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root / trunk / code / projects / colonet / testing / wl_network_colonet / analog.c @ 13

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/*
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        analog.c - Contains the function implementations for manipulating the ADC
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        on the firefly+ board
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        author:  CMU Robotics Club, Colony Project
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        code mostly taken from fwr analog file (author: Tom Lauwers)
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*/
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#include <avr/delay.h>
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#include <avr/interrupt.h>
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#include <avr/signal.h>
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#include "analog.h"
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void analog_init(void){
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        /*
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                ADC Status Register A
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                Bit 7 - ADEN is set (enables analog)
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                Bit 6 - Start conversion bit is set (must be done once for free-running mode)
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                Bit 5 - Enable Auto Trigger (for free running mode)
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                Bit 3 - Enable ADC Interrupt (required to run free-running mode)
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                Bits 2-0 - Set to create a clock divisor of 128, to make ADC clock = 16,000,000/128
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        */
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        ADCSRA |= 0xEF;
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        /*
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                ADMUX register
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                Bit 7,6 - Set voltage reference to AVcc (0b01)
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                Bit 5 - Set ADLAR bit for left adjust to do simple 8-bit reads
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                Bit 4 - X
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                Bit 3:0 - Sets the current channel
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        */
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        ADMUX = 0x67;
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}        
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unsigned int analog8(int which){
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        ADMUX = 0x60 + which;
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        _delay_ms(1); // need at least 130 us between conversions (for fwr robot, how much for new avr?)
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        return ADCH;
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}
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unsigned int analog10(int which){
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        unsigned int adc_h = 0;
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        unsigned int adc_l = 0;
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        ADMUX = 0x60 + which;
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        _delay_ms(1);
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        adc_l = ADCL; /* highest 2 bits of ADCL -> least 2 bits of analog val */
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        adc_h = ADCH; /* ADCH -> 8 highest bits of analog val */
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        return (adc_h << 2) | (adc_l >> 6);
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}
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int wheel(void){
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        return analog8(WHEEL_PORT);
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}
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int battery(void){
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        return analog8(BATT_PORT) * 500 / 255; /* 5 volts is the max, 255 is the max 8bit number */
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}
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SIGNAL (SIG_ADC)
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{
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        // This is just here to catch ADC interrupts because ADC is free running.  
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        // No code needs to be in here.
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}