I'm new to Keil and was using the evaluation version to write small programs. Now, suddenly my startup files no longer build and I get the following message. I rebuilt everything but still no joy. Any idea of how I can recover?
assembling startup_stm32f407xx.s... RTE\Device\STM32F407VGTx\startup_stm32f407xx.s(191): error: A1163E: Unknown opcode R0, , expecting opcode or Macro compiling system_stm32f4xx.c... ".\Objects\GroupAssignment3.axf" - 1 Error(s), 0 Warning(s). Target not created.
Perhaps you could show the offending line in the source file the assembler is complaining about, helps to understand the issue.
Take a reference version of the startup.s you started with and merge back in changes you have made.