MFrontier NDIR CO2 Sensor Module Instruction Manual

MFrontier NDIR CO2 Sensor Module

MTP80-A is a dual channel carbon dioxide sensor based on the principle of Non Spectral Infrared (NDIR) technology. It can detect the concentration of carbon dioxide in the air in real time and output the concentration value through UART, IIC, and PWM methods. It has strong anti-interference ability, high sensitivity, strong stability, long lifespan, low power consumption, and supports two calibration methods: self calibration and manual calibration, with minimal data accuracy error. Suitable for industries such as air monitoring, fresh air systems, smart homes, and in car air purification.

Advantage

• Long term stability advantage – The stability of NDIR sensors mainly depends on the light source, and under the condition of no abnormalities in the light source, the long-term stability of NDIR is extremely excellent compared to other types of gas sensors .
• The working principle of an NDIR sensor for measuring concentration is to detect the infrared energy of the characteristic infrared absorption band of the measured gas. The signal characteristic is that when there is no measured gas, the signal strength is maximum, and the higher the concentration, the smaller the signal. The measured concentration can reach 10000PPM.

Features

• NDIR detection principle
• Short preheating time
• Temperature compensation and automatic calibration algorithms
• High sensitivity and precision
• Anti interference and strong stability

Applications

• Air quality monitoring equipment
• Fresh air system
• Car air purification
• Air purification equipment
• HAVC system
• Smart Home

Size

Parameters

Pin diagram

Pin Definition

Pin number| Pin name| Pin Function Description| Pin electrical characteristics
---|---|---|---
1| VIN| Positive end of power supply| Equipped with anti reverse connection protection and input voltage range：4.2V-5.5V
2| GND| Power supply negative terminal|

3

|

Alarm- OC

| Alarm function, pin in open drain output mode. When the measured concentration is greater than 1000ppm, the output of this pin is high.

When the concentration is less than 800ppm, the output of this pin is low

|

The pin is in open drain output mode, and an external pull-up resistor is required for use.

4

|

PWM

|

PWM function, used to output CO2 concentration.

| The pin is in push-pull output mode, and the output PWM cycle is 1004ms.

5

|

VCC-Out

| The internal LDO output of the sensor is usually 3V ± 2%. Generally used for serial communication level conversion.| Output voltage: 3.3V ± 2%, maximum without overcurrent protection Output current: 6mA

6

|

Host-TX

/IIC-SDA

|

The TX pin of the UART in the main system is usually the TX of the customer MCU or the SDA of the IIC function.

| The usual communication level is 3.3V. When used for IIC function, the pin configuration is open drain mode, and an external pull-up resistor is required for use.

7

|

Host-RX

/IIC-SCL

|

The RX pin of the UART in the main system is usually the RX of the customer MCU or the SCL of the IIC function.

| The usual communication level is 3.3V. When used for IIC function, the pin configuration is open drain mode, and an external pull-up resistor is required for use.

8

|

R/T

|

This pin has two functions:

1.  As an RS485 directional control pin. This pin is in open drain output mode and can be directly connected to the direction enable pin of the RS485 chip, requiring an external pull-up resistor. At this time, modules Pin6 and Pin7 are UART functions.

2.  UART/IIC function selection pin. This pin is grounded before power on (grounding after power on is invalid), and Pin6 and Pin7 of the module are IIC functions. When the pin is powered on, it is in pull-up input mode and can be suspended or grounded

. As an RS485 direction enable pin, it is in open drain output mode and requires an external pull-up resistor.

| When the pin is po w ered on, it is in pull- up input mode and can be suspended or grounded. As an RS485 direction enable pin, it is in open drain output mode and requires an external pull-up resistor.
9| bCAL-in| Manual calibration of control pins| When the pin is powered on, it is in input mode with pull-up resistance

Calibration function

The MTP80 module is a precision optical module. After leaving the factory, due to various reasons such as transportation, installation, welding, etc., the measurement of the module may experience certain drift, resulting in a decrease in accuracy. The module is equipped with a set of self calibration algorithms that can periodically and automatically correct measurement errors, ensuring that the module maintains good measurement accuracy. The default self calibration cycle of the module is 7 days (168 hours), which can be adjusted by command (24 hours to 720 hours).

To ensure the measurement accuracy of the calibrated sensor, please ensure that the concentration of CO2 in its working environment can approach outdoor atmospheric levels for at least a few hours within 7 days of power on.

Alarm function

The MTP80 module supports alarm output function and outputs through the Alarm OC pin. When the measured CO2 concentration value is greater than 1000ppm, the Alarm OC pin outputs a high level. When the measured CO2 concentration value is less than 800PPM, the Alarm OC pin outputs a low level. Note that the Alarm OC pin is configured in open drain output mode and requires an external pull- up resistor to be used. If an error occurs in the module, the Alarm OC pin will remain high.
The reference usage method is shown in the figure on the right.

Communication protocol

serial communication
The baud rate for serial communication is 9600bps, and the serial communication packet is defined as follows:

Protocol format
Frame format description:

the data

The following protocol description applies to the gas sensor series, with instruction byte 0xA0.
Command Byte Description

1013.0hPa)
0x0002| Read the current set air pressure value
0x0003| Reading gas concentration values
0x0004| Single point correction function (with reference concentration)
0x0005| Single point correction reading status
0x0006| Prohibit or enable self calibration
0x0007| Read self calibration status
0x0008| Read self calibration cycle (hours)
0x0009| Set self calibration cycle (hours)

Basic Control Protocol

Function Name| Frame header| Instruction byte| Command Bytes| Data length| Data| Checksum
---|---|---|---|---|---|---
Setting air pressure parameters|

MCU sends

| 0x42 0x4d| 0xA0| 0x0001| 0x00 0x02| The atmospheric pressure value range is 700–1100 (16-bit integer)|

Checksum

Module return

| s 0x42 0x4d| 0xA0| 0x0001| 0x00 0x00|  | Checksum
Read the current air pressure value|

MCU sends

| 0x42 0x4d| 0xA0| 0x0002| 0x00 0x00|  |

Checksum

Module return

| s 0x42 0x4d| 0xA0| 0x0002| 0x00 0x02| Atmospheric pressure value (16-bit integer)|

Checksum

Read the current concentration value

|

MCU sends

| 0x42 0x4d| 0xA0| 0x0003| 0x00 0x00|  | Checksum

Module return

|

s

0x42 0x4d

|

0xA0

|

0x0003

|

0x00 0x05

| Gas concentration value (32-bit integer) and data validity flag (8-bit) 0x00: valid; 0xFF: data unavailable;|

Checksum

Single point correction function ( with reference concentration)|

MCU sends

| 0x42 0x4d| 0xA0| 0x0004| 0x00 0x04| The reference concentration range is 400~5000 (32-bit integer)| Checksum

Module return

|

s

0x42 0x4d

|

0xA0

|

0x0004

|

0x00 0x01

|

0x01: indicates calibration start; 0xf: indicates calibration error

|

Checksum

Read single point correction status|

MCU sends

| 0x42 0x4d| 0xA0| 0x0005| 0x00 0x00|  | Checksum

Module return

| s 0x42 0x4d| 0xA0| 0x0005| 0x00 0x01| 0x00: indicates calibration completed; 0x01: indicates calibration still in progress|

Checksum

Enable or disable self- calibration|

MCU sends

| 0x42 0x4d| 0xA0| 0x0006| 0x00 0x01|

0x00: enables self-calibration; 0xf: disables self-calibration

|

Checksum

Module return

| s 0x42 0x4d| 0xA0| 0x0006| 0x00 0x00|  |

Checksum

Read self- calibration status|

MCU sends

| 0x42 0x4d| 0xA0| 0x0007| 0x00 0x00|  |

Checksum

Module return

| s 0x42 0x4d| 0xA0| 0x0007| 0x00 0x01| 0x00: Enable self-calibration 0xf: Disable self- calibration|

Checksum

Read Self- calibration cycle|

MCU sends

| 0x42 0x4d| 0xA0| 0x0008| 0x00 0x00|  |

Checksum

Module return

| s 0x42 0x4d| 0xA0| 0x0008| 0x00 0x02|

Self-calibration cycle range: 24–720h

|

Checksum

Setting the self- calibration period

|

MCU sends

| 0x42 0x4d| 0xA0| 0x0009| 0x00 0x02| Self-calibration cycle range: 24–720h|

Checksum

Module return

|

s

0x42 0x4d

|

0xA0

|

0x0009

|

0x00 0x01

| 00: Correct operation; 01: The input data is less than 24 hours and will not     be     accepted; 02: The input data is greater than 720 hours and will not be accepted|

Checksum

Application Examples

IIC instruction analysis

The module works in IIC slave mode and can be connected to an external MCU. The module contains a pull-up resistor.
The module device slave address is: 0x32 (7-bit address)
The module write operation address is: 0x64
The module read operation address is: 0x65

Host sending sequence:

1. Send start signal
2. Send address write (slave address + R/W = 0x64) and check response
3. Send read command (0x03) and check response
4. Send stop signal
5. Send start signal
6. Send address read (slave address + R/W (1) = 0x65) and check response
7. Read 3 bytes from the module and send response
8. Send stop signal

The received 3 bytes data are described as follows:

Note:
CO2 concentration = high byte of CO2 concentration * 256 + low concentration byte
Data valid byte, 0x00 means valid data, 0xf means invalid data

PWM function detailed explanation

• The PWM cycle is 1004ms
• The high level output is 2ms in the starting stage
• The middle cycle is 1000ms
• The low level output is 2ms in the ending stage
• The calculation formula for obtaining the current CO2 concentration value through PWM is:
• Cppm = 5000*(TH-2ms)/(TH+TL-4ms)
• Cppm is the calculated CO2 concentration value, in ppm
• TH is the time when the output is high level in an output cycle
• TL is the time when the output is low level in an output cycle

Reliability Test

Test items| Experimental conditions| Acceptance conditions| Number of verifications n Number of failures c
---|---|---|---
High temperature storage| 60±2, store without power on for 48h| After 2 hours of recovery in normal temperature environment, the sensor accuracy meets the specification standard| n=8 c=0
Low temperature storage| -20±2, store without power on for 48h| After 2 hours of recovery in normal temperature environment, the sensor accuracy meets the specification standard| n=8 c=0
High temperature and high humidity storage| 40℃ ±2℃，85%RH±5%RH，48h storage without power supply| After 2 hours of recovery in normal temperature environment, the sensor accuracy meets the specification standard| n=8 c=0
High temperature operation| At 50±2℃, the product will run for 48 hours with power on| After 2 hours of recovery in normal temperature environment, the sensor accuracy meets the specification standard| n=8 c=0
Low temperature operation| At 0±2℃, the product will run for 48 hours with power on| After 2 hours of recovery in normal temperature environment, the sensor accuracy meets the specification standard| n=8 c=0
High and low temperature shock| After keeping at – 20 for 60 minutes, switch to 60 within 10s and keep for another 60 minutes as one cycle, a total of 10 cycles, the sample is not powered on during the test| After 2 hours of recovery in normal temperature environment, the sensor accuracy meets the specification standard| n=8 c=0
Simulating transport vibration| Six-sided vibration, 30 minutes per side, vibration frequency 240rpm| After 2 hours of recovery in normal temperature environment, the sensor accuracy meets the specification standard| n=8 c=0
Package falling| Drop height: set according to the weight-to-height ratio specified in GB/T4857.18. Test according to GB/T4857.5 drop test method for packaging and transport packages. The drop test sequence is one corner, three edges and six faces (if the customer has special requirements, it can be done according to the customer’s requirements).| After the package drop test, the sensor appearance should not be obviously defective, no components should fall off, the sensor should be able to work normally, and the sensor accuracy should meet the specifications.| n=1

box c=0

Revision History

Shenzhen MFrontier Electronics Co., Ltd.
Tel 0755-21386871
Web www.memsf.com

Add 3&5 Floor B2 Building, Zhaoshangju Technology Park, Guangming District, 518107, Shenzhen, China

References

• MFrontier-MEMS sensor, infrared thermopile sensor, infrared pyroelectric sensor, infrared thermopile array sensor, temperature sensor, gas sensor, PM sensor, pressure sensor, infrared filter

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