Mixing C and C++ (again): 'Serial' undeclared

Projects Programming
1

I'm returning to the Arduino world after developing a lot of dedicated embedded C code. And I'm immediately stumped on something simple. Here's the error message:

/var/folders/7x/bsz1mn9d5ps8pzs886s71d9m0000gq/T/arduino_build_250184/sketch/taos_test_support.c: In function 'taos_assert':
taos_test_support.c:8:5: error: 'Serial' undeclared (first use in this function)
     Serial.print(func);
     ^

Here's my sketch and supporting C file:

// file: taos_list_test.ino
#include "taos_test_support.h"

void setup() {
  Serial.begin(19200);
  Serial.println("hello...");
  TAOS_ASSERT(1 == 2);
}

void loop() {
}

// file: taos_test_support.h
#ifndef TAOS_TEST_SUPPORT_H
#define TAOS_TEST_SUPPORT_H

#include <stdbool.h>

#ifdef __cplusplus
extern "C" {
#endif

#define TAOS_ASSERT(expr) taos_assert((expr), __func__, __FILE__, __LINE__)

void taos_assert(const bool expr,
                 const char *const func,
                 const char *const file,
                 const int line);

#ifdef __cplusplus
}
#endif

#endif // #ifndef TAOS_TEST_SUPPORT_H

// file: taos_test_support.c
#include "taos_test_support.h"
// #include <Serial.h> -- see note

void taos_assert(const bool expr,
                 const char *const func,
                 const char *const file,
                 const int line) {
  if (!expr) {
    Serial.print(func);
    Serial.print(" failed:");
    Serial.print(file);
    Serial.print(":");
    Serial.print(line);
    Serial.println();
  }
}

Other info:

  • Arduino v 1.8.8 for MacOS
  • Board = Adafruit ItsyBitsy 32u4

It does not surprise me that Serial is undeclared. But I've not yet figured out how to include. On line 3 of taos_test_support.c, I've tried pretty much every combination I can think of:

#include <Serial.h>
#include <Serial>
#include "Serial.h"
#include <serial.h>
#include <serial>

... but those all result in "Serial: No such file or directory" or similar errors.

What am I missing?

2

You can use C code in C++, no problem, but you can't use C++ code in C. If you're using the Serial object, you're writing C++, not C. So use the correct file extension: taos_test_support.cpp

3

@pert:

Thanks.

I renamed taos_test_support.c to taos_test_support.cpp and added #include <Serial.h> at line two of the file. I'm now getting:

taos_test_support.cpp:2:20: error: Serial.h: No such file or directory

So, I'm clearly not understanding something from your answers. Can you elaborate?

4

There is no file named Serial.h. You can bring in the full Arduino standard core library API (including Serial) like this:

#include <Arduino.h>

If you only want the hardware serial functionality, I believe you can do this:

#include <HardwareSerial.h>
5

Many thanks. That worked.

6

You're welcome. I'm glad to hear it's working now. Enjoy!
Per