I2C interface HCLA pressure sensors (Value doesn't change)

Other Hardware Sensors
1

Hello people!!

I am in a bit need of a support yet again!!

Well I am just writing an I2C interface for communicating and reading digital pressure values from HCLA02X5EB (amplified pressure sensors range) sensor from SensorTechnics (First-Sensors) using ARDUINO UNO board.

I am attaching the used sketch for the communication I have been able to develop using the help from the forums.

Now the problem is.. That the sensor is constantly showing a fixed pressure value on the Serial monitor.. Even if I blow air into the port the value does not change.. I have also tried changing the sensors with brand new... but the problem persist...

As given in the I2C application note (http://www.first-sensor.com/cms/upload/appnotes/AN_I2C-Bus_HMI_HDI_HCLA_HCA_SSI_E_11155.pdf), I have also checked the analog output of the sensor.. But surprisingly it shows also a fixed value of 2.23-2.25 V

This voltage, according to the datasheet (http://www.first-sensor.com/cms/upload/datasheets/DS_Standard-HCLA_E_11629.pdf), is the default zero-offset

What is it going wrong here...

Please help!!

Deeply appreciate your support! :slight_smile: :slight_smile:

Regards

Pramit

I am totally confused about the reason for this problem

Pressure_sensor_check.ino (1.59 KB)

2

Please post your code within code tags (</> above the smileys). Many people on the forum will not download attached code. The reason can be that they have a phone or tablet that can't run the IDE to view your code. For me, I just don't want another folder in my sketchbook which will be created if I download the code to view in my IDE.

Have you ran an I2C scanner to verify the address of and communication with your sensor?

3

Ahh ok...

Thanks so much for the insight... :slight_smile: Here is the code

#include <Wire.h>

float pressure_diff = 0;
int P_counts_diff;        // 16bit value
float sensitivity_p_diff = 0;
byte byte_MSB;
byte byte_LSB;
#define P_min_diff -25       // min. for the differential pressure sensor
#define P_max_diff 25     // max. for the differential pressure sensor
#define press_sensor 0x78
#define Out_min 1638     // min. counts for the sensors (same for both sensors)
#define Out_max 27852 // max. counts for the sensors (same for both sensors)


void setup(){
  Serial.begin(9600);
 // delay(1000);
  Wire.begin();
}

float read_press (){
    // initiate measurement
  Wire.beginTransmission(press_sensor);
  Wire.write(0);
  Wire.available();
  int Ack = Wire.read(); // receive a byte
  Wire.endTransmission(); 
  delay(1000); //This particular delay is the delay between the displayed values (in msec)...

  // READ DATA from here on
  Wire.beginTransmission(press_sensor);
  Wire.requestFrom(press_sensor,2);  //Reade 1 byte
  Wire.available();
  byte_MSB = Wire.read(); // receive most significant byte
  byte_LSB = Wire.read(); // receive least significant byte
  P_counts_diff = ((int)byte_MSB << 8) | byte_LSB; // Putting both bytes together
  sensitivity_p_diff = (Out_max - Out_min)/(P_max_diff - P_min_diff); // calculate the differential pressure sensors sensitivity
  pressure_diff = (P_counts_diff - Out_min)/sensitivity_p_diff + P_min_diff;   // calculate the differential pressure in [mbar]
  return pressure_diff;
  Wire.endTransmission();
}

void loop(){
  float Differential_pressure = read_press();
  Serial.print("pressure in mBar : ");
  Serial.println(Differential_pressure);
}

Yes I have run the I2C scanner... And there is a peculiar thing I have noticed that it shows two addresses for the same sensor.. 0x78 (which is default) and another which is programmed...

This other address is somehow fishy.. because if I open a new sensor, it should work on the default address only...

Any comments?

Pramit

4 
Test this:



#include <Wire.h>

float pressure_diff = 0;
int P_counts_diff;        // 16bit value
float sensitivity_p_diff = 0;
word byte_MSB;
byte byte_LSB;
#define P_min_diff -12.5       // min. for the differential pressure sensor
#define P_max_diff 12.5     // max. for the differential pressure sensor
#define press_sensor 0x78
#define Out_min 1638     // min. counts for the sensors (same for both sensors)
#define Out_max 27852 // max. counts for the sensors (same for both sensors)


void setup(){
  Serial.begin(9600);
 // delay(1000);
  Wire.begin();
}

float read_press (){
    // initiate measurement
  /*wire.beginTransmission(press_sensor);
  Wire.write(0);
  Wire.available();
  int Ack = Wire.read(); // receive a byte
  Wire.endTransmission();*/ 
  delay(1000); //This particular delay is the delay between the displayed values (in msec)...

  // READ DATA from here on
  Wire.beginTransmission(press_sensor);
  Wire.requestFrom(press_sensor,2);  //Reade 1 byte
  Wire.available();
  byte_MSB = Wire.read(); // receive most significant byte
  byte_LSB = Wire.read(); // receive least significant byte
  P_counts_diff = 0;
  P_counts_diff = ((int)(byte_MSB << 8 | byte_LSB)); // Putting both bytes together
  //Serial.print(P_max_diff - P_min_diff);
  sensitivity_p_diff = (Out_max - Out_min)/(P_max_diff - P_min_diff); // calculate the differential pressure sensors sensitivity
  pressure_diff = (P_counts_diff - Out_min)/sensitivity_p_diff + P_min_diff;   // calculate the differential pressure in [mbar]
  return pressure_diff;
  Wire.endTransmission();
}

void loop(){
  float Differential_pressure = read_press();
  Serial.print("pressure in mBar : ");
  Serial.println(Differential_pressure);
}