Uart Circular buffer , Error while building using Nucleo 429zi Just did what is in the video in the link https://controllerstech.com/ring-buffer-using-head-and-tail-in-stm32/ The error is as shown in the details

[RKore.1]

arm-none-eabi-gcc -o "Uart_Ring_Buffer.elf" @"objects.list"  -mcpu=cortex-m4 -T"C:\Users\User\STM32CubeIDE\workspace_1.8.0\Uart_Ring_Buffer\STM32F429ZITX_FLASH.ld" --specs=nosys.specs -Wl,-Map="Uart_Ring_Buffer.map" -Wl,--gc-sections -static --specs=nano.specs -mfpu=fpv4-sp-d16 -mfloat-abi=hard -mthumb -Wl,--start-group -lc -lm -Wl,--end-group

c:\st\stm32cubeide_1.8.0\stm32cubeide\plugins\com.st.stm32cube.ide.mcu.externaltools.gnu-tools-for-stm32.10.3-2021.10.win32_1.0.0.202111181127\tools\arm-none-eabi\bin\ld.exe: ./Core/Src/main.o:C:/Users/User/STM32CubeIDE/workspace_1.8.0/Uart_Ring_Buffer/Debug/../Core/Src/main.c:50: multiple definition of `huart2'; ./Core/Src/UartRingbuffer.o:C:/Users/User/STM32CubeIDE/workspace_1.8.0/Uart_Ring_Buffer/Debug/../Core/Src/UartRingbuffer.c:15: first defined here

collect2.exe: error: ld returned 1 exit status

make: *** [makefile:64: Uart_Ring_Buffer.elf] Error 1

"make -j8 all" terminated with exit code 2. Build might be incomplete.

[Tesla DeLorean · Accepted solution]

Error says you defined a variable in two files. Need to not do that​.

Decide where you want it, and use extern elsewhere.​

[RKore.1]

After searching huart2 in my code as shown below , I use extern as you mention

Do you see any error (multiple definition of `huart2';) ?

[Tesla DeLorean]

Is it in an include file?

[TDK]

> multiple definition of `huart2';

> ./Core/Src/UartRingbuffer.o:C:/Users/User/STM32CubeIDE/workspace_1.8.0/Uart_Ring_Buffer/Debug/../Core/Src/UartRingbuffer.c:15: first defined here

The error indicates that you've defined huart2 in UartRingbuffer.c on line 15. It shouldn't be defined there. Use extern. Would be easier to spot the error if you attached the relevant files.

[RKore.1]

Thanks , Tesla & TDK

you are correct it was in UartRingBuffer.c