root / trunk / code / projects / libdragonfly / battery.c @ 874
History | View | Annotate | Download (3.78 KB)
1 | 241 | bcoltin | /**
|
---|---|---|---|
2 | * Copyright (c) 2007 Colony Project
|
||
3 | *
|
||
4 | * Permission is hereby granted, free of charge, to any person
|
||
5 | * obtaining a copy of this software and associated documentation
|
||
6 | * files (the "Software"), to deal in the Software without
|
||
7 | * restriction, including without limitation the rights to use,
|
||
8 | * copy, modify, merge, publish, distribute, sublicense, and/or sell
|
||
9 | * copies of the Software, and to permit persons to whom the
|
||
10 | * Software is furnished to do so, subject to the following
|
||
11 | * conditions:
|
||
12 | *
|
||
13 | * The above copyright notice and this permission notice shall be
|
||
14 | * included in all copies or substantial portions of the Software.
|
||
15 | *
|
||
16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
|
||
17 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
|
||
18 | * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
|
||
19 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
|
||
20 | * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
|
||
21 | * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
|
||
22 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
|
||
23 | * OTHER DEALINGS IN THE SOFTWARE.
|
||
24 | **/
|
||
25 | |||
26 | |||
27 | /**
|
||
28 | * @file battery.c
|
||
29 | * @brief Implementation for reading battery level
|
||
30 | *
|
||
31 | * Contains functions for reading the battery level.
|
||
32 | *
|
||
33 | * @author Colony Project, CMU Robotics Club
|
||
34 | **/
|
||
35 | |||
36 | 8 | bcoltin | #include "battery.h" |
37 | #include "analog.h" |
||
38 | |||
39 | //Constants for Battery
|
||
40 | //Constants determined experimentally 2/9/2007 - James Kong
|
||
41 | //See Battery8_data.xls for experiment data
|
||
42 | #define BATTERY_NEXT_READ_PRESCALAR 5 |
||
43 | #define MAX_LOW_COUNT 5 |
||
44 | |||
45 | //global variables
|
||
46 | int battery_low_count;
|
||
47 | |||
48 | /**
|
||
49 | * @defgroup battery Battery
|
||
50 | * @brief Functions for reading battery voltage.
|
||
51 | *
|
||
52 | * Contains functions for checking the current
|
||
53 | * voltage of the battery. Include battery.h to
|
||
54 | * access these functions.
|
||
55 | *
|
||
56 | * @{
|
||
57 | **/
|
||
58 | |||
59 | /**
|
||
60 | * Returns the voltage of the battery as an analog8
|
||
61 | * reading. 128 is approximately 5 volts. analog_init
|
||
62 | * must be called before using this function.
|
||
63 | *
|
||
64 | * @return the voltage of the battery as an analog8
|
||
65 | * reading
|
||
66 | *
|
||
67 | * @see analog_init, battery, analog8
|
||
68 | **/
|
||
69 | int battery8(void) |
||
70 | { |
||
71 | return analog8(BATT_PORT);
|
||
72 | } |
||
73 | |||
74 | /**
|
||
75 | * Returns the voltage of the battery in deciVolts.
|
||
76 | * analog_init must be called before using this function.
|
||
77 | *
|
||
78 | * @return the voltage of the battery in deciVolts.
|
||
79 | *
|
||
80 | * @see analog_init, battery8
|
||
81 | **/
|
||
82 | int battery(void) |
||
83 | { |
||
84 | /* 5 volts is the max, 255 is the max 8bit number , *2 for the divider */
|
||
85 | return analog8(BATT_PORT) * 500 >>7; |
||
86 | } |
||
87 | |||
88 | |||
89 | /**
|
||
90 | * Checks if the battery is low. analog_init must be called before
|
||
91 | * this function can be used. This function waits for several low
|
||
92 | * battery readings in a row to avoid false positives.
|
||
93 | *
|
||
94 | * @return 1 if the battery is low, 0 otherwise
|
||
95 | *
|
||
96 | * @see analog_init
|
||
97 | **/
|
||
98 | char battery_low(void) |
||
99 | { |
||
100 | static char next_read = 0; |
||
101 | static char ret = 0; |
||
102 | |||
103 | int batt_reading = battery8();
|
||
104 | |||
105 | 377 | kwoo | if(next_read == 0) |
106 | { |
||
107 | 8 | bcoltin | if(batt_reading > BATTERY_LOWV)
|
108 | { |
||
109 | ret = 0;
|
||
110 | battery_low_count = 0;
|
||
111 | } |
||
112 | else
|
||
113 | { |
||
114 | battery_low_count++; |
||
115 | if( battery_low_count >= MAX_LOW_COUNT )
|
||
116 | { |
||
117 | ret = 1;
|
||
118 | battery_low_count = 0;
|
||
119 | } |
||
120 | } |
||
121 | |||
122 | next_read = BATTERY_NEXT_READ_PRESCALAR; |
||
123 | } |
||
124 | else next_read--;
|
||
125 | |||
126 | return ret;
|
||
127 | } |
||
128 | |||
129 | /**
|
||
130 | * Averages n_samples battery8 readings. This function may
|
||
131 | * take a while to complete, and is only made available
|
||
132 | * for convenience. analog_init must be called before this
|
||
133 | * function may be used.
|
||
134 | *
|
||
135 | 241 | bcoltin | * @param n_samples the number of times to sample the battery voltage
|
136 | 8 | bcoltin | *
|
137 | * @return the average reading for the battery voltage, where 128
|
||
138 | * is approximately 5 Volts.
|
||
139 | *
|
||
140 | * @see analog_init, battery
|
||
141 | **/
|
||
142 | int battery8_avg(int n_samples) |
||
143 | { |
||
144 | int i;
|
||
145 | long int sum = 0; |
||
146 | |||
147 | 377 | kwoo | for(i = 0; i < n_samples; i++) |
148 | { |
||
149 | 8 | bcoltin | sum += battery8(); |
150 | } |
||
151 | |||
152 | return (int)(sum / n_samples); |
||
153 | } |
||
154 | |||
155 | /** @} **/ //end defgroup |