MHZ16 Class Reference

C++ API support for the Grove CO2 sensor. More...

Detailed Description

• ID: mhz16
• Name: Grove CO2 sensor
• Category: gaseous
• Manufacturer: seeed
• Connection: uart

This class implements support for the Grove CO2 sensor.

It's CO2 detection ranges from 0PPM to 2000PPM. It requires a 2-3 minute warm up time before reporting valid data.

  // Instantiate a MHZ16 serial CO2 sensor on uart 0.
  // This example was tested on the Grove CO2 sensor module.

  upm::MHZ16* co2 = new upm::MHZ16(0);
  
  // make sure port is initialized properly.  9600 baud is the default.
  if (!co2->setupTty(B9600))
    {
      cerr << "Failed to setup tty port parameters" << endl;
      return 1;
    }
  
  cout << "Make sure that the sensor has had at least 3 minutes to warm up" 
       << endl;
  cout << "or you will not get valid results." << endl;
  cout << "The temperature reported is not the ambient temperature, " << endl;
  cout << "but rather the temperature of the sensor elements." << endl;

  sleep(1);

  int gas;
  int temp;

  while (shouldRun)
    {
      co2->getData(&gas, &temp);
      cout << "CO2 concentration: " << gas << " PPM, "
           << "Temperature (in C): " << temp <<endl;

      sleep(2);
    }

Public Member Functions
	MHZ16 (int uart)
	~MHZ16 ()
bool	dataAvailable (unsigned int millis)
int	readData (char *buffer, size_t len)
int	writeData (char *buffer, size_t len)
bool	setupTty (speed_t baud=B9600)
bool	verifyPacket (unsigned char *pkt)
bool	getData (int *gas, int *temp)
void	calibrateZeroPoint ()

Protected Member Functions
int	ttyFd ()
int	setTtyFd (int fd)

Constructor & Destructor Documentation

MHZ16

(

int

uart

)

MHZ16 module constructor

Parameters

uart	default uart to use (0 or 1)

~MHZ16

(

)

MHZ16 module Destructor

Member Function Documentation

bool dataAvailable

(

unsigned int

millis

)

Check to see if there is data available for reading

Parameters

millis

number of milliseconds to wait, 0 means no wait.

Returns

true if there is data available to be read

int readData	(	char *	buffer,
		size_t	len
	)

read any available data into a user-supplied buffer. Note, the call will block until data is available to be read. Use dataAvailable() to determine whether there is data available beforehand, to avoid blocking.

Parameters

buffer	the buffer to hold the data read
len	the length of the buffer

Returns

the number of bytes read

int writeData	(	char *	buffer,
		size_t	len
	)

write the data in buffer to the device

Parameters

buffer	the buffer to hold the data read
len	the length of the buffer

Returns

the number of bytes written

bool setupTty

(

speed_t

baud = B9600

)

setup the proper tty i/o modes and the baudrate. The default baud rate is 9600 (B9600).

Parameters

baud	the desired baud rate.

Returns

true if successful

bool verifyPacket

(

unsigned char *

pkt

)

verify the packet header and indicate it's validity

Parameters

pkt	the packet to check

Returns

true if valid checksum, false otherwise

bool getData	(	int *	gas,
		int *	temp
	)

Query the sensor and return gas (CO2) concentration and temperature data.

Parameters

gas	the returned gas concentration
temp	the returned temperature in celsius

Returns

true if successful

void calibrateZeroPoint

(

)

Set the zero point of the sensor

---

The documentation for this class was generated from the following files:

• /var/lib/jenkins/workspace/upm-doc-stable/src/mhz16/mhz16.h
• /var/lib/jenkins/workspace/upm-doc-stable/src/mhz16/mhz16.cxx