Resolving a linker error: undefined reference to static class members

Question

My code is Arduinoish. I turned on verbose compiling so I could verify that all the .o files are indeed getting passed to the linker correctly, and they are (linker command

Answer 1

Because the value _serial is static, it exists when an object isn't instantiated. This means that you must declare it in the code as

NewSoftSerial SerialServoControl::_serial(9, 8);
char SerialServoControl::_tx = 0;
char SerialServoControl::_rx = 0;

which has already been suggested.

If you then want to change it in the init function, you simply have to change your _serial = ... line to SerialServoControl::_serial = NewSoftSerial(tx, rx). Of course, this means you'll have to define a relevant constructor for the NewSoftSerial class.

Hope this helps.