Implementation

AN2551

6/8

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Implementation

The guidelines given above could be implemented in “C” code or even in the assembly

startup file. The current application note provides a special assembly startup file "91x_init.s"

for EWARM, RVDK, RIDE and RVMDK tools chain which covers all these guidelines.

This start-up file configures the PLL@96 Mhz to be the default clock source. It offers also

the ability to select either the OSC clock or the RTC clock.

The zip file associated with this application note contains:

●

The STR91x firmware library v1.2 from ST (source and header files).

●

A standard template project program that compiles all library files and also all the user

modifiable files needed to create a new project:

–

91x_conf.h: The configuration header file with all peripherals defined by default.

–

91x_it.c: The source file containing the interrupt handlers (the function bodies are

empty in this template).

–

main.c: The main program body.

–

EWARM, RVDK, RIDE, RVMDK sub-directories for each toolchain and contains

the modified start-up file "91x_init.s"

When booting from bank1:

●

Use OSC as the default clock source.

●

If you want to run the CPU @ 66 MHz or higher, the PLL configuration can be done in

the application code (“C” code) instead of in the start-up assembly file.

●

The Flash wait state selection instructions must be executed from SRAM as it is not

possible to read while writing in the same bank.