MLX90640 Sketch not working

Juergen-05 · April 20, 2021, 10:17am

I want to use the MLX90640 infrared sensor, but when i compare this example from sparkfun:

but when i use the compiler i get this error in the MLX90640-I2C_Driver.cpp:

I2C_BUFFER_LENGTH’ was not declared in this scope !

I use arduino 1.8.4 but i have no idea whats wrong?

Example1_BasicReadings.ino (3.17 KB)

MLX90640_API.cpp (29.2 KB)

MLX90640_API.h (2.07 KB)

MLX90640_I2C_Driver.cpp (2.95 KB)

MLX90640_I2C_Driver.h (1.54 KB)

Koepel · July 18, 2018, 3:06am

Please update to the newest version. There are new features and bug fixes in every newer version.

When using the ESP32, there is I2C_BUFFER_LENGTH in Wire.h

github.com

espressif/arduino-esp32/blob/master/libraries/Wire/src/Wire.h

/*
  TwoWire.h - TWI/I2C library for Arduino & Wiring
  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

  Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
  Modified December 2014 by Ivan Grokhotkov (ivan@esp8266.com) - esp8266 support

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When using a basic Arduino board with ATmega microcontroller from the AVR family, there is BUFFER_LENGTH in Wire.h

github.com

arduino/ArduinoCore-avr/blob/master/libraries/Wire/src/Wire.h

/*
  TwoWire.h - TWI/I2C library for Arduino & Wiring
  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

  Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
  Modified 2020 by Greyson Christoforo (grey@christoforo.net) to implement timeouts

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The Sparkfun library is probably not compatible with every board. Can you fix that yourself ?
Perhaps you can put this in your sketch: #define I2C_BUFFER_LENGTH BUFFER_LENGTH before including the *.h files.

pylon · July 18, 2018, 3:36pm

That define is in MLX90640_I2C_Driver.h already:

#if defined(__AVR_ATmega328P__) || defined(__AVR_ATmega168__)

//I2C_BUFFER_LENGTH is defined in Wire.H
#define I2C_BUFFER_LENGTH BUFFER_LENGTH

If none of the specified platform matches, the value is set to 32. So an undefined value shouldn't happen except you installed things not correctly. Did you install the *.h and *.cpp file correctly to the library folder?

Juergen-05 · July 18, 2018, 5:03pm

The Sparkfun library is probably not compatible with every board. Can you fix that yourself ? Perhaps you can put this in your sketch: #define I2C_BUFFER_LENGTH BUFFER_LENGTH before including the *.h files.

Hello Koepel you make my day, that was it! Thank you

system · May 6, 2021, 10:22am