Hardware
Gases PRO Sensor Board
General description
The Waspmote Gases PRO v3 Sensor Board has been designed to monitor environmental parameters such as temperature, humidity, pressure, particle matter in the air (dust) and 16 different types of gases. It allows the inclusion of 6 AFE (Analog Front End) modules at the same time (4 in Plug & Sense!).
An AFE module is composed of one round AFE board and one cylindrical sensor. Each AFE board is ready to manage the installed gas sensor and to perform the conversion from a voltage or current signal to a digital value. Also, an EEPROM (non-volatile memory) stores the basic data for the sensor such as kind of gas sensor, sensitivity or baseline. This allows to the user to plug the AFE module in the available sockets of the Gases PRO Sensor Board and program Waspmote easily.
Each AFE module has been programmed and calibrated for a unique gas sensor. Each AFE module contains the specific calibration parameters for the sensor unit it is attached to, so changing the AFE boards between sensors will cause that the sensor reads wrong values. It can even damage the sensor. So, changing the AFE boards between gas sensors is forbidden. Just do NOT separate the AFE board + sensor couples.
The gases which can be monitored are:
Carbon Monoxide -- CO
Carbon Dioxide -- CO2
Molecular Oxygen -- O2
Ozone -- O3
Nitric Oxide -- NO
Nitric Dioxide -- NO2
Sulfur Dioxide -- SO2
Ammonia -- NH3
Methane and other combustible gases -- CH4
Molecular Hydrogen -- H2
Hydrogen Sulfide -- H2S
Hydrogen Chloride -- HCl
Hydrogen Cyanide -- HCN
Phosphine -- PH3
Ethylene Oxide -- ETO
Chlorine -- Cl2
3-electrode AFE board
General description
This AFE board has been developed to manage a 3-electrode electrochemical gas sensor, store the specific parameters of the sensor in its EEPROM (non-volatile memory) and perform a measure using its ADC.
The gases which use the 3-electrode AFE board are:
Molecular Oxygen -- O2
Ammonia -- NH3
Molecular Hydrogen -- H2
Hydrogen Sulfide -- H2S
Hydrogen Chloride -- HCl
Hydrogen Cyanide -- HCN
Phosphine -- PH3
Ethylene Oxide -- ETO
Chlorine -- Cl2
As the EEPROM stores the parametric characteristics of a specific sensor, AFE boards must NOT be interchanged between sensors.
How to plug
To plug the 3-electrode AFE board into the Gases PRO Sensor Board, white marks must be facing to the right side of the board.
Be careful connecting the 3-electrode AFE board. If the AFE board is connected wrong, the sensor and the AFE board could be damaged.
4-electrode AFE board
General description
This AFE board has been developed to manage a 4-electrode electrochemical gas sensor, store the specific parameters of the sensor and the board into its EEPROM (non-volatile memory) and perform a measure using its ADC.
A 4-electrode electrochemical gas sensor works as a 3-electrode gas sensor. Counter, reference and working electrode are used normally to set the bias voltage and generate the current. The fourth electrode, commonly called auxiliary electrode, works as an extra working electrode and it is used to compensate the variations produced by the temperature in the baseline current and get a better gas accuracy. The compensation will be performed automatically by the API library.
The gases which use 4-electrode AFE board are:
Ozone -- O3
Carbon Monoxide for low concentrations -- CO
Nitric Oxide for low concentrations - NO
Nitric Dioxide high accuracy -- NO2
Sulfur Dioxide high accuracy -- SO2
How to plug
To plug the 4-electrode AFE board into the Gases PRO Sensor Board the white marks must be facing to the right side of the board.
Be careful connecting the 4-electrode AFE board. If the AFE board is connected wrong, the sensor and the AFE board could be damaged.
Pellistor/NDIR AFE board
General description
The pellistor/NDIR AFE board has been developed to manage a pellistor gas sensor or an NDIR sensor, store the specific parameters of the sensor and the board into the EEPROM (non-volatile memory) and perform a measure using an ADC.
The gases which use pellistor AFE board are:
Methane and other combustible gases -- CH4
Carbon Dioxide -- CO2
How to plug
To plug the pellistor/NDIR AFE board into the Gases PRO Sensor Board the white marks must be facing inside of the board.
Be careful connecting the pellistor/NDIR AFE board. If the AFE board is connected wrong, the sensor and the AFE board could be damaged.
Advices to plug in AFE on PCB sensors
Before using the sensors, you must keep in mind how to plug and initialize it properly
The Images pointed with a stylus pen, it shows on the surface of both PCB a serigraph with a white dash mark. for proper operation marks of smart cities PCB and Gas Sensor PCB should be in opposite side from each other when connector is plugged.
Specifications
All the available sensors are connected to Waspmote through the "mother board", the Gases PRO Sensor Board.
Weight: 20 g
Dimensions: 73.5 x 51 x 22 mm (without sensors)
Temperature range: [-20 ºC, 65 ºC]
Sensors compatibility:
The CH4 and Combustible Gases Sensor AFE, and the CO2 Sensor AFE can only use socket 1, so the total number of these sensors per board is limited to 1
The central socket is reserved for the BME280 sensor (Temperature, humidity and pressure Sensor)
The rest of the sensors can use all sockets
Electrical characteristics
Board power voltage: 3.3 V and 5 V
Sensor power voltage: Gas sensors and BME280, 3.3 V. Particles-dust sensor, 3.3 V and 5 V
Maximum admitted current (continuous): 200 mA
Maximum admitted current (peak): 400 mA
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