dt/co2_sniffer.ino

## co2_sniffer.ino
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266mDNS.h>
#include <ESP8266HTTPClient.h>
#include <ESP8266WebServer.h>
#include <ArduinoOTA.h>

#include <SoftwareSerial.h>

byte cmdRead[2] = {0x86, 0x00};
byte cmdCalibrateZero[2] = {0x87, 0x00};
byte cmdEnableABC[2] = {0x79, 0xA0};
byte cmdDisableABC[2] = {0x79, 0x00};
byte cmdReset[2] = {0x8d, 0x00};

const int rx_pin = 4;
const int tx_pin = 5;

SoftwareSerial sensor(rx_pin, tx_pin, false, 256);

const char* ssid = "<my-wifi-ssid>";
const char* password = "<my-wifi-password>";


ESP8266WebServer server ( 80 );
HTTPClient http;

void setup(void)
{
  Serial.begin(115200);
  delay(100);

  sensor.begin(9600); // init CO2 sensor serial port

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  Serial.println("");

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  server.on ( "/", handleRoot );
  server.begin();

  Serial.println("webserver started");
  MDNS.addService("http", "tcp", 80);

  ArduinoOTA.setHostname("sniffer");
  ArduinoOTA.begin();

  delay(5000);
  sendCmd(cmdDisableABC);
}

void handleRoot() {
  String page = String(
    "<html><head><meta charset='utf-8'/>"
    "<meta http-equiv=\"refresh\" content=\"60\" />"
    "<title>Sniffer</title>"
    "<link href='https://fonts.googleapis.com/icon?family=Material+Icons' rel='stylesheet'/>"
    "<style>"
    "body { font-family: Helvetica, Arial, Sans-Serif; background-color: #eee; }"
    "</style>"
    "<meta name='viewport' content='width = device-width, initial-scale = 1.0, maximum-scale = 1.0, user-scalable=0'>"
    "</head>"
    "<body>\n"
    "<div class='sniffer'>\n"
      "<p>CO2: "+String(sendCmd(cmdRead)) +" ppm </p>"
    "</div>" //  /stc
    "</body></html>"
  );
  server.send(200, "text/html", page);
}

void logToInflux() {
  int ppm = sendCmd(cmdRead);
  Serial.print("CO2: ");
  Serial.print(ppm);
  Serial.println("ppm");

  if (ppm < 1) {
    return;
  }

  http.begin("<my-logging-service>");
  int httpCode = http.POST(String("co2 ppm="+String(ppm)));

  if(httpCode > 299) {
    Serial.print("Reply(");
    Serial.print(httpCode);
    Serial.print("): ");
    Serial.print(http.getString());
  }
  http.end();
}

unsigned long lastReport;
unsigned long nextReport;
uint32 ticks;

void loop() {
  ArduinoOTA.handle();
  server.handleClient();

  ticks++;
  if (ticks > 10000) {
    ticks = 0;
    unsigned long now = millis();
    if (now > nextReport || now < lastReport) {
       nextReport = now + 1000 * 30;
       logToInflux();
       lastReport = now;
    }
  }
}

byte checksum(byte *array)
{
  byte checksum = 0;
  for (byte i = 1; i < 8; i++)
    checksum+=array[i];
  checksum = 0xFF - checksum;
  return (checksum+1);
}


unsigned int sendCmd(byte* cmd) {
  byte req[9];
  memset(req, 0, 9);
  req[0] = 0xFF;
  req[1] = 0x01;
  req[2] = cmd[0];
  req[3] = cmd[1];
  req[8] = checksum(req);

  bool header_found = false;
  sensor.write(req, 9);

  if (cmd[0] != cmdRead[0]) {
    return 0;
  }

  // read until we see the first two bytes of the reply.
  while (sensor.available() && (!header_found)) {
    if (sensor.read() == 0xff ) {
      if (sensor.read() == 0x86 ) {
        header_found = true;
      }
    }
  }

  if (!header_found) {
    Serial.println("conn closed before header not found");
    return 0;
  }

  // already read first two bytes while looking for the beginning so
  // a) put those in the buffer so the checksum matches
  // b) read the remaining 9-2=7 bytes into the buffer.
  unsigned char resp[9];
  memset(resp, 0, 9);
  resp[0] = 0xff;
  resp[1] = 0x86;
  sensor.readBytes(&resp[2], 7);

  // Check that the checksum matches.
  byte crc = checksum(resp);
  if ( !(resp[8] == crc) ) {
    Serial.println(String("CO2: CRC error: ") + String(crc) + String(" vs ") + String(resp[8]));
    return 0;
  }

  // Compute the result.
  unsigned int ppmHigh = (unsigned int) resp[2];
  unsigned int ppmLow = (unsigned int) resp[3];
  unsigned int ppm = (256 * ppmHigh) + ppmLow;
  return ppm;
}
	#include <ESP8266WiFi.h>
	#include <WiFiClient.h>
	#include <ESP8266mDNS.h>
	#include <ESP8266HTTPClient.h>
	#include <ESP8266WebServer.h>
	#include <ArduinoOTA.h>

	#include <SoftwareSerial.h>

	byte cmdRead[2] = {0x86, 0x00};
	byte cmdCalibrateZero[2] = {0x87, 0x00};
	byte cmdEnableABC[2] = {0x79, 0xA0};
	byte cmdDisableABC[2] = {0x79, 0x00};
	byte cmdReset[2] = {0x8d, 0x00};

	const int rx_pin = 4;
	const int tx_pin = 5;

	SoftwareSerial sensor(rx_pin, tx_pin, false, 256);

	const char* ssid = "<my-wifi-ssid>";
	const char* password = "<my-wifi-password>";


	ESP8266WebServer server ( 80 );
	HTTPClient http;

	void setup(void)
	{
	Serial.begin(115200);
	delay(100);

	sensor.begin(9600); // init CO2 sensor serial port

	WiFi.mode(WIFI_STA);
	WiFi.begin(ssid, password);
	Serial.println("");

	while (WiFi.status() != WL_CONNECTED) {
	delay(500);
	Serial.print(".");
	}
	Serial.println("");
	Serial.print("Connected to ");
	Serial.println(ssid);
	Serial.print("IP address: ");
	Serial.println(WiFi.localIP());

	server.on ( "/", handleRoot );
	server.begin();

	Serial.println("webserver started");
	MDNS.addService("http", "tcp", 80);

	ArduinoOTA.setHostname("sniffer");
	ArduinoOTA.begin();

	delay(5000);
	sendCmd(cmdDisableABC);
	}

	void handleRoot() {
	String page = String(
	"<html><head><meta charset='utf-8'/>"
	"<meta http-equiv=\"refresh\" content=\"60\" />"
	"<title>Sniffer</title>"
	"<link href='https://fonts.googleapis.com/icon?family=Material+Icons' rel='stylesheet'/>"
	"<style>"
	"body { font-family: Helvetica, Arial, Sans-Serif; background-color: #eee; }"
	"</style>"
	"<meta name='viewport' content='width = device-width, initial-scale = 1.0, maximum-scale = 1.0, user-scalable=0'>"
	"</head>"
	"<body>\n"
	"<div class='sniffer'>\n"
	"<p>CO2: "+String(sendCmd(cmdRead)) +" ppm </p>"
	"</div>" // /stc
	"</body></html>"
	);
	server.send(200, "text/html", page);
	}

	void logToInflux() {
	int ppm = sendCmd(cmdRead);
	Serial.print("CO2: ");
	Serial.print(ppm);
	Serial.println("ppm");

	if (ppm < 1) {
	return;
	}

	http.begin("<my-logging-service>");
	int httpCode = http.POST(String("co2 ppm="+String(ppm)));

	if(httpCode > 299) {
	Serial.print("Reply(");
	Serial.print(httpCode);
	Serial.print("): ");
	Serial.print(http.getString());
	}
	http.end();
	}

	unsigned long lastReport;
	unsigned long nextReport;
	uint32 ticks;

	void loop() {
	ArduinoOTA.handle();
	server.handleClient();

	ticks++;
	if (ticks > 10000) {
	ticks = 0;
	unsigned long now = millis();
	if (now > nextReport \|\| now < lastReport) {
	nextReport = now + 1000 * 30;
	logToInflux();
	lastReport = now;
	}
	}
	}

	byte checksum(byte *array)
	{
	byte checksum = 0;
	for (byte i = 1; i < 8; i++)
	checksum+=array[i];
	checksum = 0xFF - checksum;
	return (checksum+1);
	}


	unsigned int sendCmd(byte* cmd) {
	byte req[9];
	memset(req, 0, 9);
	req[0] = 0xFF;
	req[1] = 0x01;
	req[2] = cmd[0];
	req[3] = cmd[1];
	req[8] = checksum(req);

	bool header_found = false;
	sensor.write(req, 9);

	if (cmd[0] != cmdRead[0]) {
	return 0;
	}

	// read until we see the first two bytes of the reply.
	while (sensor.available() && (!header_found)) {
	if (sensor.read() == 0xff ) {
	if (sensor.read() == 0x86 ) {
	header_found = true;
	}
	}
	}

	if (!header_found) {
	Serial.println("conn closed before header not found");
	return 0;
	}

	// already read first two bytes while looking for the beginning so
	// a) put those in the buffer so the checksum matches
	// b) read the remaining 9-2=7 bytes into the buffer.
	unsigned char resp[9];
	memset(resp, 0, 9);
	resp[0] = 0xff;
	resp[1] = 0x86;
	sensor.readBytes(&resp[2], 7);

	// Check that the checksum matches.
	byte crc = checksum(resp);
	if ( !(resp[8] == crc) ) {
	Serial.println(String("CO2: CRC error: ") + String(crc) + String(" vs ") + String(resp[8]));
	return 0;
	}

	// Compute the result.
	unsigned int ppmHigh = (unsigned int) resp[2];
	unsigned int ppmLow = (unsigned int) resp[3];
	unsigned int ppm = (256 * ppmHigh) + ppmLow;
	return ppm;
	}