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CozIR

-LP3 Evaluation Board User Guide

Revision 1.5: 15 December 2020

Page | 21 For regular updates, go to https://gassensing.co.uk

ZERO-POINT SETTING THE SENSOR

There are a several methods available to the user to set the zero point of the sensor. In all cases, the

best zero is obtained when the gas concentration is stable, and the sensor is at a stable temperature.

Note the zero-point settings are not cumulative and only the latest zero-point setting is effective. For

example, there is no benefit in zeroing in nitrogen, and then zeroing in a calibration gas. The sensor

will store only the latest zero point.

ZERO IN NITROGEN

Place the sensor in nitrogen gas and allow time for the sensor to stabilise and the gas to be fully

diffused into the sensor. Click on ‘Nitrogen’. The sensor will be zeroed assuming a 0ppm CO

environment.

ZERO IN AMBIENT CONDITIONS

If there is no calibration gas or nitrogen available, the sensor zero-point can be set in fresh air.

Ambient CO

concentrations in fresh air are typically 400ppm. Place the sensor in a fresh air

environment and allow time for the sensor temperature to stabilise, and for the fresh air to be fully

Содержание CozIR-LP3

Страница 1: ...CozIR LP3 Evaluation Board User Guide Revision 1 5 15 December 2020 Page 1 For regular updates go to https gassensing co uk CozIR LP3 Evaluation Board User Guide ...

Страница 2: ...R POWER CONSUMPTION MEASUREMENT 12 ENVIRONMENTAL CONDITION MONITORING 12 EVALUATION BOARD BUTTONS JUMPERS AND LED INDICATORS 12 SOFTWARE USER INTERFACE 13 RUNNING THE SOFTWARE 14 SENSOR SELECTION 15 CO2 SENSOR MEASUREMENT MODE 16 UART Communications Mode 17 I2 C Communications Mode 17 OTHER ENVIRONMENTAL SENSORS 18 GRAPHING SENSOR DATA 20 ZERO POINT SETTING THE SENSOR 21 ZERO IN NITROGEN 21 ZERO I...

Страница 3: ...or regular updates go to https gassensing co uk DATA DISPLAY 27 DATALOGGING 29 TERMINAL VIEW 31 TERMINAL VIEW UART READ 32 TERMINAL VIEW UART WRITE 33 TERMINAL VIEW I2 C WRITE 34 TERMINAL VIEW I2 C READ 35 MECHANICAL DIAGRAM 37 IMPORTANT NOTICE 38 ADDRESS 38 REVISION HISTORY 39 ...

Страница 4: ...s provides the user with a graphical user interface to all the main functions of the sensor as well as a terminal mode allowing the user to write and read data directly from the sensor registers As well as evaluating the CO2 sensor the software application allows the user to monitor and store other environmental conditions such as pressure relative humidity and temperature The evaluation board als...

Страница 5: ...rs VCP htm Choose VCP Drivers and select the correct driver for your operating system SOFTWARE INSTALLATION The GSS evaluation board software is available direct from the GSS web site Download the zip file to your computer Unzip and click on Setup exe and follow the instructions on the screen INSTALLING THE SENSOR The sensor needs to be connected to the board Rotate the fixing cams out of the way ...

Страница 6: ...omponents The evaluation board consists of a USB interface device which connects to an on board micro controller The on board microcontroller connects to the sensor using either its UART or I2 C interface The interface mode is user selectable The microcontroller also interfaces to the environmental monitoring sensors The board comes with temperature humidity and pressure sensors ...

Страница 7: ...CozIR LP3 Evaluation Board User Guide Revision 1 5 15 December 2020 Page 7 For regular updates go to https gassensing co uk Figure 2 Top Side Evaluation Board Figure 3 Bottom Side Evaluation Board ...

Страница 8: ...set the switches to OFF Power supply connections to the sensor are described in the following section The sensor switch connections on the DIP switches are listed below SWITCH POSITION NAME TYPE DESCRIPTION 1 Rx_In Digital Input UART Receive Input 2 Tx_Out Digital Output UART Transmit Output 3 NC Unused Do not connect For internal use only 4 PWR_ON Digital Input Sensor Power On Enable pin Power on...

Страница 9: ...pply barrel plug This drives a low noise low drop out LDO regulator which supplies the sensor via a FET switch The state of the FET switch is controlled by the state of the PWR_On pin accessed via connector J5 pin 4 The LDO regulator provides a stable 3 3V output to the sensor To enable this mode of operation switch S1 should be set to external power EXT PWR The LDO input voltage range is a nomina...

Страница 10: ...eed to be configured Connector Jumper Setting Sensor Connection J5 pin 1 Connect to external GND GND J5 pin 2 Connect to external VDD VDD PL2 Remove jumper Isolates sensor from rest of the evaluation board S2 Set to OFF Isolates LDO from sensor The evaluation board has pull up resistors for the I2 C serial data input output lines in each of these modes They pull up to either the on board 3 3V supp...

Страница 11: ...ut UART Transmit Output 4 Rx_In Digital Input UART Receive Input J4 PIN NAME TYPE DESCRIPTION 1 ALARM Digital Output Alarm Output 2 READY Digital Output Data ready pin Pulsed high when data ready 3 PWM_RS485 Digital Output PWM Output 4 I2C_ENABLE Digital Input Set low for I2 C interface mode Leave floating to select UART interface mode Pin status detected at power on J5 PIN NAME TYPE DESCRIPTION 1...

Страница 12: ...sure relative humidity temperature and pressure in real time These functions operate independently of the CO2 sensor The application software displays and can store these conditions The evaluation board must be powered either via the USB interface method 2 or the external power supply method 1 EVALUATION BOARD BUTTONS JUMPERS AND LED INDICATORS BUTTON DESCRIPTION S1 USB power or external power S2 ...

Страница 13: ... 2020 Page 13 For regular updates go to https gassensing co uk SOFTWARE USER INTERFACE All the main sensor and evaluation board functions are controlled through a single user interface displayed above Hovering over a button will display the tips for that function ...

Страница 14: ...he Start Menu Look for the filename GSS Customer Evaluation Board The opening screen is below To connect to the sensor select the correct COM port from the drop down Connection list then click the CONNECT button The drop down list will only show ports with active devices attached If you do not know the appropriate port select device manager on your PC select Ports and unplug the SEB and then plug ...

Страница 15: ...nge CO2 ppm of the sensor The sensor should automatically start to take CO2 measurements after 2 3 seconds These measurements are shown graphically in the middle of the screen The default operating mode of the sensor on the evaluation board is set to continuous measurement using the UART interface Additionally the power LED1 will illuminate green showing the sensor evaluation board is running ...

Страница 16: ...d the digital interface mode Select the Mode using one of the 3 buttons Stopped All measurements are stopped The sensor is still capable of reading and writing to the control interface Some commands are not be available in this mode please see the datasheet Continuous Measurements running continuously and reading sent at a fixed rate of 2 per second Polling Measurements running in the background R...

Страница 17: ...r value when Manual Measurement is clicked To take readings at a scheduled time period click on Polling and change Measurement Time to Measure every 5 seconds and click on Set This allows the user to pre set their own read period The user interface in the lower centre of the screen will update the CO2 sensor value at the scheduled period When in UART mode LED 2 will flash green momentarily to show...

Страница 18: ...dependently of the CO2 sensor read period For manual readings click Manual Measurement Manual readings can be taken for each sensor including the CO2 sensor by clicking on the relevant button The user interface in the lower centre of the screen will update each sensor value when Manual Measurement is clicked Alternatively the sensors can be programmed to take readings continuously at the rate set ...

Страница 19: ...ction behaves slightly differently to the other sensors The Average Current displayed in the lower centre of the screen is the average current consumed by the sensor over a single reading period If the sensor is set to Continuous Mode or Polling Mode where the sensor is taking a measurement every 0 5s the average current is defined over the 0 5s period ...

Страница 20: ...gs in the case of the CO2 sensor or by the Temperature Humidity and Pressure Settings When the current graph is enabled the evaluation board will accurately measure and graph the current the sensor uses over the measurement period This can be updated by clicking the update button or manually polling using the Current button The key activity period is displayed and the average current per reading c...

Страница 21: ...le there is no benefit in zeroing in nitrogen and then zeroing in a calibration gas The sensor will store only the latest zero point ZERO IN NITROGEN Place the sensor in nitrogen gas and allow time for the sensor to stabilise and the gas to be fully diffused into the sensor Click on Nitrogen The sensor will be zeroed assuming a 0ppm CO2 environment ZERO IN AMBIENT CONDITIONS If there is no calibra...

Страница 22: ... into the sensor Set the CO2 concentration value to the appropriate value by writing the value in the set to box Click on Known Gas AUTO ZERO FUNCTION The sensor has a built in auto zeroing function To function correctly the sensor must be exposed to typical background fresh air levels 400ppm at least once during the auto zero period The auto zero function uses the information gathered during thes...

Страница 23: ...e the background ambient level used for auto zeroing The value is stored in the sensor Typically it is set to the same value as the ambient value but it can also be set at a different level if desired To write a different fresh air CO2 concentration value to the sensor used for auto zeroing the command must be sent to the sensor manually using the software terminal mode For more details on how to ...

Страница 24: ...sor will vary from the nominal output if the mean barometric pressure is different from the calibration setting It is possible to configure the sensor to correct for this effect by writing the actual or reference mean barometric pressure in mbar to the sensor This can be done as part of the initial set up process or updated at any time during use Write the decimal value in mbar into the dialogue b...

Страница 25: ...https gassensing co uk DIGITAL FILTER SETTING CO2 measurements are filtered by default The digital filter value can be varied between 1 256 If set to 1 there is no digital filtering The default value is 16 Reducing the digital filtering increases sensor response rate at the expense of measurement noise ...

Страница 26: ... uk SENSOR COMMUNICATIONS The sensor has two control interface modes To ensure the sensor behaviour is representative of real world use the evaluation board microprocessor will communicate with the sensor in either UART or I2 C mode dependent on this setting To set the interface mode click on the appropriate dialogue box ...

Страница 27: ...ta Type Description Units Sensor ID No Unique sensor ID N A CO2 CO2concentration ppm Temperature Ambient temperature C Pressure Ambient pressure mbar Average Current Current drawn by the sensor in a measurement cycle see description for more details uA Relative Humidity Ambient relative humidity RH Absolute Humidity Ambient absolute humidity grams per cubic metre This data is updated depending on ...

Страница 28: ...on Units Mode Measurement mode Poll Period Measurement update period Seconds Filter Digital filter setting Decimal Last Zero Value Value used to re zero the sensor ppm Pressure Comp Pressure value used by CO2 sensor mbar Hours Ran Number of hours sensor has been powered up Decimal This data is static and represents the configuration of the CO2 sensor ...

Страница 29: ...ember 2020 Page 29 For regular updates go to https gassensing co uk DATALOGGING CO2and other sensor data can be recorded To initiate the recording process click Record To stop the recording process click Stop Clicking on Record brings up the following screen ...

Страница 30: ...7674 with different data recorded at different rates Recorded by GSS Sensor Evaluation Board 16 11 2020 13 02 437674 Timestamp CO2 ppm Temperature C Pressure mB RH AH g m 3 16 11 20 13 02 53 729 460 16 11 20 13 02 54 834 16 11 20 13 02 55 218 453 16 11 20 13 02 56 338 16 11 20 13 02 56 723 459 16 11 20 13 02 56 739 23 92 1002 33 43 64 9 45 16 11 20 13 02 57 827 16 11 20 13 02 58 228 466 16 11 20 1...

Страница 31: ...AL VIEW Access to all CO2 sensor functions and register settings are available to the user using the Terminal View Terminal View allows the user to read and write directly to the CO2 sensor In the Terminal View the user can reset the sensor if required by clicking on the Reset button This toggles the state of the sensor PWR_ON pin ...

Страница 32: ...nsure that UART Comms has been selected under the Communications menu To read a value write the command into the dialogue box and click Send In this example the Command is shown It automatically returns the information shown in the Terminal View By pressing the Debug button a command is sent to return the sensor settings as above This returns information on the state of the sensor including sensor...

Страница 33: ...TE Write the command into the dialogue box and click Send In this example the X Command is shown X is the command to zero the sensor in a known gas concentration in this case 1000ppm Sending a command followed by an integer X 1000 in this case will write the value into the appropriate register The sensor will respond with a variable decimal value ...

Страница 34: ...he Communications menu To write to an I2 C register the instruction must be formatted correctly Writes are formatted as wr followed by the number of bits to write followed by the register number in decimal followed by the decimal value to write to the register For example wr8 5 1 will write the value 1 as an 8 bit word to register 5 which will zero the sensor in ambient conditions as per the datas...

Страница 35: ...ensing co uk TERMINAL VIEW I2 C READ To read from an I2C register the instruction is formatted as rd followed by the number of bits to read as noted in the datasheet followed by the register number in decimal For example rd16 2 will read 16 bits from register 2 which in this case will return the CO2 value in ppm ...

Страница 36: ...ng co uk The in the I2 C commands denotes to the evaluation board that a special command that must be pre processed before passing on to the sensor If the interface is set to I2 C mode and if the is missing the evaluation board assume the command is a UART command and sending it on to the sensor will return a timeout ...

Страница 37: ...CozIR LP3 Evaluation Board User Guide Revision 1 5 15 December 2020 Page 37 For regular updates go to https gassensing co uk MECHANICAL DIAGRAM ...

Страница 38: ...ended for use in life support systems appliances nuclear systems or systems where malfunction can reasonably be expected to result in personal injury death or severe property or environmental damage Any use of products by the customer for such purposes is at the customer s own risk GSS does not grant any licence express or implied under any patent right copyright mask work right or other intellect...

Страница 39: ...ps gassensing co uk REVISION HISTORY DATE RELEASE DESCRIPTION OF CHANGES PAGES 21 07 2020 1 0 First revision All 20 10 2020 1 1 Full first draft All 13 11 2020 1 2 Updates All 25 11 2020 1 3 Final UI All 5 12 2020 1 4 First formal release All 15 15 2020 1 5 Mechanical Diagram and Pin Out Description Pg 37 ...

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