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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [CORTEX_AT91SAM3U256_IAR/] [AT91Lib/] [peripherals/] [tc/] [tc.c] - Rev 595
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/* ---------------------------------------------------------------------------- * ATMEL Microcontroller Software Support * ---------------------------------------------------------------------------- * Copyright (c) 2008, 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. * ---------------------------------------------------------------------------- */ //------------------------------------------------------------------------------ // Headers //------------------------------------------------------------------------------ #include "tc.h" //------------------------------------------------------------------------------ // Global Functions //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ /// 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 an AT91S_TC instance. /// \param mode Operating mode (TC_CMR value). //------------------------------------------------------------------------------ void TC_Configure(AT91S_TC *pTc, unsigned int mode) { // Disable TC clock pTc->TC_CCR = AT91C_TC_CLKDIS; // Disable interrupts pTc->TC_IDR = 0xFFFFFFFF; // Clear status register pTc->TC_SR; // Set mode pTc->TC_CMR = mode; } //------------------------------------------------------------------------------ /// Enables the timer clock and performs a software reset to start the counting. /// \param pTc Pointer to an AT91S_TC instance. //------------------------------------------------------------------------------ void TC_Start(AT91S_TC *pTc) { pTc->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG; } //------------------------------------------------------------------------------ /// Disables the timer clock, stopping the counting. /// \param pTc Pointer to an AT91S_TC instance. //------------------------------------------------------------------------------ void TC_Stop(AT91S_TC *pTc) { pTc->TC_CCR = AT91C_TC_CLKDIS; } //------------------------------------------------------------------------------ /// Finds the best MCK divisor given the timer frequency and MCK. The result /// is guaranteed to satisfy the following equation: /// \pre /// (MCK / (DIV * 65536)) <= freq <= (MCK / DIV) /// \endpre /// with DIV being the highest possible value. /// \param freq Desired timer frequency. /// \param mck Master clock frequency. /// \param div Divisor value. /// \param tcclks TCCLKS field value for divisor. /// \return 1 if a proper divisor has been found; otherwise 0. //------------------------------------------------------------------------------ unsigned char TC_FindMckDivisor( unsigned int freq, unsigned int mck, unsigned int *div, unsigned int *tcclks) { const unsigned int divisors[5] = {2, 8, 32, 128, #if defined(at91sam9260) || defined(at91sam9261) || defined(at91sam9263) \ || defined(at91sam9xe) || defined(at91sam9rl64) || defined(at91cap9) \ || defined(at91sam9m10) || defined(at91sam9m11) BOARD_MCK / 32768}; #else 1024}; #endif unsigned int index = 0; // Satisfy lower bound while (freq < ((mck / divisors[index]) / 65536)) { index++; // If no divisor can be found, return 0 if (index == 5) { return 0; } } // Try to maximise DIV while satisfying upper bound while (index < 4) { if (freq > (mck / divisors[index + 1])) { break; } index++; } // Store results if (div) { *div = divisors[index]; } if (tcclks) { *tcclks = index; } return 1; }
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