Arduino Nano 33 IoT serial monitor is not updating

[kira887]

How to modify this code to make the serial monitor update the value. I have used similar code with the SoftwareSerial library with Arduino Uno and Maga2560. but when I use the following code with Arduino Nono 33 Iot, the serial monitor show results as in the picture

#include <Arduino.h>
#include "wiring_private.h"

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
 
#define SCREEN_WIDTH 128    // OLED display width, in pixels
#define SCREEN_HEIGHT 64    // OLED display height, in pixels
#define OLED_RESET -1       // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
 
#define RE 8
#define DE 7

// Modbus RTU requests for reading NPK values
const byte nitro[] = {0x01,0x03, 0x00, 0x04, 0x00, 0x01, 0xC5, 0xCB}; 
const byte phos[] = {0x01,0x03, 0x00, 0x05, 0x00, 0x01, 0x94, 0x0B}; 
const byte pota[] = {0x01,0x03, 0x00, 0x06, 0x00, 0x01, 0x64, 0x0B};

// A variable used to store NPK values
byte values[1];


Uart mySerial (&sercom0, 2, 3, SERCOM_RX_PAD_1, UART_TX_PAD_0);



// Attach the interrupt handler to the SERCOM
void SERCOM0_Handler()
{
    mySerial.IrqHandler();
}

void setup() {
  // Reassign pins 5 and 6 to SERCOM alt
  pinPeripheral(2, PIO_SERCOM_ALT);
  pinPeripheral(3, PIO_SERCOM_ALT);

  // Start my new hardware serial
  mySerial.begin(4800);
pinMode(RE, OUTPUT);
  pinMode(DE, OUTPUT);
  
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); //initialize with the I2C addr 0x3C (128x64)
  delay(500);
  display.clearDisplay();
  display.setCursor(25, 15);
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.println(" NPK Sensor");
  display.setCursor(25, 35);
  display.setTextSize(1);
  display.print("Initializing");
  display.display();
  delay(3000);


}


 
void loop() {
  byte val1,val2,val3;
  val1 = nitrogen();
  delay(250);
  val2 = phosphorous();
  delay(250);
  val3 = potassium();
  delay(250);
  
  
  Serial.print("Nitrogen: ");
  Serial.print(val1);
  Serial.println(" mg/kg");
  Serial.print("Phosphorous: ");
  Serial.print(val2);
  Serial.println(" mg/kg");
  Serial.print("Potassium: ");
  Serial.print(val3);
  Serial.println(" mg/kg");
  delay(2000);
 
  display.clearDisplay();
  
 
  display.setTextSize(2);
  display.setCursor(0, 5);
  display.print("N: ");
  display.print(val1);
  display.setTextSize(1);
  display.print(" mg/kg");
 
  display.setTextSize(2);
  display.setCursor(0, 25);
  display.print("P: ");
  display.print(val2);
  display.setTextSize(1);
  display.print(" mg/kg");
 
  display.setTextSize(2);
  display.setCursor(0, 45);
  display.print("K: ");
  display.print(val3);
  display.setTextSize(1);
  display.print(" mg/kg");
 
  display.display();
}
 
byte nitrogen(){
  digitalWrite(DE,HIGH);
  digitalWrite(RE,HIGH);
  delay(10);
  if(mySerial.write(nitro,sizeof(nitro))==8){
    digitalWrite(DE,LOW);
    digitalWrite(RE,LOW);
    for(byte i=0;i<7;i++){
    //Serial.print(mod.read(),HEX);
    values[i] = mySerial.read();
    Serial.print(values[i],HEX);
    }
    Serial.println();
  }
  return values[4];
}
 
byte phosphorous(){
  digitalWrite(DE,HIGH);
  digitalWrite(RE,HIGH);
  delay(10);
  if(mySerial.write(phos,sizeof(phos))==8){
    digitalWrite(DE,LOW);
    digitalWrite(RE,LOW);
    for(byte i=0;i<7;i++){
    //Serial.print(mod.read(),HEX);
    values[i] = mySerial.read();
    Serial.print(values[i],HEX);
    }
    Serial.println();
  }
  return values[4];
}
 
byte potassium(){
  digitalWrite(DE,HIGH);
  digitalWrite(RE,HIGH);
  delay(10);
  if(mySerial.write(pota,sizeof(pota))==8){
    digitalWrite(DE,LOW);
    digitalWrite(RE,LOW);
    for(byte i=0;i<7;i++){
    //Serial.print(mod.read(),HEX);
    values[i] = mySerial.read();
    Serial.print(values[i],HEX);
    }
    Serial.println();
  }
  return values[4];
}
  

[gilshultz]

I cannot read your screen shot, check the forum guidelines. Also explain what your expecting and what you are or not getting in relationship to your expectations.

[UKHeliBob]

byte values[1];

A global array that can only hold 1 value

But later in the sketch you try to save several values to it

    for (byte i = 0; i < 7; i++)
    {
      //Serial.print(mod.read(),HEX);
      values[i] = mySerial.read();
      Serial.print(values[i], HEX);
    }

Then add insult to injury by returning one of those values