SPECIFICATION Preliminary Version (Software Version: V0.08_9A02) Product Name: Dual IR Sources NDIR CO2 Sensor Module Item No.: CM1109 Version: V0.8

Dual IR Sources NDIR CO2 Sensor Module CM1109 Applications ▪ HVAC, central air conditioning ▪ Agricultural planting, plant cultivation ▪ Storage, cold chain transportation ▪ Indoor air quality detector Description CM1109 is a carbon dioxide sensor based on the new patented two-engine technology and independent intellectual property rights of non-spectrophotometric infrared detection principle. The life of sensor become longer, at the same time, It avoids the influence of temperature and humidity, light source aging and other factors on the sensor measurement accuracy. Better stability and reliability...

Typical Application Circuit Application scene: UART_TTL serial port output Description of Calibration Auto Calibration: Rough installing and influence of transportation might result in reducing of sensor measuring accuracy and baseline drift, sensor will correct the drift by the built-in self-correcting logic. Powering on the sensor for 7 days continuously, it will record the lowest CO2 concentration measurement value during the 7 days, which will be regarded as baseline (400ppm) when sensor do auto calibration after the 7 days working. In order to ensure correct auto calibration, please make...

PWM Output PWM cycle: 1004ms Positive pulse width: 0-5000: (PPM/5) + 2ms CO2 concentration detection value: 5000ppm range: (PWM Positive pulse width -2) *5 PWM output schema: Note Connect the pin of PWM to the oscilloscope. Add a pull-up resistor around 5K-10K between the pin of PWM and power supply.

Product Installation 1. In order to ensure airflow diffusion into the sensor inner, make sure the minimum distance between the area of waterproof filter and the other components is 1.5 mm, otherwise, quick response time of the sensor will be effected. Reference as below: Waterproof Filter 2. To avoid the influence of stress on sensor, please soldering by hand as much as possible when mounting the sensor to the PCB. Reference as below:

1).The data in this protocol is all hexadecimal data. Example: “46” for decimal [70]. 2). Baud rate: 9600, Data Bits: 8, Stop Bits: 1, Parity: No, Flow control: No. 3). [x x] is for single-byte data (unsigned, 0-255); for double data, high byte is in front of low byte. Sending format of test software:

4.1 Read Measured Result of CO2 Send: 11 01 01 ED Response: 16 05 01 DF1- DF4 [CS] Function: Read measured result of CO2 (Unit: ppm) Note: CO2 measured result = DF1*256+DF2 DF3 DF4 is reserved Example: Response: 16 05 01 02 58 00 00 8A Explanation: Hex is converted to decimal: 02 is 02; 58 is 88 CO2 concentration =02*256+88 = 600ppm 4.2 Open/Close ABC and Set ABC Parameter Send: 11 07 10 DF1 DF2 DF3 DF4 DF5 DF6 CS Response: 16 01 10 D9 Explanation: DF1: reserved, default 100 (0x64) DF2: open/close auto calibration (0: open; 2: close) DF3: calibration cycle (1-30 days optional, default is 7 days)...

4.2.3 Change the Calibration Cycle The calibration cycle is 7 days by default. For example, if you want to change the calibration cycle to 10 days, you should set the DF3=10. Example: Send: 11 07 10 64 00 0A 01 90 64 75 Response: 16 01 10 D9 4.3 Calibration of CO2 Concentration Send: 11 03 03 DF1 DF2 CS Response: 16 01 03 E6 Function: Calibration of CO2 concentration Note: 1. Calibration target value = DF1*256+DF2 Unit: PPM, range (400-1500ppm) 2. Before calibration, please make sure CO2 concentration in current ambient is calibration target value. Keeping this CO2 concentration for two 2 minutes,...

1. Timing Diagram Introduction 1.1 Common Description a. This protocol is based on standard I2C timing sequence, the clock frequency is 10kHz～400kHz. b. Use big-endian format, the most significant bit to be sent first. 1.2 I2C Sequence Diagram Introduction Parameter fSCL (SCL clock frequency) tHD.STA (hold time of the starting bit) tSU.STA (setup time of the starting bit) tHD.DAT (hold time of the data) tSU.DAT (setup time of the data ) tSU.STO (setup time of the stop bit) Note: SCL clock frequency is generated by the master device with the range 10khz～400khz. 1.3 Basic Data Transmission Formats...

The meaning of the symbol in picture 1.2 and picture 1.3: S: start condition SA: slave address W: write bit R: read bit A: acknowledge bit ~A: not acknowledge bit D: data, each data is 8bit P: stop condition Shadow: The signal generated from the master device No Shadow: The signal generated from the slave device 1.4 Timing Diagram Picture 4: The address byte sent from the master device Picture 5: The master device read a byte from the slave device 1.5 Notes The performance of the MCU which is used in the sensor is not very high. If you use I/O port to simulate I²C master device, it is suggested...

CO2 measuring result: DF0*256+DF1, Fixed output is 550ppm during preheating period Status bit: 0: Preheating; 1: Normal operation; 2: Operating trouble; 3: Out of FS, 5: Non-calibrated Example: The master device reads some data: Read 3 bit. 0x01 0x03 0x20 0x01 0xDB CO2 measuring result = (0x03 0x20) hexadecimal = (800) decimal = 800 ppm Status bit: 0x01 means working normally [CS]= -(0x01 +0x03+0x20+0x01) Only keep the lowest bite.

2.3 Auto Zero Setting Specification Setting Send: 0x10 [DF0] [DF1] [DF2] [DF3] [DF4] [DF5] Response: [0x10] [DF0] [DF1] [DF2] [DF3] [DF4] [DF5] [CS] Format description: 1. Sensor will be auto calibration specification setting status after receiving command 0x10. After this, all the data which I2C read are the data in this status format, until sensor receives new command or repowering on. 2. Data format, the master will receive [DF0] firstly, and receive [CS] at last. The result is calculated by high bit in front 2.5 Read the Serial Number of the Sensor Send: 0x1F Response: [0x1F] [DF0] [DF1]...

Decimal Effective Reading Value Integer type Integer type Integer type Integer type Integer type 3. Five integers form a 20-bit code. 2.6 Read Software Version Send: 0x1E Response: [0x1E] [DF0] [DF1] [DF2] [DF3] [DF4] [DF5] [DF6] [DF7] [DF8] [DF9] [CS] Note: 1. Sensor starts software version output status once receiving the command 0x1E. After this, all the data which I2C read will be such status format data, until the sensor receives new command or re-powering on. 2. Data format, the master device receives DF0 first, and then receives CS at last. [DF0 ] …… [DF9 ] is ASCII. 3. Communication Diagram...