openGLCD and the F_CPU error

I don’t know where i should modify the F_CPU value knowing that i’m using the openGLCD library for my project.I tried to modify it in the sketch but i doesn’t seem to work.Can anyone help me with this, please!! :confused:

Don’t post screenshots of text! That is very unhelpful. When you encounter an error you’ll see a button on the right side of the orange bar “Copy error messages”. Click that button. Paste the error in a message here USING CODE TAGS (</> button on the toolbar). It is almost never appropriate to post screenshots but in some cases it is helpful to post images. You should attach and embed the image following these instructions:

What made you think you need to modify the F_CPU value? If you read it somewhere then post a link. Please use the chain links icon on the toolbar to make the URL clickable when you post links.

F_CPU is completely independent of openGLCD.
The openGLCD library code does look at F_CPU to be able to accurately determine low level h/w delays.
Lots of other Arduino code, including arduino core code, looks at and uses the F_CPU value.
F_CPU is set by the board type selected before you build the sketch. It cannot be set inside a sketch.
If you have a custom board/chip that uses a frequency that is different from any existing board type, then you will have to create your own board type in the boards.txt file to be able to specify this.

You will need to google around to find the information on how to do that.

— bill

Thank you Bill.