| /* ---------------------------------------------------------------------------- |
| * 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 <assert.h> |
| |
| /*------------------------------------------------------------------------------ |
| * 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 ; |
| } |
| |