qdec_example.c File Reference

The XMEGA Quadrature Decoder example source code. More...

#include "avr_compiler.h"
#include "qdec_driver.h"
#include "qdec_signal_generator.h"

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Macros
#define	CLOCK_DIV   64
#define	CLOCK_DIV_bm   TC_CLKSEL_DIV64_gc
	Defines the clock division for the timer used. if changed both defines NEED to be changed correspondingly. More...

Functions
int	main (void)
	Quadrature decoding example. More...

Variables
uint16_t	calcFreq = 0
uint16_t	calcRPM = 0
uint16_t	captureFreq = 0
	Global frequency variable. More...
bool	dir = CW_DIR
	Direction of the output signal. More...
uint8_t	freq = 60
	If GENERATE_TEST_SIGNAL is defined the system generates a test signal with frequency equal to freq (RPM = freq*60). More...
uint8_t	lineCount = 30
	Number of lines in the quadrature encoder. More...

Detailed Description

The XMEGA Quadrature Decoder example source code.

This file contains example code that demonstrate the quadrature decoder. It shows how to set up the event system and the Timer/Counter to decode the angle of rotation from a quadrature encoder.

Application note:

AVR1600: Using the XMEGA Quadrature Decoder

Documentation

For comprehensive code documentation, supported compilers, compiler settings and supported devices see readme.html

Author

Former Atmel Corporation: http://www.microchip.com

Revision

7626

Date

2017-09-07 11:28:20 +0200 (to, 07 sep 2017)

Copyright (c) 2008, Atmel Corporation All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. The name of ATMEL may not be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Definition in file qdec_example.c.

Macro Definition Documentation

CLOCK_DIV

#define CLOCK_DIV   64

Definition at line 69 of file qdec_example.c.

Referenced by main().

CLOCK_DIV_bm

#define CLOCK_DIV_bm   TC_CLKSEL_DIV64_gc

Defines the clock division for the timer used. if changed both defines NEED to be changed correspondingly.

Definition at line 68 of file qdec_example.c.

Referenced by main().

Function Documentation

main()

int main

(

void

)

Quadrature decoding example.

This is the main example code demonstrating the setup and configuration to make the quadrature decoder work. The example use the event system and a Timer/Counter to decode the signals and the counter value in the Timer/Counter will reflect the angle of rotation. The direction bit in the TC reflect the current direction of rotation.

Hardware setup:

• PD0 - QDPH0
• PD1 - QDPH90
• PD2 - QDINDX

Peripherals used:

• PORTD[2:0] signal input.
• Event channel 0: quadrature signal.
• Event channel 1: index signal.
• TCC0: Quadrature counter.

Definition at line 98 of file qdec_example.c.

References calcFreq, calcRPM, CLOCK_DIV, CLOCK_DIV_bm, dir, F_CPU, freq, generate_qdec_signal(), GetCaptureValue, lineCount, QDEC_TC_Freq_Setup(), and QDEC_Total_Setup().

{
        /* Set up port C as output. */
        PORTC.DIRSET = 0xFF;

        /* Setup PORTD with pin 0 as input for QDPH0, dont invert IO pins.
         *
         * Setup event channel 0, pin 0 on PORTD as input, don't enable index.
         * if index used then state 00 is set as the index reset state.
         *
         * Setup TCC0 with Event channel 0 and lineCount.
         */
        QDEC_Total_Setup(&PORTD,                    /*PORT_t * qPort*/
                         0,                         /*uint8_t qPin*/
                         false,                     /*bool invIO*/
                         0,                         /*uint8_t qEvMux*/
                         EVSYS_CHMUX_PORTD_PIN0_gc, /*EVSYS_CHMUX_t qPinInput*/
                         false,                     /*bool useIndex*/
                         EVSYS_QDIRM_00_gc,         /*EVSYS_QDIRM_t qIndexState*/
                         &TCC0,                     /*TC0_t * qTimer*/
                         TC_EVSEL_CH0_gc,           /*TC_EVSEL_t qEventChannel*/
                         lineCount);                /*uint8_t lineCount*/

        /* Setup TCD0 with Event channel 2 for same pin as QDPH0 and clk div 64. */
        QDEC_TC_Freq_Setup(&TCD0, TC_EVSEL_CH2_gc, EVSYS_CHMUX_PORTD_PIN0_gc, CLOCK_DIV_bm);

#ifdef GENERATE_TEST_SIGNAL
        /* Initialize and start outputting quadrature signal.*/
        generate_qdec_signal(&PORTE, lineCount, freq, dir);

        /* Enable low level interrupt.*/
        PMIC.CTRL |= PMIC_LOLVLEN_bm;

        /* Enable global interrupts.*/
        sei();
#endif
        
        /* Display the frequency of rotation on LEDs */
        while (1) {

                if ((TCD0.INTFLAGS & TC0_CCAIF_bm) !=  0) {
                        /* Period of counter ticks are 1/(F_CPU/clk_div)
                         * Real tick count is 4 times captured value
                         * (when used with quadratur signal).
                         * Real frequency is then (F_CPU/clk_div)/(capture_value * linecount)
                         * For output in RPM multiply frequency by 60 (60 sec per min).*/
                        calcFreq = (F_CPU / CLOCK_DIV) /
                                   ((GetCaptureValue(TCD0) & 0xFFFC) * lineCount );
                        calcRPM = calcFreq*60;
                        PORTC.OUT = ~(calcFreq);
                }
        }
}

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Variable Documentation

calcFreq

uint16_t calcFreq = 0

Definition at line 76 of file qdec_example.c.

Referenced by main().

calcRPM

uint16_t calcRPM = 0

Definition at line 77 of file qdec_example.c.

Referenced by main().

captureFreq

uint16_t captureFreq = 0

Global frequency variable.

Definition at line 75 of file qdec_example.c.

dir

bool dir = CW_DIR

Direction of the output signal.

Definition at line 63 of file qdec_example.c.

Referenced by main().

freq

uint8_t freq = 60

If GENERATE_TEST_SIGNAL is defined the system generates a test signal with frequency equal to freq (RPM = freq*60).

Output frequency when system generates a signal

Definition at line 60 of file qdec_example.c.

Referenced by main().

lineCount

uint8_t lineCount = 30

Number of lines in the quadrature encoder.

Definition at line 72 of file qdec_example.c.

Referenced by generate_qdec_signal(), and main().