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Last active November 24, 2022 01:01
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ESPHome Custom Sensor CM1106 CO2
esphome:
name: cm1106_sensor
platform: ESP32
board: wemos_d1_mini32
includes:
- "cm1106.h"
wifi:
ssid: !secret wifi_ssid
password: !secret wifi_pass
# Enable fallback hotspot (captive portal) in case wifi connection fails
ap:
ssid: "CM1106 Fallback Hotspot"
password: "1234567890"
captive_portal:
# Enable logging
logger:
# Enable Home Assistant API
api:
ota:
uart:
rx_pin: GPIO16
tx_pin: GPIO17
baud_rate: 9600
id: cm1106_uart
sensor:
- platform: custom
lambda: |-
auto cm1106Sensor = new CM1106Sensor(id(cm1106_uart), 10000);
App.register_component(cm1106Sensor);
return {cm1106Sensor};
sensors:
- name: "CO₂ Sensor"
accuracy_decimals: 0
unit_of_measurement: "ppm"
icon: "mdi:molecule-co2"
switch:
- platform: custom
lambda: |-
auto cm1106Calib = new CM1106CalibrateSwitch(id(cm1106_uart));
App.register_component(cm1106Calib);
return {cm1106Calib};
switches:
- name: "CM1106 Zero Calibration"
// put this file in your esphome folder
// protocol implemented as described in https://en.gassensor.com.cn/Product_files/Specifications/CM1106-C%20Single%20Beam%20NDIR%20CO2%20Sensor%20Module%20Specification.pdf
#include "esphome.h"
class CM1106 : public UARTDevice {
public:
CM1106(UARTComponent *parent) : UARTDevice(parent) {}
void setCo2CalibValue(uint16_t ppm = 400) {
uint8_t cmd[6];
memcpy(cmd, CM1106_CMD_SET_CO2_CALIB, sizeof(cmd));
cmd[3] = ppm >> 8;
cmd[4] = ppm & 0xFF;
uint8_t response[4] = {0};
bool success = sendUartCommand(CM1106_CMD_SET_CO2_CALIB, sizeof(CM1106_CMD_SET_CO2_CALIB), response, sizeof(response));
if(!success) {
ESP_LOGW(TAG, "Reading data from CM1106 failed!");
return;
}
// check if correct response received
if(memcmp(response, CM1106_CMD_SET_CO2_CALIB_RESPONSE, sizeof(response)) != 0) {
ESP_LOGW(TAG, "Got wrong UART response: %02X %02X %02X %02X", response[0], response[1], response[2], response[3]);
return;
}
ESP_LOGD(TAG, "CM1106 Successfully calibrated sensor to %uppm", ppm);
}
int16_t getCo2PPM() {
uint8_t response[8] = {0}; // response: 0x16, 0x05, 0x01, DF1, DF2, DF3, DF4, CRC. PPM: DF1*256+DF2
bool success = sendUartCommand(CM1106_CMD_GET_CO2, sizeof(CM1106_CMD_GET_CO2), response, sizeof(response));
if(!success) {
ESP_LOGW(TAG, "Reading data from CM1106 failed!");
return -1;
}
if(!(response[0] == 0x16 && response[1] == 0x05 && response[2] == 0x01)) {
ESP_LOGW(TAG, "Got wrong UART response: %02X %02X %02X %02X...", response[0], response[1], response[2], response[3]);
return -1;
}
uint8_t checksum = calcCRC(response, sizeof(response));
if(response[7] != checksum) {
ESP_LOGW(TAG, "Got wrong UART checksum: 0x%02X - Calculated: 0x%02X", response[7], checksum);
return -1;
}
int16_t ppm = response[3] << 8 | response[4];
ESP_LOGD(TAG, "CM1106 Received CO₂=%uppm DF3=%02X DF4=%02X", ppm, response[5], response[6]);
return ppm;
}
private:
const char *TAG = "cm1106";
uint8_t CM1106_CMD_GET_CO2[4] = {0x11, 0x01, 0x01, 0xED}; // head, len, cmd, [data], crc
uint8_t CM1106_CMD_SET_CO2_CALIB[6] = {0x11, 0x03, 0x03, 0x00, 0x00, 0x00};
uint8_t CM1106_CMD_SET_CO2_CALIB_RESPONSE[4] = {0x16, 0x01, 0x03, 0xE6};
// Checksum: 256-(HEAD+LEN+CMD+DATA)%256
uint8_t calcCRC(uint8_t* response, size_t len) {
uint8_t crc = 0;
// last byte of response is checksum, don't calculate it
for(int i = 0; i < len - 1; i++) {
crc -= response[i];
}
return crc;
}
bool sendUartCommand(uint8_t *command, size_t commandLen, uint8_t *response = nullptr, size_t responseLen = 0) {
// Empty RX Buffer
while (available()) {
read();
}
// calculate CRC
command[commandLen - 1] = calcCRC(command, commandLen);
write_array(command, commandLen);
flush();
if(response == nullptr) {
return true;
}
return read_array(response, responseLen);
}
};
class CM1106Sensor : public PollingComponent, public Sensor {
private:
CM1106 *cm1106;
public:
CM1106Sensor(UARTComponent *parent, uint32_t update_interval) : PollingComponent(update_interval) {
cm1106 = new CM1106(parent);
}
float get_setup_priority() const { return setup_priority::DATA; }
void setup() override {
}
void update() override {
int16_t ppm = cm1106->getCo2PPM();
if(ppm > -1) {
publish_state(ppm);
}
}
};
class CM1106CalibrateSwitch : public Component, public Switch {
private:
CM1106 *cm1106;
public:
CM1106CalibrateSwitch(UARTComponent *parent) {
cm1106 = new CM1106(parent);
}
void write_state(bool state) override {
if(state) {
publish_state(state);
cm1106->setCo2CalibValue();
turn_off();
}
else {
publish_state(state);
}
}
};
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