File content as of revision 1:909f2393bc01:

#include "mbed.h"

#include "FullBridgeDriver.h"

FullBridgeDriver::FullBridgeDriver(void)
{
    // turn on power to PWM
    // on by default LPC_SC->PCONP |= (1<<6);
    isEnabled = false;
    
    // when the pins are used as GPIO - They should be outputs
    LPC_GPIO2->FIODIR |= (1<<4);
    LPC_GPIO2->FIODIR |= (1<<6);
    
    // and they should be low
    LPC_GPIO2->FIOCLR = (1<<4);
    LPC_GPIO2->FIOCLR = (1<<6);
    
    // enable PWM clock, set it to CCLK
    // set to CCLK/4 by default
    LPC_SC->PCLKSEL0 &= ~(3 << 12);
    LPC_SC->PCLKSEL0 |= (1 << 12);
    
    // PWM on
    LPC_SC->PCONP |= (1 << 6);
    
    // counter reset
    LPC_PWM1->TCR = 2;
    
    // we don't use the prescaler
    LPC_PWM1->PR = 0;
    
    // reset our counter on match of MR0
    LPC_PWM1->MCR = (1<<1);
    
    // enable PWM5 and PWM6, set both as double edged
    LPC_PWM1->PCR |= 0x5050;
    
    // set our starting frequency
    ChangeFrequency(DEFAULT_PWM_FREQUENCY);
    currentFrequency = DEFAULT_PWM_FREQUENCY;
    
    // counter enable, PWM enable
    LPC_PWM1->TCR = (1<<0) | (1<<3);
    
}

double FullBridgeDriver::GetActualFrequency(void)
{
    return (48.0 * 1000 / LPC_PWM1->MR5);
}

void FullBridgeDriver::SetState(double kHzFrequency)
{
    // update our frequency if requested
    if( kHzFrequency != currentFrequency )
    {
        // Set the frequency
        ChangeFrequency(kHzFrequency);
        currentFrequency = kHzFrequency;
    }
}

void FullBridgeDriver::Enable(bool enabled)
{
    // never mind if we're already in the correct state
    if (enabled == isEnabled)
        return;
    isEnabled = enabled;
        
    // this clears the bit fields for pin selection, which sets them as GPIO
    LPC_PINCON->PINSEL4 &=~(3<<6);            
    LPC_PINCON->PINSEL4 &=~(3<<10);           
    
    // GPIO is what we want if we are disabling
    if (!enabled)
        return;
    
    // else set the bit fields to indicate that our output pins are PWM outputs
    LPC_PINCON->PINSEL4 |= (1<<6);            
    LPC_PINCON->PINSEL4 |= (1<<10);           
    
}

void FullBridgeDriver::ChangeFrequency(double kHzFrequency)
{
    // calculate the timer period... we want the closest even number
    // so that we can get a 50% duty cycle
    double fTicks = 96000.0 / kHzFrequency;
    double fDoubleTicks = fTicks / 2;
    int doubleTicks = (int)(fDoubleTicks + 0.5);

    // things are set up like this:
    // PWM period: LPC_PWM1->MR0
    // pwm2:
    //     start counter: LPC_PWM1->MR3
    //     stop counter: LPC_PWM1->MR4
    // pwm1:
    //     start counter: LPC_PWM1->MR5
    //     stop counter: LPC_PWM1->MR6
    LPC_PWM1->MR0 = doubleTicks * 2;
    LPC_PWM1->MR3 = 5;      // set the pwm4 output high at this count
    LPC_PWM1->MR4 = doubleTicks - 6;      // set the pwm4 output low at this count
    LPC_PWM1->MR5 = doubleTicks;      // Set PWM6 output high at this count
    LPC_PWM1->MR6 = doubleTicks * 2;      // Set PWM6 output low at this count

    // enable PWM4 and PWM6, set both as double edge
    LPC_PWM1->PCR |= 0x5050;

    // this latches the values we set above into the shadow registers
    LPC_PWM1->LER |= 0x79;
      

}