Peculiar observations between ESP32 and PSE530 Sensor

[kaiii042]

Hi everybody,

I have stumbled across a problem while doing my project. I needed to interface a PSE530 pressure sensor* with the ESP32 and log the data obtained to Excel. The connections for the PSE530 Sensor is shown below:
1. LIVE to 12V from Power Supply
2. GND to GND from Power Supply
3. SIGNAL to ESP32 GPIO Pin 13

The ESP32 is connected to my PC via an USB cable

The code between the sensor and ESP32 is from an online source with a few changes:

// ----------------------------------------------------------------------------
// Sample Sensor Code for use with Data Streamer Excel add-in
// more info available from Microsoft Education Workshop at
// http://aka.ms/hackingSTEM
//
// This project uses an Arduino UNO microcontroller board. More information can
// be found by visiting the Arduino website:
// https://www.arduino.cc/en/main/arduinoBoardUno
//
// This code reads in a generic analog sensor on Arduino pin 0 and prints
// it to serial.
//
// Comments, contributions, suggestions, bug reports, and feature requests
// are welcome! For source code and bug reports see:
// http://github.com/[TODO github path to Hacking STEM]
//
// Copyright 2019, Jen Fox Microsoft EDU Workshop - HackingSTEM
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
// of the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
// ----------------------------------------------------------------------------

// Program variables ----------------------------------------------------------
int exampleVariable;
#define sensorPin 13

// Serial data variables ------------------------------------------------------
//Incoming Serial Data Array
const byte kNumberOfChannelsFromExcel = 6;

// Comma delimiter to separate consecutive data if using more than 1 sensor
const char kDelimiter = ',';
// Interval between serial writes
const int kSerialInterval = 50;
// Timestamp to track serial interval
unsigned long serialPreviousTime;

char* arr[kNumberOfChannelsFromExcel];

// SETUP ----------------------------------------------------------------------
void setup() {
// Initialize Serial Communication
Serial.begin(115200);
pinMode(13, INPUT);
}

// START OF MAIN LOOP ---------------------------------------------------------
void loop()
{
// Gather and process sensor data
processSensors();

// Read Excel variables from serial port (Data Streamer)
// processIncomingSerial();

// Process and send data to Excel via serial port (Data Streamer)
processOutgoingSerial();

// Compares STR1 to STR2 returns 0 if true.
// if ( strcmp ("Apple", arr[0]) == 0){
// Serial.println("working");
// }

delay(200); //records data at 1 sec interval
}

// SENSOR INPUT CODE-----------------------------------------------------------
void processSensors()
{
// Read sensor pin and store to a variable
exampleVariable = analogRead( sensorPin );

// Add any additional raw data analysis below (e.g. unit conversions)
exampleVariable = exampleVariable*244.14; //Converting 4096 units to pascal

}

// Add any specialized methods and processing code below


// OUTGOING SERIAL DATA PROCESSING CODE----------------------------------------
void sendDataToSerial()
{
// Send data out separated by a comma (kDelimiter)
// Repeat next 2 lines of code for each variable sent:

Serial.print(exampleVariable);
Serial.print(kDelimiter);

Serial.println(); // Add final line ending character only once
}

//-----------------------------------------------------------------------------
// DO NOT EDIT ANYTHING BELOW THIS LINE
//-----------------------------------------------------------------------------

// OUTGOING SERIAL DATA PROCESSING CODE----------------------------------------
void processOutgoingSerial()
{
// Enter into this only when serial interval has elapsed
if((millis() - serialPreviousTime) > kSerialInterval)
{
// Reset serial interval timestamp
serialPreviousTime = millis();
sendDataToSerial();
}
}

// INCOMING SERIAL DATA PROCESSING CODE----------------------------------------
void processIncomingSerial()
{
if(Serial.available()){
parseData(GetSerialData());
}
}

// Gathers bytes from serial port to build inputString
char* GetSerialData()
{
static char inputString[64]; // Create a char array to store incoming data
memset(inputString, 0, sizeof(inputString)); // Clear the memory from a pervious reading
while (Serial.available()){
Serial.readBytesUntil('\n', inputString, 64); //Read every byte in Serial buffer until line end or 64 bytes
}
return inputString;
}

// Seperate the data at each delimeter
void parseData(char data[])
{
char *token = strtok(data, ","); // Find the first delimeter and return the token before it
int index = 0; // Index to track storage in the array
while (token != NULL){ // Char* strings terminate w/ a Null character. We'll keep running the command until we hit it
arr[index] = token; // Assign the token to an array
token = strtok(NULL, ","); // Conintue to the next delimeter
index++; // incremenet index to store next value
}
}

By my understanding, i believe the expected output (without addition/reduction of pressure and after processing the raw data obtained) is to show the ambient atmospheric pressure, since the sensor I'm using measures positive pressure. However, the raw data output (i.e. before data processing) I got from the Arduino IDE serial plotter shown in the attachment, is not what I think is the expected output.

Thus, I hope to seek some insights and advice on how I should resolve this.

Cheers!
kaiii

*Datasheet for PSE530 Pressure Sensor: http://content2.smcetech.com/pdf/PSE_5018C.pdf