Error compiling for Arduino Nano 33 BLE with LiquidCrystal library

Question

I recently started coding in the Arduino IDE for the Arduino Nano 33 BLE I bought. When I choose the Nano 33 BLE as my board, I get the following Error:

Arduino: 1.8.11 (Windows 10), Board: "Arduino Nano 33 BLE"

In file included from C:\Users\Niels\Documents\Arduino\libraries\LiquidCrystal\src\LiquidCrystal.cpp:1:0:

C:\Users\Niels\Documents\Arduino\libraries\LiquidCrystal\src\LiquidCrystal.h:45:36: error: expected class-name before '{' token

 class LiquidCrystal : public Print {

                                    ^

C:\Users\Niels\Documents\Arduino\libraries\LiquidCrystal\src\LiquidCrystal.h:86:9: error: 'Print' has not been declared

   using Print::write;

         ^~~~~

exit status 1
Error compiling for board Arduino Nano 33 BLE.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

I do not get this error when compiling for a normal Arduino nano board. This is my code:

#include <Arduino_LSM9DS1.h>
#include <LiquidCrystal.h>
LiquidCrystal lcd(12,11,5,4,3,2);

//pins:
const int measurePin = 13, calibratePin = 14, xHighPin = 15, xLowPin = 16, yHighPin = 17, yLowPin = 18;

//constants:
const int interval = 10;
const float delta = 10;

//variables:
boolean measureSts = LOW, calibrateSts = LOW, xyOK = true;
int count = 0, timer = 0;
float measurements[100], current, x, y, z, xZero, yZero, zZero;


//programm:
void setup() {
  lcd.begin(16,2);

  pinMode(measurePin, INPUT);
  pinMode(calibratePin, INPUT);
  pinMode(xHighPin, OUTPUT);
  pinMode(xLowPin, OUTPUT);
  pinMode(yHighPin, OUTPUT);
  pinMode(yLowPin, OUTPUT);
}

void loop() {
  if ( IMU.accelerationAvailable() ) {
    IMU.readAcceleration(x, y, z);
    calibrate();
    checkXY();
    measure();
    current = z - zZero;
    printValues();
  }
  else lcd.print("--geen  sensor--");
}

void checkXY() {
  xyOK = true;
  if ( x < xZero - delta ) {
    xyOK = false;
    digitalWrite(xLowPin, HIGH);
    digitalWrite(xHighPin, LOW);
  }
  else if ( x > xZero + delta ) {
    xyOK = false;
    digitalWrite(xLowPin, LOW);
    digitalWrite(xHighPin, HIGH);
  }
  if ( y < yZero - delta ) {
    xyOK = false;
    digitalWrite(yLowPin, HIGH);
    digitalWrite(yHighPin, LOW);
  }
  else if ( y > yZero + delta ) {
    xyOK = false;
    digitalWrite(yLowPin, LOW);
    digitalWrite(yHighPin, HIGH);
  }
}

void measure(){
  if ( digitalRead(measurePin) == LOW && measureSts == HIGH && xyOK ) {
    measurements[count] = z - zZero;
    zZero = z;
    timer = interval;
    count++;
  }
  measureSts = digitalRead(measurePin);
}

void printValues() {
  if ( timer >= interval ) {
    lcd.clear();
    lcd.setCursor(0,0);
    lcd.print("Meting: " + String(measurements[count]) + (char)223);
    lcd.setCursor(0,1);
    lcd.print("Huidig: " + String(current) + (char)223);
    timer = 0;
  }
  timer++;
}

void calibrate() {
  if ( digitalRead(calibratePin) == LOW && calibrateSts == true ) {
    xZero = x;
    yZero = y;
    lcd.setCursor(0,3);
    lcd.print("kalibreren");
    lcd.setCursor(1,4);
    lcd.print("voltooid");
    digitalWrite(xHighPin, HIGH);
    digitalWrite(xLowPin, HIGH);
    digitalWrite(yHighPin, HIGH);
    digitalWrite(yLowPin, HIGH);
    delay(100);
    lcd.clear();
    digitalWrite(xHighPin, LOW);
    digitalWrite(xLowPin, LOW);
    digitalWrite(yHighPin, LOW);
    digitalWrite(yLowPin, LOW);
  }
  calibrateSts = digitalRead(calibratePin);
}

For context: I am trying to create an angle-measuring device using the built-in accelerometer and a 2x16 LCD.

I hope someone can help me fixing this. Thanks in advance.

-Niels

Answer 1

The Arduino core for Nano 33 BLE is based on Mbed and can be used in Mbed as library. To achieve this, the Arduino API classes in this core are put in a namespace arduino::. This causes problems for libraries which include individual includes of Arduino API historically copied into cores for different MCU architecture platforms. The Arduino.h file includes the API files in the right way so in this case replacing #include"Print.h" with #include <Arduino.h> in LiquidCrystal.h solves the compilation problem.