive sensors but instead of measuring a metallic object's inductive property, these work by measuring the changes in capacitance. The sense plate, acting as one half of a capacitor with the target object acting as the other half can detect changes in capacitance which changes in response to physical distance or composition.

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Distance Sensors

Distance ranging technologies use optical and RF-based methods to provide accurate, real-time measurement of an object’s position within an environment. Solutions such as Time-of-Flight (ToF), LiDAR, radar, and Ultra-Wideband (UWB) enable spatial awareness across a wide range of applications, including robotics, transportation, and ranging objects.

Whereas proximity is typically provided a binary output (either within range or outside of range), distance sensors are determining how far to an object.

Time-of-flight (ToF) - enables accurate, real-time distance measurement by calculating the travel time of emitted signals. Great with short range precision measurement.

LiDar - uses laser-based measurements to generate precise, high-resolution set of distance measurements. Great for mapping a space.

Radar – uses RF signals to detect distance, motion, and presence. Great for getting distance readings through obstacles.

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