qpc/examples/arm-cm/dpp_nucleo-l152re/qv/arm

About this Example
==================
This example demonstrates how to use the uVision IDE together with
the MDK-ARM toolchain.

***
NOTE: This example requires installing the following Software Pack
in the Keil uVision: Keil::STM32L152_DFP.
***


uVision Project File
====================
The MDK-ARM uVision project file provided with this example uses
relative paths to the QP/C framework location (includes, port, and
libraries. These relative paths must be modified when the project
is moved to different relative location.


Adjusting Stack and Heap Sizes
==============================
The stack and heap sizes are determined in this project by the 
command-line options for the ARM assembler (see the Asm tab in
the "Options for Target" dialog box in uVision). Specifically,
you should define symbols: Stack_Size=xxx Heap_Size=yyy, where
xxx represents a numerical value of stack size and yyy the
numberical value of the heap size (for most embedded projects
yyy should be 0, as the using the heap is not recommended).
   

Startup Code
============
The startup code for the STM32L1xx MCU used in this project is
located in the "3rd_party" folder in the following location:

3rd_party\nucleo-l152re\arm\startup_stm32l1xx.s

The file startup_stm32l1xx.s provides a template of the recommended
startup for QP applications and should be easily customizable for other
ARM Cortex-M microcontrollers.

The startup file typically does not need to be modified or adapted for
applications. It provides only weak definitions of all exception and
interrupt handlers, as well as the assert_failed() function.  

The weak function assert_failed() defined in this file might be re-defined
in the application to customize it for the application-specific error-
handling policy.

***
NOTE: The function assert_failed() typically should NOT use the stack,
because stack might be corrupted by the time this function is called.
Also, assert_failed() is intended to handle catastrophic errors and
should NOT return.
***
  
Adjusting the CPU Clock Speed
-----------------------------
The current setting is to run at 32MHz from the PLL, but the CPU clock
speed can be modified by editing the file system_stm32l1xx.c.

***
NOTE:
With the default setting of 8MHz external clock (HSE_VALUE=8000000), the
SystemCoreClockUpdate() routine in system_stm32l1xx.c sets the
SystemCoreClock variable to 32000000 (32MHz). However, the NUCLEO-L152RE
board appears to run actually only at 16MHz. As a quick fix, the
projects in the qpc\examples directory set the HSE_VALUE to only 4MHz
(HSE_VALUE=4000000) in the command-line options to the compiler, to match
the reporeted SystemCoreClock to the actual speed of the clock (16MHz).
At this point it is not clear why the CPU clock is set to only half of the
expected speed.
***