/******************** (C) COPYRIGHT 2003 STMicroelectronics ******************** | |
* File Name : WDG.c | |
* Author : MCD Application Team | |
* Date First Issued : 10/24/2003 | |
* Description : This file provides all the WDG software functions | |
******************************************************************************** | |
* History: | |
* 30/11/2004 : V2.0 | |
* 14/07/2004 : V1.3 | |
* 01/01/2004 : V1.2 | |
******************************************************************************* | |
THE PRESENT SOFTWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS WITH | |
CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME. | |
AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT, INDIRECT | |
OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE CONTENT | |
OF SUCH SOFTWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING INFORMATION | |
CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS. | |
*******************************************************************************/ | |
#include "wdg.h" | |
#ifndef abs | |
#define abs(x) ((x)>0 ? (x) : -(x)) | |
#endif | |
/******************************************************************************* | |
* Function Name : FindFactors | |
* Description : Search for the best (a,b) values that fit n = a*b | |
* with the following constraints: 1<=a<=256, 1<=b<=65536 | |
* Input 1 : n: the number to decompose | |
* Input/Output 2 : a: a pointer to the first factor | |
* Input/Output 3 : b: a pointer to the second factor | |
* Return : None | |
*******************************************************************************/ | |
static void FindFactors(unsigned long n, unsigned int *a, unsigned long *b) | |
{ | |
unsigned long b0; | |
unsigned int a0; | |
long err, err_min=n; | |
*a = a0 = ((n-1)/65536ul) + 1; | |
*b = b0 = n / *a; | |
for (; *a <= 256; (*a)++) | |
{ | |
*b = n / *a; | |
err = (long)*a * (long)*b - (long)n; | |
if (abs(err) > (*a / 2)) | |
{ | |
(*b)++; | |
err = (long)*a * (long)*b - (long)n; | |
} | |
if (abs(err) < abs(err_min)) | |
{ | |
err_min = err; | |
a0 = *a; | |
b0 = *b; | |
if (err == 0) break; | |
} | |
} | |
*a = a0; | |
*b = b0; | |
} | |
/******************************************************************************* | |
* Function Name : WDG_PeriodValueConfig | |
* Description : Set the prescaler and counter reload value | |
* Input : Amount of time (us) needed | |
* Return : None | |
*******************************************************************************/ | |
void WDG_PeriodValueConfig ( u32 Time ) | |
{ | |
unsigned int a; | |
unsigned long n, b; | |
n = Time * (RCCU_FrequencyValue(RCCU_PCLK) / 1000000); | |
FindFactors(n, &a, &b); | |
WDG->PR = a - 1; | |
WDG->VR = b - 1; | |
} | |
/******************* (C) COPYRIGHT 2003 STMicroelectronics *****END OF FILE****/ |