TM4C123GH6PM怎么用TIVA像dsp程序写入pwm发生器模块比较器的比较值

PWM模块可以直接配置周期和占空比，函数如下（pwm.c文件中）

//*****************************************************************************
//
//! Sets the period of a PWM generator.
//!
//! \param ui32Base is the base address of the PWM module.
//! \param ui32Gen is the PWM generator to be modified. This parameter must be
//! one of \b PWM_GEN_0, \b PWM_GEN_1, \b PWM_GEN_2, or \b PWM_GEN_3.
//! \param ui32Period specifies the period of PWM generator output, measured
//! in clock ticks.
//!
//! This function sets the period of the specified PWM generator block, where
//! the period of the generator block is defined as the number of PWM clock
//! ticks between pulses on the generator block zero signal.
//!
//! \note Any subsequent calls made to this function before an update occurs
//! cause the previous values to be overwritten.
//!
//! \return None.
//
//*****************************************************************************
void
PWMGenPeriodSet(uint32_t ui32Base, uint32_t ui32Gen,
uint32_t ui32Period)
{
//
// Check the arguments.
//
ASSERT((ui32Base == PWM0_BASE) || (ui32Base == PWM1_BASE));
ASSERT(_PWMGenValid(ui32Gen));

//
// Compute the generator's base address.
//
ui32Gen = PWM_GEN_BADDR(ui32Base, ui32Gen);

//
// Set the reload register based on the mode.
//
if(HWREG(ui32Gen + PWM_O_X_CTL) & PWM_X_CTL_MODE)
{
//
// In up/down count mode, set the reload register to half the requested
// period.
//
ASSERT((ui32Period / 2) < 65536);
HWREG(ui32Gen + PWM_O_X_LOAD) = ui32Period / 2;
}
else
{
//
// In down count mode, set the reload register to the requested period
// minus one.
//
ASSERT((ui32Period <= 65536) && (ui32Period != 0));
HWREG(ui32Gen + PWM_O_X_LOAD) = ui32Period - 1;
}
}

//*****************************************************************************
//
//! Sets the pulse width for the specified PWM output.
//!
//! \param ui32Base is the base address of the PWM module.
//! \param ui32PWMOut is the PWM output to modify. This parameter must be one
//! of \b PWM_OUT_0, \b PWM_OUT_1, \b PWM_OUT_2, \b PWM_OUT_3, \b PWM_OUT_4,
//! \b PWM_OUT_5, \b PWM_OUT_6, or \b PWM_OUT_7.
//! \param ui32Width specifies the width of the positive portion of the pulse.
//!
//! This function sets the pulse width for the specified PWM output, where the
//! pulse width is defined as the number of PWM clock ticks.
//!
//! \note Any subsequent calls made to this function before an update occurs
//! cause the previous values to be overwritten.
//!
//! \return None.
//
//*****************************************************************************
void
PWMPulseWidthSet(uint32_t ui32Base, uint32_t ui32PWMOut,
uint32_t ui32Width)
{
uint32_t ui32GenBase, ui32Reg;

//
// Check the arguments.
//
ASSERT((ui32Base == PWM0_BASE) || (ui32Base == PWM1_BASE));
ASSERT(_PWMOutValid(ui32PWMOut));

//
// Compute the generator's base address.
//
ui32GenBase = PWM_OUT_BADDR(ui32Base, ui32PWMOut);

//
// If the counter is in up/down count mode, divide the width by two.
//
if(HWREG(ui32GenBase + PWM_O_X_CTL) & PWM_X_CTL_MODE)
{
ui32Width /= 2;
}

//
// Get the period.
//
ui32Reg = HWREG(ui32GenBase + PWM_O_X_LOAD);

//
// Make sure the width is not too large.
//
ASSERT(ui32Width < ui32Reg);

//
// Compute the compare value.
//
ui32Reg = ui32Reg - ui32Width;

//
// Write to the appropriate registers.
//
if(PWM_IS_OUTPUT_ODD(ui32PWMOut))
{
HWREG(ui32GenBase + PWM_O_X_CMPB) = ui32Reg;
}
else
{
HWREG(ui32GenBase + PWM_O_X_CMPA) = ui32Reg;
}
}