i2c communication of esp32 with Sensirion SFM3000-D air flow sensor.

[csce5612]

This is the following code I have run to get the values from the airflow sensor, I got constant values (239.54). But I need to read the volume data from the airflow sensor for each second.
Please help me out in rectifying my code to get the results. I got this from the Arduino forum.
I am using espressif esp32-wrooom-32UE development kit
Here is the datasheet for esp32
[](https://www.espressif.com/sites/default/files/documentation/esp32-wroom-32e_esp32-wroom-32ue_datasheet_en.pdf)
datasheet for sensor
https://www.mouser.com/datasheet/2/682/Sensirion_Mass_Flow_Meters_SFM3400_Datasheet-1853359.pdf

after running i2c scanner for esp32 and sensirion airflow sensor
I got two addresses 1. 64 (0x40) 2. 118 (0x76)

#include <Wire.h>

void setup()
{
Wire.begin();
Serial.begin(9600);
int a = 0;
int b = 0;
int c = 0;

delay(1000);

Wire.beginTransmission(byte(0x40)); // transmit to device #64 (0x40)
Wire.write(byte(0x10)); //
Wire.write(byte(0x00)); //
Wire.endTransmission();

delay(5);

Wire.requestFrom(0x40, 3); //
a = Wire.read(); // first received byte stored here
b = Wire.read(); // second received byte stored here
c = Wire.read(); // third received byte stored here
Wire.endTransmission();
Serial.print(a);
Serial.print(b);
Serial.println(c);

delay(5);

Wire.requestFrom(0x40, 3); //
a = Wire.read(); // first received byte stored here
b = Wire.read(); // second received byte stored here
c = Wire.read(); // third received byte stored here
Wire.endTransmission();
Serial.print(a);
Serial.print(b);
Serial.println(c);

delay(5);
}

uint8_t crc8(const uint8_t data, uint8_t crc) {
crc ^= data;

for ( uint8_t i = 8; i; --i ) {
crc = ( crc & 0x80 )
? (crc << 1) ^ 0x31
: (crc << 1);
}
return crc;
}

void loop() {

int offset = 32000; // Offset for the sensor
float scale = 140.0; // Scale factor for Air and N2 is 140.0, O2 is 142.8

Wire.requestFrom(0x40, 3); // read 3 bytes from device with address 0x40
uint16_t a = Wire.read(); // first received byte stored here. The variable "uint16_t" can hold 2 bytes, this will be relevant later
uint8_t b = Wire.read(); // second received byte stored here
uint8_t crc = Wire.read(); // crc value stored here
uint8_t mycrc = 0xFF; // initialize crc variable
mycrc = crc8(a, mycrc); // let first byte through CRC calculation
mycrc = crc8(b, mycrc); // and the second byte too
if (mycrc != crc) { // check if the calculated and the received CRC byte matches
//Serial.println("Error: wrong CRC");
}
a = (a << 8) | b; // combine the two received bytes to a 16bit integer value
// a >>= 2; // remove the two least significant bits
float Flow = ((float)a - offset) / scale;
//Serial.println(a); // print the raw data from the sensor to the serial interface
Serial.println(Flow); // print the calculated flow to the serial interface

delay(2500);
}

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