SprintIR®‐W
High Speed CO2 Sensor
DESCRIPTION
FEATURES
The SprintIR®‐W is a high flow through NDIR
CO2 sensor using state‐of‐the‐art solid‐state
LED optical technology. The low power LEDs
are manufactured in‐house, giving GSS
complete control of the CO2 sensor signal chain.
The SprintIR®‐W is designed for applications
that need high response time and high‐speed
measurement capability. The SprintIR®‐W is
takes 20 readings per second, making it ideal
for equipment that needs real‐time CO2 gas
analysis or monitoring.
The sensor is available in multiple versions,
capable of measuring CO2 levels up to 100%
concentration.
20 readings per second
High flow throughput capability
Custom flow adaptor options
70ppm typical measurement accuracy
Measurement range up to 100%
Solid state NDIR LED optical technology
UART control and data interface
Built‐in auto‐zeroing
APPLICATIONS
Healthcare
Food Packaging
Sport Science
CO₂ Fire Suppression Deployment
VDD
GND
BLOCK DIAGRAM
TEMP
SENSOR
RH
SENSOR
ANALOGUE_OUTPUT*
DAC
LED
DRIVER
LED
CO2
MEASUREMENT
CHAMBER
uC
DSP
ADC
RECEIVER
PD
CONTROL INTERFACE
Rx_In
Tx_Out
FRESH_AIR_ZERO
NITROGEN_ZERO
PMU
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SprintIR®‐W
High Speed CO2 Sensor
TABLE OF CONTENTS
DESCRIPTION ........................................................................................................................................... 1
FEATURES ................................................................................................................................................ 1
APPLICATIONS ......................................................................................................................................... 1
BLOCK DIAGRAM ..................................................................................................................................... 1
ORDERING INFORMATION ...................................................................................................................... 4
PACKAGE DRAWING: SprintIR®‐W WITH FLOW PORT ADAPTOR ........................................................... 5
PACKAGE DRAWING: SprintIR®‐W WITH MEMBRANE COVER ............................................................... 6
PIN‐OUT DESCRIPTION: SprintIR®‐W (Either Version) ............................................................................ 7
ABSOLUTE MAXIMUM RATINGS ............................................................................................................. 8
CO2 2 PERFORMANCE CHARACTERISTICS ............................................................................................... 9
HUMIDTY PERFORMANCE CHARACTERISTICS ‐ SprintIR®‐W Option .................................................... 10
TEMPERATURE PERFORMANCE CHARACTERISTICS ‐ SprintIR®‐W Option ........................................... 10
CO2 ANALOGUE OUTPUT PERFORMANCE CHARACTERISTICS – SprintIR®‐W Option ........................... 10
ELECTRICAL CHARACTERISTICS ............................................................................................................. 11
POWER CONSUMPTION ‐ SprintIR®‐W ................................................................................................. 11
INTERFACE TIMING – NITROGEN_ZERO and FRESH_AIR_ZERO ........................................................... 12
RESPONSE TIME, FLOW RATE AND MEASUREMENT RATE ‐ SprintIR®‐W ............................................ 13
METHOD OF OPERATION ...................................................................................................................... 14
MODE 0 COMMAND MODE .................................................................................................................. 14
MODE 1 STREAMING MODE ................................................................................................................. 14
MODE 2 POLLING MODE ....................................................................................................................... 14
DIGITAL FILTER ...................................................................................................................................... 15
ZERO POINT SETTING ............................................................................................................................ 17
ZERO IN A KNOWN GAS CONCENTRATION ........................................................................................... 17
ZERO IN NITROGEN ............................................................................................................................... 17
ZERO IN FRESH AIR ................................................................................................................................ 17
ZERO POINT ADJUSTMENT .................................................................................................................... 17
AUTO‐ZERO FUNCTION ......................................................................................................................... 18
AUTO‐ZERO INTERVALS ......................................................................................................................... 18
AUTO‐ZERO SETTINGS ........................................................................................................................... 18
PRESSURE AND CONCENTRATION LEVEL COMPENSATION .................................................................. 19
ALTITUDE COMPENSATION TABLE ........................................................................................................ 19
CONTROL INTERFACE ............................................................................................................................ 21
CONTROL INTERFACE TIMING ‐ UART MODE ....................................................................................... 21
UART COMMAND PROTOCOL ............................................................................................................... 21
UART OPERATION ................................................................................................................................. 21
UART INTERFACE SUMMARY ................................................................................................................ 22
CO2 LEVEL MEASUREMENT VALUE ‐ Z INFORMATION (0x5A) .............................................................. 24
CO2 LEVEL MEASUREMENT VALUE ‐ z INFORMATION (0x7A) .............................................................. 24
‘.’ COMMAND (0x2E) ............................................................................................................................. 24
TEMPERATURE MEASUREMENT VALUE ‐ SprintIR®‐W Option ............................................................. 25
HUMIDITY MEASUREMENT VALUE ‐ SprintIR®‐W Option .................................................................... 25
K COMMAND ......................................................................................................................................... 27
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SprintIR®‐W
High Speed CO2 Sensor
K COMMAND (0x4B) ......................................................................................................................... 27
DIGITAL FILTER COMMANDS ................................................................................................................ 27
A COMMAND (0x41) ......................................................................................................................... 27
a COMMAND (0x61) .......................................................................................................................... 27
ZERO POINT SETTING COMMANDS ...................................................................................................... 28
F COMMAND (0x46) .......................................................................................................................... 28
G COMMAND (0x47) ......................................................................................................................... 29
U COMMAND (0x55) ......................................................................................................................... 29
u COMMAND (0x75) ......................................................................................................................... 29
X COMMAND (0x58) ......................................................................................................................... 29
P COMMAND ‐ CO2 Level for Auto‐Zeroing ...................................................................................... 29
P COMMAND – CO2 Level for Zero‐Point Setting .............................................................................. 30
AUTO‐ZEROING INTERVALS .................................................................................................................. 31
@ COMMAND (0x2E) ........................................................................................................................ 31
PRESSURE AND CONCENTRATION COMPENSATION ............................................................................ 32
S COMMAND (0x53) .......................................................................................................................... 32
s COMMAND (0x73) .......................................................................................................................... 32
MEASUREMENT DATA OUTPUTS .......................................................................................................... 33
M COMMAND ................................................................................................................................... 33
Q COMMAND .................................................................................................................................... 33
SERIAL NUMBER AND FIRMWARE VERSION ......................................................................................... 34
CONNECTION DIAGRAM FOR UART INTERFACE ................................................................................... 35
IMPORTANT NOTICE ............................................................................................................................. 36
ADDRESS ............................................................................................................................................... 36
REVISION HISTORY ................................................................................................................................ 37
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SprintIR®‐W
High Speed CO2 Sensor
ORDERING INFORMATION
SPRINTIR‐W‐X‐XX‐X
X
5
20
60
100
Measurement Range
0‐5%
0‐20%
0‐60%
0‐100%
X
H
Blank
Temperature and RH
Included
Not included
X
CO2 Voltage Output
V
Blank
Included
Not included
X
Flow Adaptor
F
X
Included
Not included, membrane
only
Notes:
1. Sensors are shipped individually
2. Custom flow through adaptors are available, contact GSS for options
See separate data sheet for SprintIR®‐W evaluation kit options.
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Production Data, Revision 4.2, June 2020
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SprintIR®‐W
High Speed CO2 Sensor
PACKAGE DRAWING: SprintIR®‐W WITH FLOW PORT ADAPTOR
Top View
Weight = ~7g
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SprintIR®‐W
High Speed CO2 Sensor
PACKAGE DRAWING: SprintIR®‐W WITH MEMBRANE COVER
Top View
Weight = ~6g
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Production Data, Revision 4.2, June 2020
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SprintIR®‐W
High Speed CO2 Sensor
PIN‐OUT DESCRIPTION: SprintIR®‐W (Either Version)
PIN
1
2
3
4
5
6
7
8
NAME
GND
NC
VDD
GND
Rx_In
GND
Tx_Out
NITROGEN_ZERO
TYPE
Supply
Unused
Supply
Supply
Digital Input
Supply
Digital Output
Digital Input
9
10
ANALOGUE_OUTPUT Analogue Output
FRESH_AIR_ZERO
Digital Input
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DESCRIPTION
Sensor ground
Do Not Connect
Sensor supply voltage
Sensor ground
UART Receive Input
Sensor ground
UART Transmit Output
Set low to initiate a Zero in Nitrogen Setting
Cycle
CO2 Level (Optional)
Set low to initiate a Zero in Fresh Air Setting
Cycle
Production Data, Revision 4.2, June 2020
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SprintIR®‐W
High Speed CO2 Sensor
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are stress ratings only. Permanent damage to the SprintIR®‐W may be
caused by continuously operating at or beyond these limits. The SprintIR®‐W functional operating
limits and guaranteed performance specifications are given at the test conditions specified.
ESD Sensitive Device. This sensor uses ESD sensitive components. It is
therefore generically susceptible to damage from excessive static voltages.
Proper ESD precautions must be taken during handling and storage of this
device.
CONDITION
Supply Voltages
Voltage Range Digital Inputs
Operating Temperature Range (Ta)
‐ Standard
Storage Temperature Range
Humidity Range (RH)
Operating Ambient Pressure Range
MIN
‐0.3V
GND ‐0.3V
0°C
‐40°C
0
500mbar
MAX
+6.0V
5V
+50°C
+70°C
95%
2bar
RECOMMENDED OPERATING CONDITIONS
PARAMETER
Supply
Ground
SYMBOL
VDD
GND
MIN
3.25
TYP
3.3
0
MAX
5.5
UNIT
V
V
MECHANICAL SEALING
CONDITION
Working Pressure1
Burst Pressure2
MIN
0.3bar
2bar
MAX
Test Conditions Unless Otherwise Specified
1.
2.
The mechanical sealing between the flow adaptor and sensor housing is tested by pressurising the gas chamber to 0.3bar. The
pressure reading must not drop by more than 1mbar within 30 seconds
Guaranteed by design, not tested
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SprintIR®‐W
High Speed CO2 Sensor
CO2 2 PERFORMANCE CHARACTERISTICS
Test Conditions Unless Otherwise Specified
VDD = 3.3V, GND = 0V. CO2 = 450ppm, RH = 0% non‐condensing, T= 25°C, Pressure = 1013mbar, Flow Rate = 0.2l/minute
PARAMETER
CO2 measurement
range
Accuracy
SYMBOL TEST
CONDITIONS
(Peak‐Peak) 0‐60%
Accuracy
(Peak‐Peak) 0‐100%
CO2 RMS Noise
Time to Valid
Measurement
After Power‐On
Response Time
Repeatability
Current
Consumption
MIN
TYP
MAX
UNIT
0
5
0
20
0
60
%
%
%
%
ppm
ppm
0
100
@25°C
±70, +5%
0°C to +50°C, after
auto‐zero @25°C
@25°C
±70, +5%
+~0.1% per
°C
±300, +5%
0°C to +50°C, after
auto‐zero @25°C
Digital filter setting 16
Digital filter setting
16, dependent on
digital filter setting
1.0
1.2
ppm
secs
From 0ppm to T90
default settings,
limited @ 0.2l/min
@25°C, 0‐60%
20
ms
±70, +5%
@25°C, 0‐100%
±300, +5%
Peak current when
sampling
Peak at turn‐on
35
ppm
ppm
mA
SLEEP Mode (K2
polling)
ppm
ppm
±300, +5%,
+~0.1% per
°C
0
40
0.01
mA
mA
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SprintIR®‐W
High Speed CO2 Sensor
HUMIDTY PERFORMANCE CHARACTERISTICS ‐ SprintIR®‐W Option
PARAMETER
SYMBOL TEST
CONDITIONS
Humidity
measurement
range
Accuracy
Repeatability
Response time
Accuracy drift
MIN
TYP
MAX
UNIT
0
100
%
@25°C
±3
% RH
@25°C
±1
10
0.03
%
secs
%/Yr
0‐50%, @25°C
CO2 ANALOGUE OUTPUT PERFORMANCE CHARACTERISTICS – SprintIR®‐W Option
PARAMETER
Output voltage
range1, 2
SYMBOL
TEST
CONDITIONS
ANALOGUE_OUTPUT
CO2 level
0‐5%
0‐20%
0‐60%
0‐100%
Repeatability
Response time
@25°C, 0‐60%
@25°C, 0‐100%
From 0ppm to T50
default settings
MIN
TYP
MAX
0
VDD
66
16.5
5.5
3.3
±0.1
±0.1
0.5
UNIT
V
uV/ppm
uV/ppm
uV/ppm
uV/ppm
%
%
secs
Notes
1. The output CO2 accuracy is degraded where ANALOGUE_OUTPUT VDD–50mV
2. ANALOGUE_OUTPUT accuracy specified with a resistive loading @ >100Kohm
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SprintIR®‐W
High Speed CO2 Sensor
ELECTRICAL CHARACTERISTICS
PARAMETER
SYMBOL TEST
CONDITIONS
Digital Input/Output
Input HIGH Level
Input LOW Level
Output HIGH Level
Output LOW Level
IOH = +1mA
IOL = ‐1mA
MIN
TYP
MAX
UNIT
1.8
2.6
1.0
3.0
0.4
V
V
V
V
POWER CONSUMPTION ‐ SprintIR®‐W
Test Conditions Unless Otherwise Specified
VDD = 3.3V, GND = 0V. CO2 = 450ppm, RH = 0% non‐condensing, T= 25°C, Pressure = 1013mbar, Flow Rate = 0.2l/minute
SETTING
SYMBOL TEST CONDITIONS
Active, K0 SLEEP
mode, no
measurement
Active, K1 mode
whilst taking
measurements
Additional Power
with RH active
Additional Power
with T active
Additional Power
with CO2 active
V
3.3
I (mA)
0.01
Total
Power
mW
0.03
Default settings
3.3
9
30
RH measurement on
3.3
0.05
0.2
Temperature
measurement on
With analogue CO2 output
3.3
0.05
0.2
3.3
0.02
0.1
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VDD
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SprintIR®‐W
High Speed CO2 Sensor
INTERFACE TIMING – NITROGEN_ZERO and FRESH_AIR_ZERO
VDD
t2
t1
NITROGEN_ZERO
t3
CONTROL
INTERFACE
PARAMETER
Power On to NITROGEN_ZERO
Ready
NITROGEN_ZERO Low Pulse‐Width
Control Interface Setup Time
SYMBOL
t1
MIN
300
TYP
MAX
UNIT
ms
t2
t3
3
600
s
ns
The timing for FRESH_AIR_ZERO is identical to NITROGEN_ZERO.
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SprintIR®‐W
High Speed CO2 Sensor
RESPONSE TIME, FLOW RATE AND MEASUREMENT RATE ‐ SprintIR®‐W
The SprintIR®‐W response time is dependent on several interrelated factors.
Measurement Rate
The measurement rate is fixed at 20 readings per second.
Gas Exchange Rate
The most important factor is the gas exchange rate. This is the amount of time it takes for the gas to
enter the CO2 measurement chamber, measured, and then replaced. The sensor has a gas
measurement chamber volume of approximately 2.8ml. As a general rule of thumb, to properly
exchange the gas in the chamber, there needs to be a x5 volume of gas passed through the sensor.
Therefore, approximately 14ml of gas needs to flow through the sensor for each reading.
𝑴𝒂𝒙 𝑭𝒍𝒐𝒘 𝑹𝒂𝒕𝒆 𝒍/𝒎𝒊𝒏
𝟐𝟎 𝒓𝒆𝒂𝒅𝒊𝒏𝒈/𝒔 ∗ 𝟔𝟎𝒔 ∗ 𝟏𝟒𝒎𝒍
𝟏𝟎𝟎𝟎
Digital Filter Setting
The sensor outputs both filtered and raw unfiltered CO2 readings. If the filtered measurement data is
used, the read rate will also depend on the filter setting or the algorithm to process the raw data.
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SprintIR®‐W
High Speed CO2 Sensor
METHOD OF OPERATION
After power is applied to the SprintIR®‐W, the sensor will automatically start to take CO2
measurements using the Mode 1 default settings, where the sensor is pre‐programmed to send CO2
measurement data at 20 readings per second.
The measurement rate is fixed at 20 readings per second at a fixed 9600 baud rate. The sensor will
return the previous CO2 measurement results if the user requests more frequent measurements.
The SprintIR®‐W has 3 potential modes of operation.
MODE 0 COMMAND MODE
In this mode, the sensor is in a SLEEP mode, waiting for commands. No measurements are made.
There is no latency in command responses. All commands that report measurements or alter the
zero‐point settings are disabled in Mode 0. Mode 0 is NOT retained after power cycling.
MODE 1 STREAMING MODE
This is the factory default setting. Measurements are reported twice per second. Commands are
processed when received, except during measurement activity, so there may be a time delay of up
to 10ms in responding to commands.
MODE 2 POLLING MODE
In polling mode, the sensor only reports readings when requested. The sensor will continue to take
measurements in the background, but the output stream is suppressed until data is requested. The
sensor will always power up in streaming or polling mode, whichever mode was used before the
power cycle.
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SprintIR®‐W
High Speed CO2 Sensor
DIGITAL FILTER
The CO2 gas chamber is illuminated with a nominal 4.25um wavelength LED and the signal received
using a photodiode. The signal from the photodiode is processed and filtered by the sensor to
remove noise and provide an accurate CO2 reading. High frequency noise coming from the sampling
process is removed using a proprietary lowpass filter. The digital filter setting can be varied,
allowing the user to reduce measurement noise at the expense of the measurement response time.
The ideal digital filter setting is application specific and is normally a balance between CO2 reading
accuracy and response time. The SprintIR®‐W sensor will also output the raw unfiltered CO2
measurement data. This data can be post processed using alternative filter algorithms.
Filter Effect on Measurement Data Outputs
900
800
CO2 Levels (ppm)
700
600
500
400
Filtered (Z)
300
Unfiltered (z)
200
100
0
1
11
21
31
41
51
# Measurements
The graph above shows the effects of the filter on the CO2 measurement data (Z or z). The unfiltered
output is shown in orange and the filtered output shown in blue.
Filter Response vs. Filter Setting
4500
4000
CO2 Level (ppm)
3500
A=16
3000
A=32
2500
A=64
A=128
2000
T90
1500
1000
500
0
0
50
100
150
200
250
300
350
400
# Measurements
The graph above shows the effect of the filter on response times. Increasing the filter setting
increases the measurement output response time. T90 is the time to 90% of reading. The SprintIR®‐
W takes 20 readings per second. The flow rate was set at 0.2l/min.
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SprintIR®‐W
High Speed CO2 Sensor
Sampling noise is progressively reduced with higher digital filter settings. It is recommended the
user sets the highest value digital filter setting without compromising the required flow rate.
Flow Rate
Recommended Digital Filter Setting ‘a’
0.1litre/minute
64
0.5litre/minute
32
1litre/minute
16
5litre/minute
8
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ZERO POINT SETTING
SprintIR®‐W
High Speed CO2 Sensor
There are a several methods available to the user to set the zero point of the sensor. The
recommended method is zero‐point setting in a known gas concentration. In all cases, the best zero
is obtained when the gas concentration is stable, and the sensor is at a stabilised temperature.
Note that 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.
To improve zeroing accuracy, the recommended digital filter setting is 32. See the ‘A’ command.
ZERO IN A KNOWN GAS CONCENTRATION
Place the sensor in a known gas concentration, power up the sensor and allow time for the sensor
temperature to stabilise, and for the gas to be fully diffused into the sensor.
Send the ZERO IN A KNOWN GAS CONCENTRATION command X to the sensor. The sensor will be
zeroed using the known gas concentration level sent by the user. The concentration value written to
the sensor must be scaled dependent on the sensor CO2 measurement range. The multiplier for the
scaling factor is set according to the range of the sensor, see the ‘.’ command.
ZERO IN NITROGEN
Place the sensor in nitrogen gas and allow time for the sensor temperature to stabilise and the gas
to be fully diffused into the sensor. Send the ZERO IN NITROGEN command U to the sensor. The
sensor is calibrated assuming a 0ppm CO2 environment.
ZERO IN FRESH AIR
If there is no calibration gas or nitrogen available, the sensor zero point can be set in fresh air.
Ambient CO2 concentrations in fresh air are typically 400ppm. The CO2 concentration fresh air zero
level is programmable over a range from 0ppm to the full scale of the sensor.
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 diffused into the sensor. Power up the sensor, write the G command
to the sensor. The concentration value written to the sensor must be scaled dependent on the
sensor CO2 measurement range. The sensor can use the default fresh air CO2 concentration value
(400ppm), or the user can write a different fresh air value to the sensor if desired.
ZERO POINT ADJUSTMENT
If the CO2 concentration and the sensor reported concentration are known, the zero point can be
adjusted using the known concentration to fine tune the zero point. For example, if the sensor has
been in an environment that has been exposed to outside air, and the sensor reading is known at
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SprintIR®‐W
High Speed CO2 Sensor
that time, the zero point can be fine‐tuned to correct the reading. This is typically used to
implement automated zeroing routines.
The known CO2 concentration value and the reported CO2 value from the sensor can be sent to the
sensor using the ZERO POINT ADJUSTMENT command F.
AUTO‐ZERO FUNCTION
The sensor has a built‐in auto‐zeroing function. In order to function correctly, the sensor must be
exposed to typical background levels (400‐450ppm) at least once during the auto‐zeroing period.
For example, many buildings will drop quickly to background CO2 levels when unoccupied overnight
or at weekends. The auto‐zeroing function uses the information gathered during these periods to
re‐zero. The sensor will reset the ‘zero’ level every time it does an auto‐zero. Auto‐zeroing is
enabled by default. If the sensor is powered down, the auto‐zero is reset to default values.
The auto‐zero function works in the same way as the ZERO IN FRESH AIR command. Auto‐zeroing is
disabled by default, but can be enabled to operate automatically, or zeroing can be forced. The user
can also independently adjust the CO2 level used for auto‐zeroing. Typically, it is set to the same
value as the ZERO IN FRESH AIR value, but it can also be set at a different level if desired.
AUTO‐ZERO INTERVALS
The auto‐zeroing period can be programmed by the user. The sensor can be programmed to
undertake an initial auto‐zero after power‐on. Thereafter, the auto‐zero period can be set
independently of the start‐up zeroing time. Note, the zeroing settings are reset if the sensor is
powered down.
AUTO‐ZERO SETTINGS
By default, the sensor will automatically ‘zero’ using the measured CO2 level sampled during the
auto‐zeroing period. The user can alter the behaviour of the sensor as a result of the auto‐zero
process.
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SprintIR®‐W
High Speed CO2 Sensor
PRESSURE AND CONCENTRATION LEVEL COMPENSATION
NDIR gas sensors detect the concentration of gas by measuring the degree of light absorption by the
gas analyte. The degree of light absorption is converted into a concentration reported by the sensor.
The absorption process is pressure and gas concentration dependent. In general, as the pressure
increases, the reported gas concentration also increases. As the pressure decreases, the reported
concentration decreases. This effect takes place at a molecular level and is common to all NDIR gas
sensors.
GSS sensors are calibrated at 1013mbar and 450ppm CO2. The reading will vary due to pressure and
CO2 concentration. It is possible to correct for the effects of pressure and concentration by setting a
compensation value. This will apply a permanent correction to the output of the sensor, depending
on the compensation value. The compensation value needs to be written to the sensor and will
overwrite the default 1013mbar and 450ppm CO2 value. The new compensation value will be used
for all subsequent measurements and will be retained after a power cycle.
ALTITUDE COMPENSATION TABLE
Altitude
(ft.)
Altitude
(m)
Pressure
(mbar)
Sea Level
Difference
%
Change
per
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
6,000
7,000
8,000
9,000
10,000
0
153
305
458
610
763
915
1,068
1,220
1,373
1,525
1,830
2,135
2,440
2,745
3,050
1,013
995
977
960
942
925
908
891
875
859
843
812
782
753
724
697
0
18
36
53
71
88
105
122
138
154
170
201
231
260
289
316
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.14
CO2
Measurement
Change (%)
0
3
5
7
10
12
15
17
19
22
24
28
32
36
40
44
Compensation
Value
8,192
8,398
8,605
8,800
9,006
9,201
9,396
9,591
9,775
9,958
10,142
10,497
10,841
11,174
11,506
11,816
Other compensation values can be calculated using the following formula.
𝑪𝒐𝒎𝒑𝒆𝒏𝒔𝒂𝒕𝒊𝒐𝒏 𝑽𝒂𝒍𝒖𝒆
𝟖𝟏𝟗𝟐
𝑺𝒆𝒂 𝑳𝒆𝒗𝒆𝒍 𝑫𝒊𝒇𝒇𝒆𝒓𝒆𝒏𝒄𝒆 ∗ 𝟎. 𝟏𝟒
∗ 𝟖𝟏𝟗𝟐
𝟏𝟎𝟎
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SprintIR®‐W
High Speed CO2 Sensor
The pressure compensation values calculated above are only approximate and only valid for
concentrations below 1%. For higher accuracy compensation, the sensor output must be adjusted
for both pressure and concentration as the CO2 level measured by the sensor is affected by both
ambient pressure and gas concentration levels. To calculate the adjusted CO2 level, use the
following calculator.
The corrected CO2 level (C2) = C1/(1+Y(1013‐P)),
where,
C1 = Concentration reading from sensor
P = Pressure in mbar
Where concentration 1500ppm.
Y = 2.37472E‐30 C16 ‐ 2.70695E‐25 C15 + 1.24012E‐20 C14 ‐ 2.91716E‐16 C13 + 3.62939E‐12 C12 ‐
1.82753E‐08 C1 ‐ 1.35129E‐03
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SprintIR®‐W
High Speed CO2 Sensor
CONTROL INTERFACE
The SprintIR® family of sensors are controlled by writing and reading from the sensor via its UART
interface. The Rx_In and Tx_Out pins are normally high, suitable for direct connection to a UART. If
the sensor is to be read by a true RS232 device (e.g. a PC), it is necessary to pass through a level
converter to step up/down the voltage and invert the signal.
CONTROL INTERFACE TIMING ‐ UART MODE
PARAMETER
Baud Rate
Data Bits
Parity
Stop Bits
Hardware Flow Control
SYMBOL
MIN
TYP
9600
8
None
1
None
MAX
UNIT
Bits/s
UART COMMAND PROTOCOL
All UART commands must be terminated with a carriage return and line feed , hex 0x0D
0x0A. In this document, this is shown as ‘\r\n’. UART commands that take a parameter always have
a space between the letter and the parameter. The sensor will respond with a ‘?’ if a command is
not recognised. The two most common causes are missing spaces or missing terminators.
All command communications are in ASCII and are terminated by carriage return, line feed (0x0D
0x0A). This document uses the protocol “\r\n” to indicate the carriage return line feed. All
responses from the sensor, including measurements, have a leading space (ASCII character 32).
The character ‘#’ represents an ASCII representation of a numeric character (0‐9). Note there is a
space between the first letter and any parameter. For example, the X command reads “X space 2000
carriage return line feed”.
UART OPERATION
When initially powered, the sensor will immediately start to transmit a CO2 reading on receiving any
character.
The CO2 measurement is reported as:
Z #####\r\n
where Z ##### shows the CO2 concentration.
Note that all outputs from the sensor have a leading space.
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UART INTERFACE SUMMARY
SprintIR®‐W
High Speed CO2 Sensor
Syntax
Use
Example
Response
Comments
A ###\r\n
Set value of the
digital filter
Return the value of
the digital filter
Fine Tune the zero
point
Zero‐point setting
using fresh air
Returns the relative
humidity value
Switches the sensor
between different
modes
Sets the number of
measurement data
types output by the
sensor
Sets value of CO2
background
concentration in ppm
for auto‐zeroing
A 128\r\n
A 00128\r\n
See “Digital Filter”
a\r\n
a 00128\r\n
See “Digital Filter”
F 410 400\r\n
F 33000\r\n
G\r\n
G 33000\r\n
H 00551\r\n
See “Zero Point
Setting”
See “Zero Point
Setting”
K 1\r\n
K 1\r\n
M 6\r\n
M 6\r\n
See “Output Fields”
P 8 1\r\n
P 9 144\r\n
P 10 ###\r\n
P 11 #\r\n
Sets value of CO2
background
concentration in ppm
used for zero‐point
setting in fresh air.
P 10 1\r\n
P 11 144\r\n
Q\r\n
Reports the latest
measurement data
types, as defined by
‘M’
Sets the pressure and
concentration
compensation value
Returns the pressure
and concentration
compensation value
Returns the
temperature value
Zero‐point setting
using nitrogen
Manual setting of the
zero point.
Zero‐point setting
using a known gas
calibration
Return firmware
version and sensor
serial number
Q\r\n
H 12345 T 12345 Z
00010\r\n
Two‐byte value,
P 8 = MSB
P 9 = LSB
400ppm in the
example
Two‐byte value,
P 8 = MSB
P 9 = LSB
400ppm in the
example
S 8192\r\n
S 08192\r\n
s\r\n
s 08192\r\n
T 01224\r\n
U\r\n
U 33000\r\n
u 32997\r\n
u 32997\r\n
X 2000\r\n
X 32997\r\n
Y\r\n
Returns two lines
a\r\n
F ##### #####\r\n
G\r\n
H\r\n
K #\r\n
M ###\r\n
P 8 ###\r\n
P 9 #\r\n
S #####\r\n
s\r\n
T\r\n
U\r\n
u #####\r\n
X #####\r\n
Y\r\n
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See “Pressure and
Concentration
Compensation”
See “Pressure and
Concentration
Compensation”
See “Zero Point
Setting”
See “Zero Point
Setting”
See “Zero Point
Setting”
Production Data, Revision 4.2, June 2020
Copyright © 2020 Gas Sensing Solutions Ltd.
SprintIR®‐W
High Speed CO2 Sensor
Syntax
Use
Example
Response
Comments
Z\r\n
Return the most
recent filtered CO2
measurement in ppm
Return the most
recent unfiltered CO2
measurement in ppm
Sets the timing for
initial and interval
auto‐zeroing periods
Returns the auto‐
zeroing configuration
Switch auto‐zeroing
on or off
Returns the scaling
factor multiplier
required to convert
the Z or z output to
ppm
Z\r\n
Z 01521\r\n
z\r\n
Z 01521\r\n
@ 1.0 8.0\r\n
@ 1.0 8.0\r\n
See “Auto‐zeroing” for
details
@ 1.0 8.0\r\n
@ 1.0 8.0\r\n
@ 0\r\n
@ 0\r\n
.\r\n
. 00010\r\n
See “Auto‐zeroing” for
details
See “Auto‐zeroing” for
details
Multiply by 10 in the
example
z\r\n
@ #.# #.#\r\n
@ r\n
@ #r\n
.\r\n
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SprintIR®‐W
High Speed CO2 Sensor
CO2 LEVEL MEASUREMENT VALUE ‐ Z INFORMATION (0x5A)
Description
Syntax
Example
Response
Reports the latest filtered CO2 measurement
ASCII Character 'Z', terminated by 0x0D 0x0A (CR & LF)
Z\r\n
Z 00521\r\n
This value needs to be multiplied by the appropriate scaling factor to derive the ppm value. See the
‘.’ command.
CO2 LEVEL MEASUREMENT VALUE ‐ z INFORMATION (0x7A)
The sensor is also capable of reporting the real time unfiltered CO2 measurement value.
Description
Syntax
Example
Response
Reports the unfiltered CO2 measurement
ASCII Character 'Z', terminated by 0x0D 0x0A (CR & LF)
z\r\n
z 00521\r\n
‘.’ COMMAND (0x2E)
To calculate the measurement value in ppm, the ‘Z’ or ‘z’ value, they must be converted into ppm by
using the ‘.’ multiplier factor. This multiplier will depend on the full‐scale measurement range of the
sensor. The multiplier is related to the full‐scale range of the sensor.
The multiplier must also be used when sending CO2 concentration levels to the sensor, for example
when setting the fresh air CO2 concentration value. The ‘.’ Command can also be used to read back
the scaling factor.
For example, if the user wants to zero the sensor in a known concentration of gas (e.g. 450ppm), the
value written to the sensor must be 450/scaling factor.
Description
Syntax
Example
Response
Returns a number indicating what multiplier must be applied to the Z CO2
measurement output to convert it into ppm.
ASCII character '.', terminated by 0x0D 0x0A ( CR & LF )
.\r\n
. 00010\r\n
(this number is variable, usually 10)
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SprintIR®‐W
High Speed CO2 Sensor
Measurement
Range of Sensor
CO2 Measurement CO2 Measurement
Scaling Factor (Z) Output Units
Example
0 – 60%
10
ppm/10
Z 01200 = 12000ppm = 1.2%
0 – 100%
100
ppm/100
Z 01500
= 15000ppm = 15%
TEMPERATURE MEASUREMENT VALUE ‐ SprintIR®‐W Option
Command
Use
Example
Response Comments
T\r\n
Returns the most
recent temperature
measurement.
T #####\r\n
T 01224\r\n
Where ##### is a 5‐digit number.
Temperature (°C) = (##### ‐ 1000)/10.
22.4°C in the example
Description
Syntax
Example
Response
Returns the most recent temperature measurement.
ASCII character 'T', SPACE, decimal, terminated by 0x0D 0x0A ( CR & LF )
T\r\n
T 01224\r\n (this number is variable)
HUMIDITY MEASUREMENT VALUE ‐ SprintIR®‐W Option
Command
Use
Example
Response
Comments
H\r\n
Return the most
recent humidity
measurement.
H #####\r\n
H 00551\r\n
Where ##### is a 5‐digit
number.
Humidity (%RH) = #####/10.
55.1% RH in the example
Description
Syntax
Example
Response
Returns the most recent the humidity measurement.
ASCII character 'H', SPACE, decimal, terminated by 0x0D 0x0A ( CR & LF )
H\r\n
H 00551\r\n (this number is variable)
Note both temperature and humidity outputs are a factory fit option on the SprintIR®‐W only. If not
fitted, sensor will return either T 00000 or H 00000.
The sensor default data output is filtered CO2 only. To output temperature, humidity, and filtered
CO2, send “M 4164\r\n” (see “Output Fields”).
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SprintIR®‐W
High Speed CO2 Sensor
The output format will have the form: H 00345 T 01195 Z 00065\r\n
This example indicates 34.5% RH, 19.5°C and 650ppm CO2.
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SprintIR®‐W
High Speed CO2 Sensor
K COMMAND
Command
Use
Default
Range
Example
Response
Comments
K #\r\n
Switches the
sensor between
different control
modes
1
K 1\r\n
K 1\r\n
See ‘K’ Commands
K COMMAND (0x4B)
Description
Syntax
Sets the control interface mode
ASCII character 'K', SPACE, mode number, terminated by 0x0D 0x0A (CR &
LF)
K 1\r\n
K 00001\r\n
(this number is variable)
Example
Response
DIGITAL FILTER COMMANDS
Command
Use
Default
Range
Example
Response
Comments
A ###\r\n
Set value of the
digital filter
16
0 ‐
65635
A 16\r\n
A 00016\r\n
a\r\n
Return value of
digital filter
0 ‐
65365
a\r\n
a 00016\r\n
A COMMAND (0x41)
Description
Syntax
Example
Response
Set the value for the digital filter
ASCII character 'A', SPACE, decimal, terminated by 0x0D 0x0A (CR & LF)
A 16\r\n
A 00016\r\n (this number is variable)
a COMMAND (0x61)
Description
Syntax
Example
Response
Set the value for the digital filter
ASCII character 'A', SPACE, decimal, terminated by 0x0D 0x0A (CR & LF)
A 16\r\n
A 00016\r\n (this number is variable)
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SprintIR®‐W
High Speed CO2 Sensor
ZERO POINT SETTING COMMANDS
Command
Use
Default
Range
Example Response
Comments
F #####
#####\r\n
Fine Tune the
zero point
Range of
sensor
F 410
400\r\n
F 33000\r\n
See “Zero Point
Setting”
G\r\n
Zero‐point
setting using
fresh air
G\r\n
G 33000\r\n
See “Zero Point
Setting”
U\r\n
Zero‐point
setting using
nitrogen
U\r\n
U 33000\r\n
See “Zero Point
Setting”
u #####\r\n
Manual setting
of the zero
point
u
32997\r\n
u 32997\r\n
See “Zero Point
Setting”
X #####\r\n
Zero‐point
setting using a
known gas
concentration
Range of
sensor
X 2000\r\n
X 32997\r\n
See “Zero Point
Setting”
P 8 ###\r\n
P 9 #\r\n
Sets value of
CO2
background
concentration
in ppm for
auto‐zeroing
P 8 1\r\n
P 9 144\r\n
Two‐byte value,
P 8 = MSB
P 9 = LSB
400ppm in the
example
P 10 ###\r\n
P 11 #\r\n
Sets value of
CO2
background
concentration
in ppm used
for zero‐ point
zeroing in
fresh air.
P 10 1\r\n
P 11 144\r\n
Two‐byte value,
P 8 = MSB
P 9 = LSB
400ppm in the
example
F COMMAND (0x46)
Description
Syntax
Example
Response
Calibrates the zero‐point using a known reading and a known CO2
concentration terminated by 0x0D 0x0A (CR & LF)
ASCII character 'F', SPACE, then the reported gas concentration, SPACE, then
the actual gas concentration, terminated by 0x0D 0x0A (CR & LF)
F 41 39\r\n
F 33000\r\n (the numbers are variable)
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SprintIR®‐W
High Speed CO2 Sensor
G COMMAND (0x47)
Description
Syntax
Example
Response
Sets the zero point assuming the sensor is in fresh air (typically 400ppm CO2,
but level can be set by user – see P commands.)
ASCII character 'G' terminated by 0x0D 0x0A (CR & LF)
G\r\n
G 33000\r\n (the number is variable)
U COMMAND (0x55)
Description
Syntax
Example
Response
Sets the zero point assuming the sensor is in 0ppm CO2 such as nitrogen.
ASCII Character 'U' terminated by 0x0D 0x0A (CR & LF)
U\r\n
U 32767\r\n (the number is variable)
u COMMAND (0x75)
Description
Syntax
Example
Response
Forces a specific zero set point value.
Input value is scaled by CO2 value multiplier, see ‘.’ command.
ASCII character 'u', SPACE, then the gas concentration, terminated by 0x0D
0x0A (CR & LF)
u 32767\r\n
u 32767\r\n
X COMMAND (0x58)
Description
Syntax
Example
Response
Sets the zero point with the sensor in a known concentration of CO2. Input
value is scaled by CO2 value multiplier, see ‘.’ command.
ASCII character 'X', SPACE, then the gas concentration, terminated by 0x0D
(CR & LF)
X 1000\r\n
X 33000\r\n (the number is variable).
P COMMAND ‐ CO2 Level for Auto‐Zeroing
Description
Syntax
Example
Response
Sets the value of CO2 in ppm used for auto‐zeroing.
Input value is scaled by CO2 value multiplier, see ‘.’ command.
ASCII character 'P', SPACE, then 8, SPACE, then MSB terminated by 0x0D
0x0A (CR & LF)
ASCII character 'P' then a space, then 9, then a space, then LSB terminated
by 0x0D 0x0A (CR & LF)
P 8 0\r\n
P 9 40\r\n
p 8 0\r\n
p 9 40\r\n
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SprintIR®‐W
High Speed CO2 Sensor
The value is entered as a two‐byte word, MSB first.
MSB = Integer (Concentration/256)
LSB = Concentration – (256*MSB)
In the above example, target CO2 background concentration is 400ppm.
MSB = Integer (400/256) = 1
LSB = 400 – 256 = 144
P COMMAND – CO2 Level for Zero‐Point Setting
Description
Syntax
Example
Response
Sets value of CO2 in ppm for zero‐point setting in fresh air.
Input value is scaled by CO2 value multiplier, see ‘.’ command.
ASCII character 'P', SPACE, then 10, SPACE, then MSB terminated by 0x0D
0x0A (CR & LF)
ASCII character 'P', SPACE, then 11, SPACE, then LSB terminated by 0x0D
0x0A (CR & LF)
P 10 7\r\n
P 11 208\r\n
p 10 7\r\n
p 11 208\r\n
MSB = Integer (Concentration/256)
LSB = Concentration – (256*MSB)
In the above example, target zero‐point CO2 concentration is 2000ppm.
MSB = Integer (2000/256) = 7
LSB = 2000 – (256*MSB) = 208
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SprintIR®‐W
High Speed CO2 Sensor
AUTO‐ZEROING INTERVALS
UART
Command
Use
Default Range Example
Response
Comments
@ #.# #.#\r\n
Auto‐zeroing
interval
settings
@ 1.0 8.0\r\n
See “Auto‐
Zeroing” for
details
@ 1.0 8.0\r\n
@ COMMAND (0x2E)
Description
Syntax
Example
Response
Set the ‘Initial Interval’ and ‘Regular Interval’ for auto‐zeroing events.
ASCII character '@', SPACE, decimal, SPACE, decimal terminated by 0x0D
0x0A (CR & LF)
@ 1.0 8.0\r\n
@ 1.0 8.0\r\n (the number mirrors the input value)
Both the initial interval and regular interval are given in days. Both must be entered with a decimal
point and one figure after the decimal point. In the above example, the auto‐zeroing interval is set to
8 days, and the initial interval set to 1 day.
To disable auto‐zeroing, send @ 0\r\n.
To start an auto‐zeroing immediately, send 65222\r\n.
To determine the auto‐zero configuration, send @\r\n.
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SprintIR®‐W
High Speed CO2 Sensor
PRESSURE AND CONCENTRATION COMPENSATION
UART
Command
Use
Default Range
Example
Response
Comments
S #####\r\n
Sets the pressure
and concentration
compensation value
8192
0‐65536
S 8192\r\n
S 08192\r\n
See “Pressure and
Concentration
Compensation”
s\r\n
Returns the
pressure and
concentration
compensation value
s\r\n
s 08192\r\n
See “Pressure and
Concentration
Compensation”
S COMMAND (0x53)
Description
Syntax
Example
Response
Set the ‘Pressure and Concentration Compensation' value
ASCII character 'S', SPACE, decimal, terminated by 0x0D 0x0A (CR & LF)
S 8192\r\n
S 8192\r\n
(the number mirrors the input value)
s COMMAND (0x73)
Description
Syntax
Example
Response
Reports the ‘Pressure and Concentration Compensation' value.
ASCII Character 's', terminated by 0x0D 0x0A (CR & LF)
s\r\n
s 8192\r\n
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SprintIR®‐W
High Speed CO2 Sensor
MEASUREMENT DATA OUTPUTS
The SprintIR®‐W sensor can provide multiple measurement types as a single string of data.
UART
Command
Use
Default
Range
Example
Response
M #####\r\n
Sets the number of
measurement data
types output by
the sensor. #####
is the mask value
M 04164\r\n
See “Output M #####\r\n
Fields”
Comments
Sets the number of
measurement data
types output by
the sensor
Measurement Parameter
Humidity
Temperature
CO2 (Filtered)
CO2 (Unfiltered)
Field Identifier
H
T
Z
z
Mask Value
4096
64
4
2
The required mask value is the sum of the ‘Mask Value’ for each field required. To output filtered
and unfiltered CO2 data, set M=6.
M COMMAND
Description
Syntax
Example
Response
Sets the type and number of data outputs
ASCII character 'M', terminated by 0x0D 0x0A ( CR & LF )
M\r\n
M 04164\r\n
Q COMMAND
Description
Syntax
Example
Response
Reports the number of output data fields
ASCII character 'Q', SPACE, then Mask Value, terminated by 0x0D 0x0A ( CR
& LF )
Q\r\n
Z 00010\r\n
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SprintIR®‐W
High Speed CO2 Sensor
SERIAL NUMBER AND FIRMWARE VERSION
UART
Command
Use
Default Range Example
Response
Comments
Y\r\n
Return
firmware
version and
sensor serial
number
Returns two
lines
Y\r\n
Y COMMAND (0x59)
Description
Syntax
Example
Response
The present version string for the firmware and serial number of the sensor.
ASCII character 'Y', terminated by 0x0D 0x0A ( CR & LF )
Y\r\n
Y,Jan 30 2013,10:45:03,AL17\r\n
ingB 00233 00000\r\n
N.B. This command returns two lines split by a carriage return line feed and terminated by a carriage
return line feed. This command requires that the sensor has been stopped (see ‘K’ command).
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SprintIR®‐W
High Speed CO2 Sensor
CONNECTION DIAGRAM FOR UART INTERFACE
SENSOR SLAVE
UART MASTER
Rx_IN
Tx_OUT
Tx_OUT
Rx_IN
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SprintIR®‐W
High Speed CO2 Sensor
IMPORTANT NOTICE
Gas Sensing Solutions Ltd. (GSS) products and services are sold subject to GSS’s terms and conditions of sale,
delivery and payment supplied at the time of order acknowledgement. GSS warrants performance of its
products to the specifications in effect at the date of shipment. GSS reserves the right to make changes to its
products and specifications or to discontinue any product or service without notice.
Customers should therefore obtain the latest version of relevant information from GSS to verify that the
information is current. Testing and other quality control techniques are utilised to the extent GSS deems
necessary to support its warranty. Specific testing of all parameters of each device is not necessarily
performed unless required by law or regulation. In order to minimise risks associated with customer
applications, the customer must use adequate design and operating safeguards to minimise inherent or
procedural hazards. GSS is not liable for applications assistance or customer product design. The customer is
solely responsible for its selection and use of GSS products. GSS is not liable for such selection or use nor for
use of any circuitry other than circuitry entirely embodied in a GSS product.
GSS products are not intended 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
intellectual property right of GSS covering or relating to any combination, machine, or process in which its
products or services might be or are used. Any provision or publication of any third party’s products or
services does not constitute GSS’s approval, licence, warranty or endorsement thereof. Any third‐party
trademarks contained in this document belong to the respective third‐party owner.
Reproduction of information from GSS datasheets is permissible only if reproduction is without alteration and
is accompanied by all associated copyright, proprietary and other notices (including this notice) and
conditions. GSS is not liable for any unauthorised alteration of such information or for any reliance placed
thereon.
Any representations made, warranties given, and/or liabilities accepted by any person which differ from those
contained in this datasheet or in GSS’s standard terms and conditions of sale, delivery and payment are made,
given and/or accepted at that person’s own risk. GSS is not liable for any such representations, warranties or
liabilities or for any reliance placed thereon by any person.
ADDRESS
Gas Sensing Solutions Ltd.
Grayshill Road
Cumbernauld
G68 9HQ
United Kingdom
Gas Sensing Solutions Ltd.
Page | 36 For regular updates, go to https://www.gassening.co.uk
Production Data, Revision 4.2, June 2020
Copyright © 2020 Gas Sensing Solutions Ltd.
REVISION HISTORY
DATE
16/04/2020
28/04/2020
11/06/2020
RELEASE
4.0
4.1
4.2
SprintIR®‐W
High Speed CO2 Sensor
DESCRIPTION OF CHANGES
First revision
Changed zero settings language
Absolute Maximum Ratings, Mechanical
Sealing
PAGES
All
All
P. 8
Gas Sensing Solutions Ltd.
Page | 37 For regular updates, go to https://www.gassening.co.uk
Production Data, Revision 4.2, June 2020
Copyright © 2020 Gas Sensing Solutions Ltd.
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