2.2 MCC Melody Implementation

Create a new MPLAB® X IDE project for AVR16EB32.

Open MCC from the toolbar (more information on installing the MCC plug-in can be found here).

In MCC Content Manager Wizard, select MCC Melody, then click Finish.

Click Project Resources, go to System, select CLKCTRL and disable the Prescaler enable button; Clock Select: PLL Oscillator; PLL Multiplication Factor: Multiply by 16; PLL Source Division: DIV4; Prescaler B division PDIVB: DIV4.

From the Device Resources, go to Drivers and Timer window, add the TCE module, then do the following configuration:

– Module Enable: Must be enabled by default. If not, toggle the button (it turns blue if enabled)

– Clock Selection: System clock (by default, the divider must be 1 - System clock)

– Waveform Generation Mode: Dual-Slope PWM mode with overflow on TOP and BOTTOM (DSBOTH)

– Requested Period[s]: 0.0001

– Duty Cycle 0 [%]: 20

– Duty Cycle 1 [%]: 40

– Duty Cycle 2 [%]: 60

– Duty Cycle 3 [%]: 80

– Waveform Output n : Check the boxes from the Enable column for Waveform Output 0, 1, 2, 3

– Duty Cycle High Resolution: Resolution increased by 4

– Scale mode: CMP values are scaled from Bottom, 0% DC

– Scaled Writing to registers: Fractional

– Amplitude Control Enable: Toggle the button (it turns blue if enabled)

– Amplitude Value: 1

In the Pin Grid View window - check if the TCE_WO[0-3] pins are locked as outputs on PORTA. When the boxes from Enable column from Waveform Output n are checked, the pins are also locked. To change the PORT, click on a pin from another PORT in Pin Grid View. Select the PIN5 of PORTD as an output, then toggle it to see the amplitude and compare values changes.

In the Project Resources window, click the Generate button so that MCC will generate all the specified drivers and configurations.

Edit the main.c file, as following:

Add in the include files section:


#include "mcc_generated_files/system/system.h"
#include <util/delay.h>

Add macro definitions:


/* Calculated values for Period, CMP, Amplitude and OFFSET registers */
#define DUTY_CYCLE_20_PERCENT             (0x1999)
#define DUTY_CYCLE_40_PERCENT             (0x3333)
#define DUTY_CYCLE_60_PERCENT             (0x4CCC)    
#define DUTY_CYCLE_80_PERCENT             (0x660C)
#define AMPLITUDE_MAX_DCY_50_PERCENT      (0x4000)
#define AMPLITUDE_MAX_DCY_75_PERCENT      (0x6000)
#define AMPLITUDE_MAX_DCY_100_PERCENT     (0x8000)
#define AMPLITUDE_MAX_DCY_150_PERCENT     (0xC000)

Add function:


void Amplitude_Value_Set(uint16_t value)
{
    /* Set the value of amplitude */
    TCE0_AmplitudeSet(value);
    
    /* Rewrite the values in CMPBUF registers so that the duty cycle get scaled according
     * to the new value of amplitude */
    TCE0_CompareAllChannelsBufferedSet(DUTY_CYCLE_20_PERCENT, DUTY_CYCLE_40_PERCENT, 
                                       DUTY_CYCLE_60_PERCENT, DUTY_CYCLE_80_PERCENT);
    
    /* Toggle PD5 pin to know when the value of amplitude has changed */
    IO_PD5_Toggle();
}

Edit the main function:

int main(void)
{
    SYSTEM_Initialize();

    while(1)
    {
        Amplitude_Value_Set(AMPLITUDE_MAX_DCY_50_PERCENT);
        _delay_ms(10);
        Amplitude_Value_Set(AMPLITUDE_MAX_DCY_75_PERCENT);
        _delay_ms(10);
        Amplitude_Value_Set(AMPLITUDE_MAX_DCY_100_PERCENT);
        _delay_ms(10);
        Amplitude_Value_Set(AMPLITUDE_MAX_DCY_150_PERCENT);
        _delay_ms(10);
    }    
}

Now, the project can be built and run from MPLAB X IDE. At run time, the scaling value for the compare registers modifies every 10 ms, and the range of the duty cycles will be modified accordingly.