read/write internal register of CO2 NDIR sensor 'SCD30'

Using Arduino Sensors
1

I'm attaching sensor spec sheet, and I'm trying to get CO2 concentration in ppm. No other data required.
I'm using I2C protocol with Arduino UNO board.

I got 0x61 as a device address, so I used that in the code i wrote below.

#include <Wire.h>

void setup()
{
Wire.begin();
Serial.begin(19200);
}

void loop()
{
Wire.requestFrom(0x61,2);

while(Wire.available())
{
byte c = Wire.read();
Serial.print(c); Serial.print("\n");Serial.print("\n");
}

delay(500);
}

For calibration, need to change ASC(auto-calibration) condition and FRC(forced calibration) condition, with the arguments showed in data sheet. I've never red or written an internal register value of sensor, so I'm having trouble to understand Wire.read and Wire.write functions. Do registers have their own addresses and values?

For example, I could find "Write Header", "Cmd MSB", "Cmd LSB",.... So, Do they have own address I couldn't find?

So, for the tables I'm attaching as PNG files.

  • Is "Write Header" a given name from developers?
  • Does it have a certain address?
  • Is 0xC2 the value what "Write Header" has?
  • I could find using beginTransmission(address) function for communicating with sensor registers, the "address" means a certain hex value of "ASC MSB" or "ASC LSB"?

SCD30 protocol1.PNG
SCD30 protocol1.PNG928×167 20.3 KB

SCD30 protocol2.PNG

co2_Sensirion_SCD30_Protocol.pdf (1.1 MB)

SCD30 protocol1.PNG
SCD30 protocol1.PNG928×167 20.3 KB

SCD30 protocol2.PNG

2

Lets backup a notch, load the I2C scanner and see if it is where you think it is. Also do you have the pull up resistors on the I2C. either of these would give you the problems you see. Is your clock 100 kHz or less, maybe slowing it will help, a lot depends on your hardware layout. Next time you might include a schematic, not a fritzy thing. Be sure the voltages are correct.

3

Manufacturer's page: CO₂.

Sparkfun page: CO₂ Humidity and Temperature Sensor - SCD30 - SEN-15112 - SparkFun Electronics.

Sparkfun library: GitHub - sparkfun/SparkFun_SCD30_Arduino_Library: An Arduino library for the SCD30 NDIR CO2 sensor..

I took a quick look at it, and I think you may not connect the Arduin Uno with its 5V I2C bus to the module. The maximum voltage on its SDA and SCL pins is 3.0V.