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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [CORTEX_AT91SAM3U256_IAR/] [AT91Lib/] [peripherals/] [pwmc/] [pwmc.c] - Rev 604
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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 "pwmc.h" #include <board.h> #include <utility/assert.h> #include <utility/trace.h> //------------------------------------------------------------------------------ // Local functions //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ /// Finds a prescaler/divisor couple to generate the desired frequency from /// MCK. /// Returns the value to enter in PWMC_MR or 0 if the configuration cannot be /// met. /// \param frequency Desired frequency in Hz. /// \param mck Master clock frequency in Hz. //------------------------------------------------------------------------------ static unsigned short FindClockConfiguration( unsigned int frequency, unsigned int mck) { unsigned int divisors[11] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024}; unsigned char divisor = 0; unsigned int prescaler; SANITY_CHECK(frequency < mck); // Find prescaler and divisor values prescaler = (mck / divisors[divisor]) / frequency; while ((prescaler > 255) && (divisor < 11)) { divisor++; prescaler = (mck / divisors[divisor]) / frequency; } // Return result if (divisor < 11) { TRACE_DEBUG("Found divisor=%u and prescaler=%u for freq=%uHz\n\r", divisors[divisor], prescaler, frequency); return prescaler | (divisor << 8); } else { return 0; } } //------------------------------------------------------------------------------ // Global functions //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ /// Configures PWM a channel with the given parameters. /// The PWM controller must have been clocked in the PMC prior to calling this /// function. /// Beware: this function disables the channel. It waits until disable is effective. /// \param channel Channel number. /// \param prescaler Channel prescaler. /// \param alignment Channel alignment. /// \param polarity Channel polarity. //------------------------------------------------------------------------------ void PWMC_ConfigureChannel( unsigned char channel, unsigned int prescaler, unsigned int alignment, unsigned int polarity) { SANITY_CHECK(prescaler < AT91C_PWMC_CPRE_MCKB); SANITY_CHECK((alignment & ~AT91C_PWMC_CALG) == 0); SANITY_CHECK((polarity & ~AT91C_PWMC_CPOL) == 0); // Disable channel (effective at the end of the current period) if ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) != 0) { AT91C_BASE_PWMC->PWMC_DIS = 1 << channel; while ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) != 0); } // Configure channel AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR = prescaler | alignment | polarity; } //------------------------------------------------------------------------------ /// Configures PWM clocks A & B to run at the given frequencies. This function /// finds the best MCK divisor and prescaler values automatically. /// \param clka Desired clock A frequency (0 if not used). /// \param clkb Desired clock B frequency (0 if not used). /// \param mck Master clock frequency. //------------------------------------------------------------------------------ void PWMC_ConfigureClocks(unsigned int clka, unsigned int clkb, unsigned int mck) { unsigned int mode = 0; unsigned int result; // Clock A if (clka != 0) { result = FindClockConfiguration(clka, mck); ASSERT(result != 0, "-F- Could not generate the desired PWM frequency (%uHz)\n\r", clka); mode |= result; } // Clock B if (clkb != 0) { result = FindClockConfiguration(clkb, mck); ASSERT(result != 0, "-F- Could not generate the desired PWM frequency (%uHz)\n\r", clkb); mode |= (result << 16); } // Configure clocks TRACE_DEBUG("Setting PWMC_MR = 0x%08X\n\r", mode); AT91C_BASE_PWMC->PWMC_MR = mode; } //------------------------------------------------------------------------------ /// Sets the period value used by a PWM channel. This function writes directly /// to the CPRD register if the channel is disabled; otherwise, it uses the /// update register CUPD. /// \param channel Channel number. /// \param period Period value. //------------------------------------------------------------------------------ void PWMC_SetPeriod(unsigned char channel, unsigned short period) { // If channel is disabled, write to CPRD if ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) == 0) { AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CPRDR = period; } // Otherwise use update register else { AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR |= AT91C_PWMC_CPD; AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CUPDR = period; } } //------------------------------------------------------------------------------ /// Sets the duty cycle used by a PWM channel. This function writes directly to /// the CDTY register if the channel is disabled; otherwise it uses the /// update register CUPD. /// Note that the duty cycle must always be inferior or equal to the channel /// period. /// \param channel Channel number. /// \param duty Duty cycle value. //------------------------------------------------------------------------------ void PWMC_SetDutyCycle(unsigned char channel, unsigned short duty) { SANITY_CHECK(duty <= AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CPRDR); // SAM7S errata #if defined(at91sam7s16) || defined(at91sam7s161) || defined(at91sam7s32) \ || defined(at91sam7s321) || defined(at91sam7s64) || defined(at91sam7s128) \ || defined(at91sam7s256) || defined(at91sam7s512) ASSERT(duty > 0, "-F- Duty cycle value 0 is not permitted on SAM7S chips.\n\r"); ASSERT((duty > 1) || (AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR & AT91C_PWMC_CALG), "-F- Duty cycle value 1 is not permitted in left-aligned mode on SAM7S chips.\n\r"); #endif // If channel is disabled, write to CDTY if ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) == 0) { AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CDTYR = duty; } // Otherwise use update register else { AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR &= ~AT91C_PWMC_CPD; AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CUPDR = duty; } } //------------------------------------------------------------------------------ /// Enables the given PWM channel. This does NOT enable the corresponding pin; /// this must be done in the user code. /// \param channel Channel number. //------------------------------------------------------------------------------ void PWMC_EnableChannel(unsigned char channel) { AT91C_BASE_PWMC->PWMC_ENA = 1 << channel; } //------------------------------------------------------------------------------ /// Disables the given PWM channel. /// Beware, channel will be effectively disabled at the end of the current period. /// Application can check channel is disabled using the following wait loop: /// while ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) != 0); /// \param channel Channel number. //------------------------------------------------------------------------------ void PWMC_DisableChannel(unsigned char channel) { AT91C_BASE_PWMC->PWMC_DIS = 1 << channel; } //------------------------------------------------------------------------------ /// Enables the period interrupt for the given PWM channel. /// \param channel Channel number. //------------------------------------------------------------------------------ void PWMC_EnableChannelIt(unsigned char channel) { AT91C_BASE_PWMC->PWMC_IER = 1 << channel; } //------------------------------------------------------------------------------ /// Disables the period interrupt for the given PWM channel. /// \param channel Channel number. //------------------------------------------------------------------------------ void PWMC_DisableChannelIt(unsigned char channel) { AT91C_BASE_PWMC->PWMC_IDR = 1 << channel; }
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