Troubleshooting Define Commands in C for Robot Motor Control

[Lancelot59]

This is once again for my robot. My current issue is with a define command:

I have the following function defined in motor_control.c:

//*****************************************************************************
//Motor Control Functions
//*****************************************************************************
void forward(void)			//Go striaght forward
{
	motorR(THROTTLE,TRIM);
	motorL(THROTTLE,TRIM);
}

The throttle value controls speed, trim offsets the speed variable. Although it probably will be eliminated.

Anyhow, I have throttle defined in a header called system_config.h:

#define THROTTLE = fast 	//Default forward throttle value to use

The value for "fast" has been enumerated in the header for motor_control.c

I have included the system_config.h file in the motor_control.c library, so what can't I see it? As far as I'm aware it should be able to see that defined value.

 

[magwas]

Show error messages.

 

[D H]

Get rid of the equals sign.

#define THROTTLE fast

 

[Lancelot59]

Get rid of the equals sign.

#define THROTTLE fast

...That was a silly mistake. Thanks for the catch.

The only error message I got was a syntax error when the compiler got to the first function that tried to pass THROTTLE to a function. It didn't say anything else.

Thanks again for the help.

 

[Mark44]

The code your compiler saw was this.

motorR(= fast,TRIM);
motorL(= fast,TRIM);

The reason for this is that the #define preprocessor directive does nothing more than text replacement. This is why you DON'T want to put = in simple preprocessor directives.

 

[Lancelot59]

I see, that makes sense.