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