Write and read I2C on arduino

Hey there,

I want to get the data out of the Sensirion SDP810-125Pa via my arduino. With a llibrary that I downloaded from github, the sensor works fine and gives me data via I2C and the serial moitor respectively with the Arduino IDE.

Now I wanna combine it with Matlab.

clear all
clc
myarduino = arduino('COM3','Uno','Libraries','I2C');
%scanI2CBus(myarduino,0);
pressureSensor = device(myarduino,'I2CAddress',0x25,'bitrate',100000);
write(pressureSensor, 0x361E, 'uint16');
data = read(pressureSensor, 2,'uint16');
disp(data);

I configured the I2CAddress but now it gives me the followin error.

Error using Untitled (line 6)

Error occurred while reading data from the I2C device. Check the connections between the hardware and device, clear the device object and create a

new one.

Thanks for your help!

[Danielle Park]

Hey Benedikt,

Did you ever figure this out? I am trying to do the same but with a Sensirion SLF3S-1300F sensor.

-Danielle

Answer 1

[Aakriti Suman]

I understand that you want to use I2C devices on Arduino hardware.

The address that you are using for I2C communication seems incorrect. The bus address used for I2C comunication on Arduino hardware is 0x48. You can also scan the I2C bus to get the I2C address. You can try the below code snippet.

% connect all the I2C devices with the arduino and then perform the following snippet 
myarduino = arduino('COM4','Uno','Libraries','I2C') % assuming that the arduino hardware is connected in COM4 serial port.
add = scanI2CBus(myarduino);

Here is an example documentation of the usage of I2C devices on arduino hardaware. This will help you in understanding the I2C communication with arduino hardware in detail. https://in.mathworks.com/help/supportpkg/arduinoio/ug/measure-temperature-from-i2c-device-on-arduino-hardware.html

I am also attaching a document which will help you with the functions that can be used in reading and writing to I2C devices connected to arduino hardware. https://in.mathworks.com/help/supportpkg/arduinoio/i2c-sensors.html?s_tid=CRUX_lftnav

[Gongyan Du]

Hi, Aakriti Suman , I want to use INA219 sensor read DC current, but not get result. Help me please!

a=arduino;

INA219='0X40';

INA219_ADC_CH3='43';

i2c=i2cdev(a,INA219);

while 1

getCurrent_mA = read_adc(i2c,hex2dec(INA219_ADC_CH3))

pause(0.5);

end

[Aakriti Suman]

Hii Gongyan,

Can you try 'scanI2CBus' command and get the address for the I2C sensor in a variable and then use that address to get the value of the sensor?

[Gongyan Du]

Hi @Aakriti Summan, My code is:

a=arduino('COM3','uno');

address = scanI2CBus(a,0);

disp(['i2c address: ', address]);

INA219 = '0x40';

Currentsensor = i2cdev(a,INA219);

INA219_ADC_CH0='40'; %CR 40

INA219_ADC_CH1='41'; % Shunt Voltage

INA219_ADC_CH2='42'; % Bus Voltage

INA219_ADC_CH3='43'; % Power

INA219_ADC_CH4='44';% Current

INA219_ADC_CH5='45';%

while 1

disp([' |CR|',' |Shunt V|',' |Bus V|',' |Power|',' |Current|',' |Cal|']);

write(Currentsensor,hex2dec(INA219_ADC_CH0));

read(Currentsensor,3,'uint16');

CR = read(Currentsensor,3,'uint16');

pause(0.1);

write(Currentsensor,hex2dec(INA219_ADC_CH1));

read(Currentsensor,3,'uint16');

V_shunt = read(Currentsensor,3,'uint16');

pause(0.1);

write(Currentsensor,hex2dec(INA219_ADC_CH2));

read(Currentsensor,3,'uint16');

V_bus = read(Currentsensor,3,'uint16');

pause(0.1);

write(Currentsensor,hex2dec(INA219_ADC_CH3));

read(Currentsensor,3,'uint16');

P = read(Currentsensor,3,'uint16');

pause(0.1);

write(Currentsensor,hex2dec(INA219_ADC_CH4));

read(Currentsensor,3,'uint16');

I = read(Currentsensor,3,'uint16');

pause(0.1);

write(Currentsensor,hex2dec(INA219_ADC_CH5));

read(Currentsensor,3,'uint16');

Cal = read(Currentsensor,3,'uint16');

pause(0.1);

disp([CR V_shunt V_bus P I Cal]);

end

[serhat YILDIZHAN]

Hi Gungyan, I will take altitude, temperature and pressure data using the I2C connection with the bmp280 sensor and draw a graph. And I'm thinking of doing this by editing your code. But I couldn't understand some parts of the code. Can you help me?

Currentsensor = i2cdev(a,INA219); %How can I define it according to bmp280?

%Can you explain how you wrote this part?

INA219_ADC_CH0='40'; %CR 40

INA219_ADC_CH1='41'; % Shunt Voltage

INA219_ADC_CH2='42'; % Bus Voltage

INA219_ADC_CH3='43'; % Power

INA219_ADC_CH4='44';% Current

Thank you.

Answer 2

[Benedikt Kniebel]

Hey Danielle,

I just connected the sensor again this morning and reconstructed my setup.

I used the following code on the arduino (and cheked the results in the serial monitor):

#include <Wire.h>
#include <sdpsensor.h>
SDP8XXSensor sdp;

void setup() {
  Wire.begin();
  Serial.begin(9600);
  delay(1000); // let serial console settle
  do {
    int ret = sdp.init();
    if (ret == 0) {
      Serial.print("init(): success\n");
      break;
    } else {
      Serial.print("init(): failed, ret = ");
      Serial.println(ret);
      delay(1000);
    }
  } while(true);
}

void loop() {
  int ret = sdp.readSample();
  if (ret == 0) {
      Serial.print(sdp.getDifferentialPressure());
      Serial.write(13);
      Serial.write(10);
//    Serial.print("Differential pressure: ");
//    Serial.print(" ");
//    Serial.println(sdp.getTemperature());

  } else {
    Serial.print("Error in readSample(), ret = ");
    Serial.println(ret);
  }
  delay(50);
}

This is just retuning the raw pressure sensor data / 20Hz.

Then I followed the steps here:

https://de.mathworks.com/help/matlab/import_export/read-streaming-data-from-arduino.html

Make shure that you insert the correct terminator and COM-Port and maybe lower the if src.UserData.Count > 1001 for a reasonable amount of time between the measurements.

This woks for me and is giving me the serial data from the Arduino.

Hope I could help.

[Danielle Park]

Yes! This is the route I ended up taking as well. Thank you so much!

Answer 3

[Harsha Priya Daggubati]

Hi,

You need to have either a Total Phase Aardvark host adapter or a NI USB-845x adapter board installed to use the i2c interface.

Refer to the following link for installation help:

https://in.mathworks.com/help/instrument/i2c-interface-usage-guidelines.html

You can also follow the steps listed here after the installation is successful:

https://in.mathworks.com/help/instrument/reading-and-writing-data-over-the-i2c-interface.html

These threads might be of help too:

https://in.mathworks.com/help/instrument/troubleshooting-i2c-interface.html

https://in.mathworks.com/help/supportpkg/arduinoio/ug/connection-and-communication-issues.html

[Benedikt Kniebel]

Thanks for your answer.

Are these links just for the direct connection to my computer? I am using the arduino board to read and write to the i2c bus. Like here?

https://www.mathworks.com/help/supportpkg/arduinoio/ug/measure-temperature-from-i2c-device-on-arduino-hardware.html

Is there a difference?

[Harsha Priya Daggubati]

I guess yes. Can you use write as follows similar to the one in the example.

write(pressureSensor, 0x361E, 'uint16');

[Benedikt Kniebel]

That is what I did and it throws the error above.

I also tried to use another I2C bus number.