USART does not work

[DarkRabbit19]

Hi, can someone help me I'm using AVR studio 7 and when I compile the SerialLoopback code I get the folowing error's:

 Description                                                                    File                   Line
 #error "F_CPU must be a constant value"                                   setbaud.h                    121
 #error "setboud.h requires F_CPU to be defined"                        setbaud.h                    113
 #warning "UBRR value overflow" [-Wcpp]                                   setbaud.h                     235
 #'F_CPU' undeclared (first use in this function)                          USART.c                       24

the code I use is:

/*

• serialLoopback.c *
• Created: 31-1-2016 11:28:35
• Author : Dark A simple test of serial-port functionality. Takes in a character at a time and sends it right back out, displaying the ASCII value on the LEDs. */

  define F_CPU 100000 UL

// ------- Preamble -------- //

include <avr/io.h>

include <util/delay.h>

include "lib/pinDefines.h"

include "lib/USART.h"

int main(void) { char serialCharacter; // -------- Inits --------- // LEDDDR = 0xff; /* set up LEDs for output / initUSART(); printString("Hello World!\r\n"); / to test / // ------ Event loop ------ // while (1) { serialCharacter = receiveByte(); transmitByte(serialCharacter); LEDPORT = serialCharacter; / display ascii/numeric value of character / } / End event loop */ return (0); }

thanks in advance

[hessa59]

I seems like you have your CPU set at 0.1 MHZ ie #define F_CPU 100000 UL. Is this what you want?

Also I find this error #error "setboud.h requires F_CPU to be defined" to be strange. Shouldn't it be setbaud.h

[hexagon5un]

Hi!

Hessa59 is right -- you need to up your F_CPU define by a factor of ten. That's an easy typo to fix.

The other possible gotcha with Studio is that you might also need to set a BAUD define as well.

It has a way to set global compile-time defines like this. I can't remember off the top of my head what it is.

[DarkRabbit19]

I tried to do that but it dit not work. the libery does not work wit Atmel studio in general. in the and i made my own libery. (dropbox link: https://www.dropbox.com/sh/8ncnrjdd973qy6i/AAAOIanbFtVdW1teYvIutOmOa?dl=0) the only thing I am wondering is what you use instead of Atmelstudio.

[xavicci]

@DarkRabbit19 hola si funciona en atmelstudio7, agrega #define F_CPU 1000000 dentro de USART.c y escribe bien la palabra setbaud.h . http://es.tinypic.com/view.php?pic=ipzlmx&s=9#.VvvvwVXhCM8 mira la siguiente imagen, espero que te ayude!

[hexagon5un]

@Xavicci @DarkRabbit19

Another issue goes over problems with Studio: https://github.com/hexagon5un/AVR-Programming/issues/10

The BAUD, F_CPU problem is solvable like so: According to this website, Studio calls them "symbols" and they're found buried pretty deep in some menus: Project - Properties - Toolchain - All Configurations - Symbols.

But the truth is, I didn't intend to get into Studio -- they change it so often that anything I write about using the GUI will be wrong in a year. The stock compile is with any avr-gcc toolchain. See the book for more details? Or LadyAda has a good tutorial.

[DarkRabbit19]

In the end I made a other libery that works. thank you voor your time and the gread book

[hexagon5un]

Glad you like the book, and I'm sorry about the Studio woes. I wish I could keep up with them too, but they're a moving target.