Sensors
The current version of the BEVO Beacon employs 5 different Indoor Air quality (IAQ) sensors, one light sensor, a real-time clock, and an OLED display. The details of each of these sensors in addition to instructions on how to connect them are given below.
The carbon dioxide (CO2) sensor that we use on the BEVO Beacon is the Sensirion SCD30 sensor that has now been deprecated in favor of a newer model. The pinout for the sensor is shown below. We use the the first four pins (VDD, GND, SCL, SDA) and the last pin (SEL) to wire the sensor to the PCB. If connected properly, the RPI should detect I2C address 61.
The sensor we use to detect different sizes of Particulate Matter (PM) is the Sensirion SPS30. The SPS30 sensor module does include pins or locations for pins like the CO@ sensor, but rather requires a connection where the other end can either be directly soldered to the PCB or male/female headers can be attached which then plug into the PCB (the latter is what is done on later versions of the BEVO Beacon).
Total Volatile Organic Compounds (TVOCs) are measured by the SGP30 sensor on the Sensirion SVM30 module which includes a T/RH sensor that we do not use. Similar, to the SPS30, the SVM30 module does not come with traditional pins so we use this connection with headers attached to the other end which plug into slots on the PCB.
We use the digital gas sensor from SPEC to measure nitrogen dioxide (NO2). The SPEC sensors require a serial connection. Rather than directly wire the sensors to the PCB, we use the USB-A connection that comes with each of the sensors and connect the sensors directly the RPi. However, the pinout is still shown below.
We no longer use the NO2 module on the latest version of the BEVO Beacon for two reasons: (1) the resolution on the sensor is 20 ppb which is too low for indoor conditions and (2) we swapped the Raspberry Pi 3B+ for a Raspberry Pi Zero which only includes one USB port which we use for the carbon monoxide sensor.
We use the digital gas sensor from SPEC to measure carbon monoxide (CO). Again, we connect the SPEC DGS-CO sensor directly to the RPi through a USB-A connection, but the pinout is provided again.
To measure light, we use the TSL2591 sensor created by Adafruit. The sensor and description of pins is given below. For our purposes, we simply use the GND, VDD, SCL, and SDA pins and leave the rest floating. The pins are clearly labeled on the sensor and technical readouts are not given here.
