contiki/cpu/pic32/lib/pic32_clock.c

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/*
* Contiki PIC32 Port project
*
* Copyright (c) 2012,
* Scuola Superiore Sant'Anna (http://www.sssup.it) and
* Consorzio Nazionale Interuniversitario per le Telecomunicazioni
* (http://www.cnit.it).
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/**
* \addtogroup pic32 PIC32 Contiki Port
*
* @{
*/
/**
* \file pic32_clock.c
* \brief CLOCK interface for PIC32MX (pic32mx795f512l)
* \author Giovanni Pellerano <giovanni.pellerano@evilaliv3.org>
* \date 2012-04-11
*/
/*
* PIC32MX795F512L - Specific Functions
*
* All the functions in this part of the file are specific for the
* pic32mx795f512l that is characterized by registers' name that differ from
* the 3xx and 4xx families of the pic32mx.
*/
#include <pic32_clock.h>
#include <p32xxxx.h>
#include <stdint.h>
#define CLOCK_SOURCE 8000000ul
#define DEVCFG2 0xBFC02FF4 /* virtual address of the register */
#define PLLIDIV_MASK 0x7
static const uint16_t FPPLIDIV[8] = { 1, 2, 3, 4, 5, 6, 10, 12 };
static const uint16_t PLLODIV[8] = { 1, 2, 4, 8, 16, 32, 64, 256 };
static const uint16_t PLLMULT[8] = { 15, 16, 17, 18, 19, 20, 21, 24 };
static const uint16_t PBDIV[4] = { 1, 2, 4, 8 };
/*---------------------------------------------------------------------------*/
/**
* \brief Calculate the system clock.
*
* \return the system clock value.
*/
uint32_t
pic32_clock_get_system_clock(void)
{
return CLOCK_SOURCE *
PLLMULT[(uint32_t) OSCCONbits.PLLMULT] /
(FPPLIDIV[(*((uint32_t *) DEVCFG2)) & PLLIDIV_MASK] *
PLLODIV[(uint32_t) OSCCONbits.PLLODIV]);
}
/*---------------------------------------------------------------------------*/
/**
* \brief Calculate the peripheral clock.
*
* \return the peripheral clock value.
*/
uint32_t
pic32_clock_get_peripheral_clock(void)
{
return pic32_clock_get_system_clock() / PBDIV[OSCCONbits.PBDIV];
}
/*---------------------------------------------------------------------------*/
uint32_t
pic32_clock_calculate_brg(uint32_t mul, uint32_t desired)
{
uint32_t fp = pic32_clock_get_peripheral_clock();
uint32_t brg[3];
uint32_t obtained[3];
int32_t err[3];
uint32_t min;
brg[0] = fp / (mul * desired); // +1
brg[1] = fp / (mul * desired) - 1; // 0
brg[2] = fp / (mul * desired) - 2; // -1
obtained[0] = fp / (mul * (brg[0] + 1));
obtained[1] = fp / (mul * (brg[1] + 1));
obtained[2] = fp / (mul * (brg[2] + 1));
err[0] = obtained[0] - desired;
err[1] = obtained[1] - desired;
err[2] = obtained[2] - desired;
err[0] = err[0] < 0 ? -err[0] : err[0];
err[1] = err[1] < 0 ? -err[1] : err[1];
err[2] = err[2] < 0 ? -err[2] : err[2];
min = 0;
min = err[1] < err[min] ? 1 : min;
min = err[2] < err[min] ? 2 : min;
return brg[min];
}
/** @} */