/* ---------------------------------------------------------------------------- * ATMEL Microcontroller Software Support * ---------------------------------------------------------------------------- * Copyright (c) 2009, Atmel Corporation * * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * - Redistributions of source code must retain the above copyright notice, * this list of conditions and the disclaimer below. * * Atmel's name may not be used to endorse or promote products derived from * this software without specific prior written permission. * * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE * DISCLAIMED. IN NO EVENT SHALL ATMEL 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. * ---------------------------------------------------------------------------- */ /** * \file * * Implementation of Timer Counter (TC). * */ /*------------------------------------------------------------------------------ * Headers *------------------------------------------------------------------------------*/ #include "chip.h" #include /*------------------------------------------------------------------------------ * Global functions *------------------------------------------------------------------------------*/ /** * \brief Configures a Timer Counter Channel * * Configures a Timer Counter to operate in the given mode. Timer is stopped * after configuration and must be restarted with TC_Start(). All the * interrupts of the timer are also disabled. * * \param pTc Pointer to a Tc instance. * \param channel Channel number. * \param mode Operating mode (TC_CMR value). */ extern void TC_Configure( Tc *pTc, uint32_t dwChannel, uint32_t dwMode ) { TcChannel* pTcCh ; assert( dwChannel < (sizeof( pTc->TC_CHANNEL )/sizeof( pTc->TC_CHANNEL[0] )) ) ; pTcCh = pTc->TC_CHANNEL+dwChannel ; /* Disable TC clock */ pTcCh->TC_CCR = TC_CCR_CLKDIS ; /* Disable interrupts */ pTcCh->TC_IDR = 0xFFFFFFFF ; /* Clear status register */ pTcCh->TC_SR ; /* Set mode */ pTcCh->TC_CMR = dwMode ; } /** * \brief Reset and Start the TC Channel * * Enables the timer clock and performs a software reset to start the counting. * * \param pTc Pointer to a Tc instance. * \param dwChannel Channel number. */ extern void TC_Start( Tc *pTc, uint32_t dwChannel ) { TcChannel* pTcCh ; assert( dwChannel < (sizeof( pTc->TC_CHANNEL )/sizeof( pTc->TC_CHANNEL[0] )) ) ; pTcCh = pTc->TC_CHANNEL+dwChannel ; pTcCh->TC_CCR = TC_CCR_CLKEN | TC_CCR_SWTRG ; } /** * \brief Stop TC Channel * * Disables the timer clock, stopping the counting. * * \param pTc Pointer to a Tc instance. * \param dwChannel Channel number. */ extern void TC_Stop(Tc *pTc, uint32_t dwChannel ) { TcChannel* pTcCh ; assert( dwChannel < (sizeof( pTc->TC_CHANNEL )/sizeof( pTc->TC_CHANNEL[0] )) ) ; pTcCh = pTc->TC_CHANNEL+dwChannel ; pTcCh->TC_CCR = TC_CCR_CLKDIS ; } /** * \brief Find best MCK divisor * * Finds the best MCK divisor given the timer frequency and MCK. The result * is guaranteed to satisfy the following equation: * \code * (MCK / (DIV * 65536)) <= freq <= (MCK / DIV) * \endcode * with DIV being the highest possible value. * * \param dwFreq Desired timer frequency. * \param dwMCk Master clock frequency. * \param dwDiv Divisor value. * \param dwTcClks TCCLKS field value for divisor. * \param dwBoardMCK Board clock frequency. * * \return 1 if a proper divisor has been found, otherwise 0. */ extern uint32_t TC_FindMckDivisor( uint32_t dwFreq, uint32_t dwMCk, uint32_t *dwDiv, uint32_t *dwTcClks, uint32_t dwBoardMCK ) { const uint32_t adwDivisors[5] = { 2, 8, 32, 128, dwBoardMCK / 32768 } ; uint32_t dwIndex = 0 ; /* Satisfy lower bound */ while ( dwFreq < ((dwMCk / adwDivisors[dwIndex]) / 65536) ) { dwIndex++ ; /* If no divisor can be found, return 0 */ if ( dwIndex == (sizeof( adwDivisors )/sizeof( adwDivisors[0] )) ) { return 0 ; } } /* Try to maximize DIV while satisfying upper bound */ while ( dwIndex < 4 ) { if ( dwFreq > (dwMCk / adwDivisors[dwIndex + 1]) ) { break ; } dwIndex++ ; } /* Store results */ if ( dwDiv ) { *dwDiv = adwDivisors[dwIndex] ; } if ( dwTcClks ) { *dwTcClks = dwIndex ; } return 1 ; }