Colony

/**

 * Copyright (c) 2007 Colony Project

 * 

 * Permission is hereby granted, free of charge, to any person

 * obtaining a copy of this software and associated documentation

 * files (the "Software"), to deal in the Software without

 * restriction, including without limitation the rights to use,

 * copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following

 * conditions:

 * 

 * The above copyright notice and this permission notice shall be

 * included in all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES

 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT

 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,

 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

 * OTHER DEALINGS IN THE SOFTWARE.

 **/

/**

 * @file analog.c

 * @brief Analog input and output

 *

 * Contains functions for manipulating the ADC on the Dragonfly board.

 * 

 * @author Colony Project, CMU Robotics Club

 * originally taken from fwr analog file (author: Tom Lauwers)

 * loop code written by Kevin Woo and James Kong

 **/

#include <util/delay.h>

#include <avr/interrupt.h>

#include "analog.h"

#include "serial.h"

// Internal Function Prototypes

void set_adc_mux(int which);

/**

 * @defgroup analog Analog

 * Functions for manipulation the ADC on the dragonfly board.

 * All definitions may be found in analog.h.

 *

 * @{

 **/

volatile int adc_loop_status = ADC_LOOP_STOPPED;

volatile int adc_sig_stop_loop = 0;

volatile int adc_current_port = 0;

volatile adc_t an_val[11];

/**

 * Initializes the ADC.

 * Call analog_init before reading from the analog ports.

 *

 * @see analog8, analog10, analog_get8, analog_get10

 *

 * @bug First conversion takes a performance penalty of

 * 25 vs. 13 ADC clock cycles of successive conversions.

 * Analog_init should run a dummy conversion to pre-empt

 * this.

 *

 * For good 10-bit precision, ACD clock must be between

 * 50kHz and 200kHz. Currently, ADC clock is fixed at

 * 125kHz using 1/64prescalar. However, most code uses

 * 8-bit precision which can work at ADC clock speeds

 * higher than 200kHz. Experimental tests needed to

 * determine highest clock speed for accurate 8-bit ADC.

 *

 **/

void analog_init(int start_conversion) {

        start_conversion=0;                   //forces the analog loop off

        for (int i = 0; i < 11; i++) {

                an_val[i].adc10 = 0;

                an_val[i].adc8 = 0;

        }

        // ADMUX register

        // Bit 7,6 - Set voltage reference to AVcc (0b01)

        // Bit 5 - ADLAR set to simplify moving from register

        // Bit 4 - X

        // Bit 3:0 - Sets the current channel

        // Initializes to read from AN1 first (AN0 is reservered for the BOM)

        ADMUX = 0;

        ADMUX |= ADMUX_OPT | _BV(MUX0);

        // ADC Status Register A

        // Bit 7 - ADEN is set (enables analog)

        // Bit 6 - Start conversion bit is set (must be done once for free-running mode)

        // Bit 5 - Enable Auto Trigger (for free running mode) NOT DOING THIS RIGHT NOW

        // Bit 4 - ADC interrupt flag, 0

        // Bit 3 - Enable ADC Interrupt (required to run free-running mode)

        // Bits 2-0 - Set to create a clock divisor of 2, to make ADC clock != 8,000,000/64 = 125kHz (it runs at highest frequency)

        ADCSRA = 0;

        ADCSRA |= _BV(ADEN) | /*_BV(ADPS2) | _BV(ADPS1) |*/ _BV(ADPS0);

        // Set external mux lines to outputs

        DDRG |= 0x1C;

        // Set up first port for conversions

        set_adc_mux(0x00);

        adc_current_port = AN1;

        //Conversion loop disabled by default

}        

/**

 * Returns the 8-bit analog conversion of which from

 * the lookup table. If the requested port is the BOM_PORT

 * you will get an automatic 0 since the BOM_PORT is not

 * read in the loop and not stored. If you need that port

 * you should use the functions in bom.c. There is an analog_get8

 * function which for instant lookups but should be avoided unless

 * you know what you're doing.

 *

 * @param which the port that you want to read

 *

 * @bug may cause a seg fault if which is a larger value

 * than exists in an_val table. Not sure if we should fix

 * this or not since it would add overhead.

 *

 * @return 8-bit analog value for the which port requested

 *

 * @see analog10, analog_get8, analog_get10

 **/

unsigned int analog8(int which) {

/*        if (which == BOM_PORT) {

                return 0;

        } else {

                return an_val[which - 1].adc8;

        }

*/

return analog_get8(which);

}

/**

 * Returns the 10-bit analog conversion of which from

 * the lookup table. If the requested port is the BOM_PORT

 * you will get an automatic 0 since the BOM_PORT is not

 * read in the loop and not stored. If you need that port

 * you should use the functions in bom.c. There is an analog_get10

 * function which for instant lookups but should be avoided unless

 * you know what you are doing.

 *

 * @param which the port that you want to read

 *

 * @bug may cause a seg fault if which is a larger value

 * than exists in an_val table. Not sure if we should fix

 * this or not since it would add overhead.

 *

 * @return 10-bit analog value for the which port requested

 *

 * @see analog8, analog_get8, analog_get10

 **/

unsigned int analog10(int which) {

/*        if (which == BOM_PORT) {

                return 0;

        } else {

                return an_val[which - 1].adc10;

        }

*/

return analog_get10(which);

}

/**

 * Starts the analog update loop. Will continue to run

 * until analog_stop_loop is called.

 *

 * @see analog_stop_loop, analog_loop_status

 **/

void analog_start_loop(void) {

        if(adc_loop_status != ADC_LOOP_RUNNING){

                //Start the conversion, enable ADC interrupt

                ADCSRA |= _BV(ADIE);

                ADCSRA |= _BV(ADSC);

                adc_loop_status = ADC_LOOP_RUNNING;

        }

}

/**

 * Stops the analog update loop. If there is a current

 * read, it will finish up and be stored before the loop

 * is interrupted. No further updates will be made until

 * the loop is started again.

 *

 * @see analog_start_loop, analog_loop_status

 **/

void analog_stop_loop() {

        //Signal to stop after the next conversion

        adc_sig_stop_loop = 1;

}

/**

 * Returns the status of loop. 0 for stopped.

 * 1 for running. 2 for paused.

 *

 * @see analog_start_loop, analog_stop_loop

 **/

int analog_loop_status(void) {

        return adc_loop_status;

}

/**

 * Reads an 8-bit number from an analog port.

 * analog_init must be called before using this function.

 * The analog loop must also be stopped before using this

 * function or you will mess up the lookup table. You

 * must also reenabled the loop when you are done unless

 * you are doing more instant reads. See analog_stop_loop

 * and analog_start_loop for more information about the loop.

 * 

 * @param which the analog port to read from. One of

 * the constants AN0 - AN7.

 *

 * @return the 8-bit input to the specified port

 *

 * @see analog_init, analog_get10, analog8, analog_stop_loop,

 * analog_start_loop

 **/

unsigned int analog_get8(int which) {        

        // Let any previous conversion finish

        while (ADCSRA & _BV(ADSC));

        if(which < EXT_MUX) {

                ADMUX = ADMUX_OPT + which;

        } else {

                ADMUX = ADMUX_OPT + EXT_MUX;

                set_adc_mux(which - 8);

        }

        // Start the conversion

        ADCSRA |= _BV(ADSC);

        // Wait for the conversion to finish

        while (ADCSRA & _BV(ADSC));

        return ADCH; //since we left aligned the data, ADCH is the 8 MSB.

}

/**

 * Reads an 10-bit number from an analog port.

 * analog_init must be called before using this function.

 * The analog loop must also be stopped before using this

 * function or you will mess up the lookup table. You

 * must also reenabled the loop when you are done unless

 * you are doing more instant reads. See analog_stop_loop

 * and analog_start_loop for more information about the loop.

 * 

 *

 * @param which the analog port to read from. Typically

 * a constant, one of AN0 - AN7.

 *

 * @return the 10-bit number input to the specified port

 * 

 * @see analog_init, analog_get8, analog10, analog_stop_loop,

 * analog_start_loop

 **/

unsigned int analog_get10(int which) {

        int adc_h;

        int adc_l;

        // Let any previous conversion finish

        while (ADCSRA & _BV(ADSC));

        if(which < EXT_MUX) {

                ADMUX = ADMUX_OPT + which;

        } else {

                ADMUX = ADMUX_OPT + EXT_MUX;

                set_adc_mux(which - 8);

        }

        // Start the conversion

        ADCSRA |= _BV(ADSC);

        // Wait for the conversion to finish

        while (ADCSRA & _BV(ADSC));

        adc_l = ADCL;

        adc_h = ADCH;

        return ((adc_h << 2) | (adc_l >> 6));

}

/**

 * Returns the current position of the wheel, as an integer

 * in the range 0 - 255.

 * analog_init must be called before using this function.

 *

 * @return the orientation of the wheel, as an integer in

 * the range 0 - 255.

 *

 * @see analog_init

 **/

int wheel(void) {

        return analog8(WHEEL_PORT);

}

/**

 * Sets the value of the external analog mux. Values are read

 *         on AN7 physical port. (AN8 - AN15 are "virtual" ports).

 *

 * @param which which analog mux port (0-7) which corresponds

 *                   to AN8-AN15.

 *

 * @bug FIX THIS IN THE NEXT BOARD REVISION:

 *                ADDR2 ADDR1 ADDR0

 *                G2.G4.G3 set mux to port 0-7 via vinary selection

 *                math would be much cleaner if it was G4.G3.G2

 *

 * @see analog_init

 **/

void set_adc_mux(int which) {  

  // mask so only proper bits are possible.  

  PORTG = (PORTG & 0xE3) | ((which & 0x03) << 3) | (which & 0x04);

}

/**@}**/ //end defgroup