Hi, having issues getting the provided code to compile. Running Raspberry Bullseye lite on Pi Zero W.

Have followed instructions on page here:
https://wiki.dfrobot.com/RS485_Wind_Direction_Transmitter_SKU_SEN0482#target_7

When I run the gcc command to compile, I get the folowing error.

Any ideas on how to fix this? Thanks!

Tim

/usr/bin/ld: /tmp/cczf094m.o:(.bss+0x0): multiple definition of `fd'; /tmp/ccIlIgNn.o:(.bss+0x0): first defined here /usr/bin/ld: /tmp/ccIlIgNn.o: in function `main': main.c:(.text+0x50): undefined reference to `delay' /usr/bin/ld: main.c:(.text+0xbc): undefined reference to `delay' /usr/bin/ld: /tmp/cczf094m.o: in function `ModifyAddress': RS485_Wind_Direction_Transmitter.c:(.text+0x158): undefined reference to `millis' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x1b0): undefined reference to `millis' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x1c8): undefined reference to `millis' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x1f8): undefined reference to `millis' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x210): undefined reference to `serialDataAvail' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x224): undefined reference to `delay' /usr/bin/ld: /tmp/cczf094m.o: in function `Init': RS485_Wind_Direction_Transmitter.c:(.text+0x3b8): undefined reference to `serialOpen' /usr/bin/ld: /tmp/cczf094m.o: in function `readWindDirection': RS485_Wind_Direction_Transmitter.c:(.text+0x478): undefined reference to `millis' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x4c8): undefined reference to `millis' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x4ec): undefined reference to `millis' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x51c): undefined reference to `millis' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x534): undefined reference to `serialDataAvail' /usr/bin/ld: RS485_Wind_Direction_Transmitter.c:(.text+0x548): undefined reference to `delay'