root / trunk / code / projects / colonet / robot / wl_network_colonet / analog.c @ 481
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1 | 13 | emarinel | /*
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2 | analog.c - Contains the function implementations for manipulating the ADC
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3 | on the firefly+ board
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4 | |||
5 | author: CMU Robotics Club, Colony Project
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6 | code mostly taken from fwr analog file (author: Tom Lauwers)
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7 | */
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8 | |||
9 | #include <avr/delay.h> |
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10 | #include <avr/interrupt.h> |
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11 | #include <avr/signal.h> |
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12 | #include "analog.h" |
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13 | |||
14 | void analog_init(void){ |
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15 | |||
16 | /*
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17 | ADC Status Register A
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18 | Bit 7 - ADEN is set (enables analog)
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19 | Bit 6 - Start conversion bit is set (must be done once for free-running mode)
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20 | Bit 5 - Enable Auto Trigger (for free running mode)
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21 | Bit 3 - Enable ADC Interrupt (required to run free-running mode)
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22 | Bits 2-0 - Set to create a clock divisor of 128, to make ADC clock = 16,000,000/128
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23 | */
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24 | ADCSRA |= 0xEF;
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25 | |||
26 | /*
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27 | ADMUX register
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28 | Bit 7,6 - Set voltage reference to AVcc (0b01)
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29 | Bit 5 - Set ADLAR bit for left adjust to do simple 8-bit reads
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30 | Bit 4 - X
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31 | Bit 3:0 - Sets the current channel
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32 | */
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33 | ADMUX = 0x67;
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34 | } |
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35 | |||
36 | unsigned int analog8(int which){ |
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37 | ADMUX = 0x60 + which;
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38 | _delay_ms(1); // need at least 130 us between conversions (for fwr robot, how much for new avr?) |
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39 | return ADCH;
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40 | } |
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41 | |||
42 | unsigned int analog10(int which){ |
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43 | unsigned int adc_h = 0; |
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44 | unsigned int adc_l = 0; |
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45 | |||
46 | ADMUX = 0x60 + which;
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47 | _delay_ms(1);
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48 | adc_l = ADCL; /* highest 2 bits of ADCL -> least 2 bits of analog val */
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49 | adc_h = ADCH; /* ADCH -> 8 highest bits of analog val */
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50 | |||
51 | return (adc_h << 2) | (adc_l >> 6); |
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52 | } |
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53 | |||
54 | int wheel(void){ |
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55 | return analog8(WHEEL_PORT);
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56 | } |
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57 | |||
58 | int battery(void){ |
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59 | return analog8(BATT_PORT) * 500 / 255; /* 5 volts is the max, 255 is the max 8bit number */ |
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60 | } |
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61 | |||
62 | SIGNAL (SIG_ADC) |
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63 | { |
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64 | // This is just here to catch ADC interrupts because ADC is free running.
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65 | // No code needs to be in here.
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66 | } |