The Software Side
Different Types of Sensor Communication
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I2C sensor: These types of sensors communicate with the microcontroller using two pure signal wires called CLOCK and DATA. In the case of SHTC3, which has an address 0x70, we set the LSB bit to 1 to configure the sensor to read mode followed by the CBUS address in order to send the signal uniquely to the signal. The sensor provides an acknowledgment and the sensor data can be processed by the microcontroller.
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Analog sensor: These types of sensors communicate with the microcontroller by providing signals which lie in the range of 0V to 5V. The value which corresponds to 5V is 1023. In the case of a pulse sensor, an ambient LED reflects off of blood vessels passing through the finger. The time it takes for the light to return back corresponds to the peaks and depressions caused by the heartbeat.
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Digital sensor: These types of sensors communicate with the environment and return a digital value in terms of binary units. 5V corresponds to 1 and 0V corresponds to 0. Our touch sensor is a digital capacitive sensor that when touched changes the electrical permeability between the capacitor plates and effectively changes the voltage between the plates.
MQTT Protocol
MQTT is a standard messaging protocol for the Internet of Things (IoT). This protocol is designed as a publisher/subscriber messaging paradigm.
In our project, we use the MQTT protocol to transport and connect data between remote devices with minimal network bandwidth using a same topic subscription.
We use the MQTT protocol to send data from the microcontroller to the Node Red dashboard using ATSAMW25 microcontroller's WiFi connection.
