Hi,

Sorry for the rather vague issue, but I am having some problems getting your library to work with AtmelStudio 7 and Atmega328.
Even a clean project with the example multiple usart.c, and the required headers fails with multiple undeclared warnings. Explicitly defining the prototypes just digs me deeper down a rabbit hole with subsequent errors.
Is this a known incompatibility?

Regards,

Petter.

While I strongly believe my issue is in my build environment I am able to compile when I change the -mmcu to atmega328p. The atmega32u4 does not have UBBR or UBBR0 it only has UBRR1 and that might be causing the issue. However I do see the 32u4 in the header.

pio run -v
Processing atmega32u4 (platform: atmelavr; board_build.mcu: atmega32u4; board_build.f_cpu: 16000000L; upload_protocol: arduino; upload_speed: 115200; build_unflags: -std=gnu11; build_flags: -std=gnu99)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------HARDWARE: ATMEGA32U4 16MHz,
PACKAGES: 
 - toolchain-atmelavr 1.70300.191015 (7.3.0)
LDF: Library Dependency Finder -> http://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 4 compatible libraries
More details about "Library Compatibility Mode": https://docs.platformio.org/page/librarymanager/ldf.html#ldf-compat-mode
Scanning dependencies...
Dependency Graph
|-- <usart> (D:\Documents\OneDrive\Documents\PlatformIO\Projects\delme\lib\usart)
Building in release mode
avr-gcc -o .pio\build\atmega32u4\src\main.o -c -fno-fat-lto-objects -std=gnu99 -Os -Wall -ffunction-sections -fdata-sections -flto -mmcu=atmega32u4 -DF_CPU=16000000L -DPLATFORMIO=50101 -Iinclude -Isrc -Ilib\usart src\main.c
avr-gcc -o .pio\build\atmega32u4\libbd1\usart\usart.o -c -fno-fat-lto-objects -std=gnu99 -Os -Wall -ffunction-sections -fdata-sections -flto -mmcu=atmega32u4 -DF_CPU=16000000L -DPLATFORMIO=50101 -Ilib\usart lib\usart\usart.c
In file included from src\main.c:8:0:
lib\usart/usart.h:1439:7: warning: always_inline function might not be inlinable [-Wattributes]
  void uart1_hardware_flow_control_init(uint8_t ctsenable, uint8_t rtsenable) // pass true to enable
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from lib\usart\usart.c:18:0:
lib\usart\usart.h:1439:7: warning: always_inline function might not be inlinable [-Wattributes]
  void uart1_hardware_flow_control_init(uint8_t ctsenable, uint8_t rtsenable) // pass true to enable
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
avr-gcc-ar rc .pio\build\atmega32u4\libbd1\libusart.a .pio\build\atmega32u4\libbd1\usart\usart.o
avr-gcc -o .pio\build\atmega32u4\firmware.elf -Os -mmcu=atmega32u4 -Wl,--gc-sections -flto -fuse-linker-plugin .pio\build\atmega32u4\src\main.o -L.pio\build\atmega32u4 -Wl,--start-group .pio\build\atmega32u4\libbd1\libusart.a -lm -Wl,--end-group
usart.o (symbol from plugin): In function `uart1_hardware_flow_control_init':
(.text+0x0): multiple definition of `uart1_hardware_flow_control_init'
.pio\build\atmega32u4\src\main.o (symbol from plugin):(.text+0x0): first defined here
collect2.exe: error: ld returned 1 exit status
*** [.pio\build\atmega32u4\firmware.elf] Error 1
================================================================================================== [FAILED] Took 1.66 seconds ==================================================================================================

and the main.c file

#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <stdio.h>
#include <string.h>

#include "usart.h"


int main (void) {


  DDRB = 1 << 5;

  sei();
  uart1_init(BAUD_CALC(115200));
  uart1_putc('c');

  while (1) {
    _delay_ms(500);
    PORTB ^= 1 << 5;
  }

  return 0;
}

I get a warning emitted about incompatible types withe an alias.

$ avr-gcc -c -mmcu=atmega328p -DF_CPU=16000000 -O -o usart.o usart.c
usart.c:480:14: warning: 'uart0_putc_' alias between functions of incompatible types char(char)' and 'void(char)' [-Wattribute-alias=]
480 | char uart0_putc_(char data) attribute ((alias ("uart0_putc"))); // alias for uart_putc that returns passed argument unaffected by omitting any existent rule
| ^~~~~~~~~~~
usart.c:315:14: note: aliased declaration here
315 | void uart0_putc(char data)
| ^~~~~~~~~~

I'm not sure if this is due to something missing on my part.

make[1]: Entering directory '/home/paul/Cprojects/Production/Encoder2/MicrocontrollerCode/AVR/Src_Modules/MicroC_Application'

avr-gcc -Wall -Os -DF_CPU=8000000 -mmcu=atmega328p -std=c11 -Wall -D RELEASE -c src/example.c -o ../../Objects/ReleaseAvrStatic/example.o
In file included from src/example.c:8:0:
src/usart.h:1593:27: warning: type defaults to ‘int’ in declaration of ‘__flash’
void uart0_puts_p(const __flash char *string); // send string from flash memory
^
src/usart.h:1593:35: error: expected ‘;’, ‘,’ or ‘)’ before ‘char’
void uart0_puts_p(const __flash char *string); // send string from flash memory
^
src/example.c:12:6: warning: return type of ‘main’ is not ‘int’ [-Wmain]
void main(void)
^
src/example.c: In function ‘main’:
src/example.c:24:2: warning: implicit declaration of function ‘uart0_puts_p’ [-Wimplicit-function-declaration]
uart_puts_P("hello from flashed, usart\r\n"); // write string to usart buffer from flash memory // string is parsed by PSTR() macro
^
Makefile:25: recipe for target '../../Objects/ReleaseAvrStatic/example.o' failed
make[1]: *** [../../Objects/ReleaseAvrStatic/example.o] Error 1
make[1]: Leaving directory '/home/paul/Cprojects/Production/Encoder2/MicrocontrollerCode/AVR/Src_Modules/MicroC_Application'
Makefile:28: recipe for target 'Application' failed
make: *** [Application] Error 2

I think it is self explicative

getting below compile error while using in platformio

Linking .pio/build/ATmega328P/firmware.elf
/tmp/ccdNSK77.ltrans0.ltrans.o: In function load_loop_2065': <artificial>:(.text.startup+0x3a): relocation truncated to fit: R_AVR_13_PCREL against no symbol'
collect2: error: ld returned 1 exit status
*** [.pio/build/ATmega328P/firmware.elf] Error 1

Hello and first of all congratulations on an excellent library.
I have been using it for RS-232 and it works flawlessly.
I am now trying to use t with RS-485 features on on an ATtiny841 and I am getting a lot of build errors.
Most of them are
lvalue required as left operand of assignment wherever a call to ___PORT or ___DDR is done
I am also getting some
pasting "PORT" and "(" does not give a valid preprocessing token.
My configuration for RS-485 is the following:
#define RS485_CONTROL0_IOPORTNAME A #define RS485_CONTROL0_PIN 1
Once again thanks a lot for your great library

hey
thanks for lib
is usart synchronous mode is implemented?
i wanted to use slave sync mode, where UCSR1C=(1<<UMSEL1) and baud rate is = 0
is this possible?

Please consider adding support for tinyAVR 2-family, e.g., ATtiny424, ATtiny426, ATtiny427, ATtiny824, ATtiny826, ATtiny827, ATtiny1624, ATtiny1626, ATtiny1627, ATtiny3224, ATtiny3226, ATtiny3227.

Hi - a little advice - you have a lot od #define in code. for example:

void uart0_reinit(uint16_t ubrr_value)
{
	#ifdef USART0_USE_SOFT_RTS
		RTS0_PORT |= (1<<RTS0_IONUM);
	#endif
		
	#ifdef USART0_RS485_MODE
		RS485_CONTROL0_PORT &= ~(1<<RS485_CONTROL0_IONUM); //set low
		RS485_CONTROL0_DDR |= (1<<RS485_CONTROL0_IONUM);
	#endif
		
          // rest of the function
}

you can simply hide #defines by implement static functions:

static void USART0_USE_SOFT_RTS_func(void)
{
	#ifdef USART0_USE_SOFT_RTS
		RTS0_PORT |= (1<<RTS0_IONUM);
	#endif
}
static void USART0_RS485_MODE_on(void)
{
	#ifdef USART0_RS485_MODE
		RS485_CONTROL0_PORT &= ~(1<<RS485_CONTROL0_IONUM); //set low
		RS485_CONTROL0_DDR |= (1<<RS485_CONTROL0_IONUM);
	#endif
}

void uart0_reinit(uint16_t ubrr_value)
{
                USART0_USE_SOFT_RTS_func();
		USART0_RS485_MODE_on();
		
                // rest of the function
}
}

compiler will remove all unused jumps etc - and functions are easier to read. Of course- just in my opinion.

When I try to compile an example I have an error at those strings:

		fprintf(uart1_io, "Say my name: ");
		fscanf(uart1_io, "%s", buffer);
		fprintf(uart1_io, "So it's %s, You are damn' right.\n", buffer);

Error - incompatible type for argument 1 of 'fprintf'.

I use Atmel Studio 7 (Version: 7.0.2397 - )

Great library, good work! I tried the NO_USART0 option and generated a couple of errors, reckon the below changes might be the fix...
Line 1622 of usart.h;
shouldn't this be
UCSR3A_REGISTER |= (1<<U2X3_BIT);
instead of
UCSR3A_REGISTER |= (1<<U2X0_BIT);
?

Also, shouldn't line 5439 of usart.c be
[UDR_reg_IO] "M" (_SFR_IO_ADDR(UDR1_REGISTER)),
instead of of
[UDR_reg_IO] "M" (_SFR_IO_ADDR(UDR0_REGISTER)),
?
Hope this is constructive, haven't githubbed before :)

When setting RX_NEWLINE_MODE to anything other than "2", the following error occurs:
usart.o: In function uart0_getlnToFirstWhiteSpace': usart.c:2132: undefined reference to load_NULL_834'

It appears that the definition of the symbol "load_NULL_..." no longer exists in the assembly code.

Hi,
upon connecting the RX wire sometimes my ATmega324 hangs somewhere in the RX interrupt handler (found this out with debug LEDs, as I can't use JTAG). I don't know how to proceed further when looking for the error, as I have no clue about assembler.

I have excluded ground loop issues and tried various config options with no success.

Is there any config switch to make the whole thing more robust? A system freeze upon UART cable connection is unfortunately something I can't live with.

Thanks in advance!