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STR91x Software Library

STMicroelectronics provides an extensive software library for the STR9 device series. The library is ported to MDK-ARM and the ARM Compiler, and is available in the folder ...\ARM\RV31\LIB\ST.

The STR91x Software Library is a software collection for the STR9 peripherals. The library contains a set of functions for each peripheral. ST provides detailed documentation in the STR91x Software Library Users Manual which is available after installation on the µVision Project Workspace — Books tab.

The STR91x Software Library is available in two pre-built versions (source code is in a sub-folder):

  • STR91xD.LIB: (Debug Version) ST specific interrupt handling and debug variables for peripherals. Because the Keil µVision Debugger provides detailed outputs for all on-chip peripherals, this library is not required when you are using the Keil µVision Debugger.
  • STR91xR.LIB: (Release Version) ST specific interrupt handling without debug variables.


  • If you use this library for different hardware, you may need to change the settings in the 91x_conf.h file and re-build the library using the µVision project.
  • If you use any ST library functions, be sure to include the header file, 91x_lib.H, since it contains the definitions for the STR91x Software Library functions and macros.
  • The Keil RTX is compatible with the STR91x libraries.


Project Workspace When using the ST specific interrupt handling, you need to add a copy of the source file ...\ARM\EXAMPLES\ST\STR91x\MC\EXAMPLE1\91x_it.c to your project.


It is strongly recommended that you copy this file to your project folder.

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