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Subversion Repositories openrisc_2011-10-31

[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [Common/] [drivers/] [Atmel/] [at91lib/] [peripherals/] [pwmc/] [pwmc.c] - Blame information for rev 608

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Line No. Rev Author Line
1 608 jeremybenn
/* ----------------------------------------------------------------------------
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 *         ATMEL Microcontroller Software Support
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 * ----------------------------------------------------------------------------
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 * Copyright (c) 2008, Atmel Corporation
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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 are met:
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 *
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 * - Redistributions of source code must retain the above copyright notice,
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 * this list of conditions and the disclaimer below.
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 *
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 * Atmel's name may not be used to endorse or promote products derived from
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 * this software without specific prior written permission.
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 *
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 * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
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 * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 * ----------------------------------------------------------------------------
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 */
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//------------------------------------------------------------------------------
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//         Headers
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//------------------------------------------------------------------------------
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#include "pwmc.h"
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#include <board.h>
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#include <utility/assert.h>
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#include <utility/trace.h>
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//------------------------------------------------------------------------------
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//         Local functions
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//------------------------------------------------------------------------------
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//------------------------------------------------------------------------------
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/// Finds a prescaler/divisor couple to generate the desired frequency from
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/// MCK.
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/// Returns the value to enter in PWMC_MR or 0 if the configuration cannot be
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/// met.
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/// \param frequency  Desired frequency in Hz.
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/// \param mck  Master clock frequency in Hz.
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//------------------------------------------------------------------------------
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static unsigned short FindClockConfiguration(
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    unsigned int frequency,
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    unsigned int mck)
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{
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    unsigned int divisors[11] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024};
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    unsigned char divisor = 0;
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    unsigned int prescaler;
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    SANITY_CHECK(frequency < mck);
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    // Find prescaler and divisor values
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    prescaler = (mck / divisors[divisor]) / frequency;
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    while ((prescaler > 255) && (divisor < 11)) {
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        divisor++;
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        prescaler = (mck / divisors[divisor]) / frequency;
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    }
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    // Return result
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    if (divisor < 11) {
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        trace_LOG(trace_DEBUG, "-D- Found divisor=%u and prescaler=%u for freq=%uHz\n\r",
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                  divisors[divisor], prescaler, frequency);
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        return prescaler | (divisor << 8);
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    }
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    else {
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        return 0;
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    }
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}
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//------------------------------------------------------------------------------
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//         Global functions
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//------------------------------------------------------------------------------
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//------------------------------------------------------------------------------
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/// Configures PWM a channel with the given parameters.
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/// The PWM controller must have been clocked in the PMC prior to calling this
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/// function.
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/// \param channel  Channel number.
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/// \param prescaler  Channel prescaler.
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/// \param alignment  Channel alignment.
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/// \param polarity  Channel polarity.
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//------------------------------------------------------------------------------
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void PWMC_ConfigureChannel(
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    unsigned char channel,
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    unsigned int prescaler,
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    unsigned int alignment,
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    unsigned int polarity)
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{
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    SANITY_CHECK(prescaler < AT91C_PWMC_CPRE_MCKB);
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    SANITY_CHECK((alignment & ~AT91C_PWMC_CALG) == 0);
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    SANITY_CHECK((polarity & ~AT91C_PWMC_CPOL) == 0);
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    // Disable channel
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    AT91C_BASE_PWMC->PWMC_DIS = 1 << channel;
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    // Configure channel
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    AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR = prescaler | alignment | polarity;
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}
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//------------------------------------------------------------------------------
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/// Configures PWM clocks A & B to run at the given frequencies. This function
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/// finds the best MCK divisor and prescaler values automatically.
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/// \param clka  Desired clock A frequency (0 if not used).
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/// \param clkb  Desired clock B frequency (0 if not used).
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/// \param mck  Master clock frequency.
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//------------------------------------------------------------------------------
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void PWMC_ConfigureClocks(unsigned int clka, unsigned int clkb, unsigned int mck)
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{
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    unsigned int mode = 0;
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    unsigned int result;
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    // Clock A
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    if (clka != 0) {
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        result = FindClockConfiguration(clka, mck);
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        ASSERT(result != 0, "-F- Could not generate the desired PWM frequency (%uHz)\n\r", clka);
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        mode |= result;
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    }
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    // Clock B
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    if (clkb != 0) {
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        result = FindClockConfiguration(clkb, mck);
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        ASSERT(result != 0, "-F- Could not generate the desired PWM frequency (%uHz)\n\r", clkb);
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        mode |= (result << 16);
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    }
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    // Configure clocks
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    trace_LOG(trace_DEBUG, "-D- Setting PWMC_MR = 0x%08X\n\r", mode);
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    AT91C_BASE_PWMC->PWMC_MR = mode;
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}
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//------------------------------------------------------------------------------
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/// Sets the period value used by a PWM channel. This function writes directly
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/// to the CPRD register if the channel is disabled; otherwise, it uses the
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/// update register CUPD.
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/// \param channel  Channel number.
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/// \param period  Period value.
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//------------------------------------------------------------------------------
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void PWMC_SetPeriod(unsigned char channel, unsigned short period)
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{
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    // If channel is disabled, write to CPRD
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    if ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) == 0) {
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        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CPRDR = period;
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    }
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    // Otherwise use update register
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    else {
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        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR |= AT91C_PWMC_CPD;
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        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CUPDR = period;
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    }
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}
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//------------------------------------------------------------------------------
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/// Sets the duty cycle used by a PWM channel. This function writes directly to
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/// the CDTY register if the channel is disabled; otherwise it uses the
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/// update register CUPD.
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/// Note that the duty cycle must always be inferior or equal to the channel
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/// period.
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/// \param channel  Channel number.
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/// \param duty  Duty cycle value.
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//------------------------------------------------------------------------------
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void PWMC_SetDutyCycle(unsigned char channel, unsigned short duty)
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{
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    SANITY_CHECK(duty <= AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CPRDR);
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    // SAM7S errata
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#if defined(at91sam7s16) || defined(at91sam7s161) || defined(at91sam7s32) \
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    || defined(at91sam7s321) || defined(at91sam7s64) || defined(at91sam7s128) \
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    || defined(at91sam7s256) || defined(at91sam7s512)
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    ASSERT(duty > 0, "-F- Duty cycle value 0 is not permitted on SAM7S chips.\n\r");
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    ASSERT((duty > 1) || (AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR & AT91C_PWMC_CALG),
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           "-F- Duty cycle value 1 is not permitted in left-aligned mode on SAM7S chips.\n\r");
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#endif
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    // If channel is disabled, write to CDTY
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    if ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) == 0) {
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        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CDTYR = duty;
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    }
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    // Otherwise use update register
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    else {
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        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR &= ~AT91C_PWMC_CPD;
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        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CUPDR = duty;
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    }
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}
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//------------------------------------------------------------------------------
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/// Enables the given PWM channel. This does NOT enable the corresponding pin;
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/// this must be done in the user code.
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/// \param channel  Channel number.
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//------------------------------------------------------------------------------
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void PWMC_EnableChannel(unsigned char channel)
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{
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    AT91C_BASE_PWMC->PWMC_ENA = 1 << channel;
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}
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//------------------------------------------------------------------------------
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/// Disables the given PWM channel.
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/// \param channel  Channel number.
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//------------------------------------------------------------------------------
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void PWMC_DisableChannel(unsigned char channel)
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{
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    AT91C_BASE_PWMC->PWMC_DIS = 1 << channel;
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}
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//------------------------------------------------------------------------------
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/// Enables the period interrupt for the given PWM channel.
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/// \param channel  Channel number.
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//------------------------------------------------------------------------------
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void PWMC_EnableChannelIt(unsigned char channel)
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{
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    AT91C_BASE_PWMC->PWMC_IER = 1 << channel;
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}
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//------------------------------------------------------------------------------
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/// Disables the period interrupt for the given PWM channel.
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/// \param channel  Channel number.
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//------------------------------------------------------------------------------
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void PWMC_DisableChannelIt(unsigned char channel)
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{
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    AT91C_BASE_PWMC->PWMC_IDR = 1 << channel;
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}
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