qdec_signal_generator.h File Reference

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Functions
void	generate_qdec_signal (PORT_t *qPort, uint8_t lineCount, uint8_t freq, bool dir)
	Initializes TCE0 to create Qadrature signal. More...

Function Documentation

generate_qdec_signal()

void generate_qdec_signal	(	PORT_t *	qPort,
		uint8_t	lineCount,
		uint8_t	freq,
		bool	dir
	)

Initializes TCE0 to create Qadrature signal.

Calculates the values to create a Quadrature signal that has a frequency given from the freq parameter.

Parameters

qPort	The port to set the signal out on.
lineCount	The number of lines in the Quadrature encoder.
freq	The frequency that is put out, (time between index signal/one rotation).
dir	The direction of the signal to be generated, clockwise or counterclockwise signal.

Definition at line 94 of file qdec_signal_generator.c.

References F_CPU, lineCount, q_test_sig_Port, and test_lineCount.

Referenced by main().

{
        uint16_t ticks, quarter, half_quarter;

        /* The following code calculates the upper boundary of the timer and the
         * interrupt positions to get a correct Quadrature signal of the given frequency.
         *
         * The different compare interrupts sets the phase0 and phase90 signals.
         * Compare A interrupt sets phase0 and clears phase90
         * Compare B interrupt sets phase0 and phase90
         * Compare C interrupt clears phase0 and sets phase90
         * Compare D interrupt clears phase0 and phase90.
         *
         * Compare A interrupt also sets the index signal when one round has passed.
         */

        /* Calculates upper boundary of timer to get desired frequency.*/
        ticks = F_CPU / (freq * lineCount);
        quarter = ticks/4;
        half_quarter = ticks/8;

        if(dir == 1){
                TCE0.CCA = half_quarter;
                TCE0.CCB = half_quarter+quarter;
                TCE0.CCC = half_quarter+(2*quarter);
                TCE0.CCD = half_quarter+(3*quarter);
        }else{
                TCE0.CCA = half_quarter+(3*quarter);
                TCE0.CCB = half_quarter+(2*quarter);
                TCE0.CCC = half_quarter+quarter;
                TCE0.CCD = half_quarter;
        }

        TCE0.PER = ticks;
        TCE0.CTRLA = TC_CLKSEL_DIV1_gc;

        /* Enable low level interrupt on CCA, CCB, CCC and CCD.*/
        TCE0.INTCTRLB = TC0_CCAINTLVL0_bm | TC0_CCBINTLVL0_bm |
                        TC0_CCCINTLVL0_bm | TC0_CCDINTLVL0_bm;
        TCC0.INTCTRLA = TC0_ERRINTLVL0_bm;

        qPort->DIRSET = 0xFF;
        q_test_sig_Port = qPort;

        test_lineCount = lineCount;
}