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8 <h1>servo.c</h1><a href="servo_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment">00001 <span class="comment">/*! \file servo.c \brief Interrupt-driven RC Servo function library. */</span>
9 00002 <span class="comment">//*****************************************************************************</span>
10 00003 <span class="comment">//</span>
11 00004 <span class="comment">// File Name : 'servo.c'</span>
12 00005 <span class="comment">// Title : Interrupt-driven RC Servo function library</span>
13 00006 <span class="comment">// Author : Pascal Stang - Copyright (C) 2002</span>
14 00007 <span class="comment">// Created : 7/31/2002</span>
15 00008 <span class="comment">// Revised : 8/02/2002</span>
16 00009 <span class="comment">// Version : 1.0</span>
17 00010 <span class="comment">// Target MCU : Atmel AVR Series</span>
18 00011 <span class="comment">// Editor Tabs : 4</span>
19 00012 <span class="comment">//</span>
20 00013 <span class="comment">// This code is distributed under the GNU Public License</span>
21 00014 <span class="comment">// which can be found at http://www.gnu.org/licenses/gpl.txt</span>
22 00015 <span class="comment">//</span>
23 00016 <span class="comment">//*****************************************************************************</span>
24 00017
25 00018 <span class="preprocessor">#ifndef WIN32</span>
26 00019 <span class="preprocessor"></span><span class="preprocessor"> #include &lt;avr/io.h&gt;</span>
27 00020 <span class="preprocessor">#endif</span>
28 00021 <span class="preprocessor"></span>
29 00022 <span class="preprocessor">#include "<a class="code" href="global_8h.html">global.h</a>"</span>
30 00023 <span class="preprocessor">#include "<a class="code" href="servo_8h.html">servo.h</a>"</span>
31 00024
32 00025 <span class="comment">// Program ROM constants</span>
33 00026
34 00027 <span class="comment">// Global variables</span>
35 00028 <span class="comment">// servo channel registers</span>
36 00029 u16 ServoPosTics;
37 00030 u16 ServoPeriodTics;
38 00031 u08 ServoChannel;
39 00032 ServoChannelType ServoChannels[SERVO_NUM_CHANNELS];
40 00033
41 00034 <span class="comment">// functions</span>
42 00035 <span class="comment"></span>
43 00036 <span class="comment">//! initializes software PWM system</span>
44 <a name="l00037"></a><a class="code" href="servo_8h.html#a1">00037</a> <span class="comment"></span><span class="keywordtype">void</span> <a class="code" href="servo_8c.html#a4">servoInit</a>(<span class="keywordtype">void</span>)
45 00038 {
46 00039 u08 channel;
47 00040 <span class="comment">// disble the timer1 output compare A interrupt</span>
48 00041 cbi(TIMSK, OCIE1A);
49 00042 <span class="comment">// set the prescaler for timer1</span>
50 00043 <a class="code" href="group__timer.html#ga6">timer1SetPrescaler</a>(<a class="code" href="group__timer.html#ga19">TIMER_CLK_DIV256</a>);
51 00044 <span class="comment">// attach the software PWM service routine to timer1 output compare A</span>
52 00045 <a class="code" href="group__timer.html#ga8">timerAttach</a>(TIMER1OUTCOMPAREA_INT, servoService);
53 00046 <span class="comment">// enable and clear channels</span>
54 00047 <span class="keywordflow">for</span>(channel=0; channel&lt;SERVO_NUM_CHANNELS; channel++)
55 00048 {
56 00049 <span class="comment">// set minimum position as default</span>
57 00050 ServoChannels[channel].duty = SERVO_MIN;
58 00051 <span class="comment">// set default port and pins assignments</span>
59 00052 ServoChannels[channel].port = _SFR_IO_ADDR(SERVO_DEFAULT_PORT);
60 00053 <span class="comment">//ServoChannels[channel].port = (unsigned char)&amp;SERVO_DEFAULT_PORT;</span>
61 00054 ServoChannels[channel].pin = (1&lt;&lt;channel);
62 00055 <span class="comment">// set channel pin to output</span>
63 00056 <span class="comment">// THIS IS OBSOLETED BY THE DYNAMIC CHANNEL TO PORT,PIN ASSIGNMENTS</span>
64 00057 <span class="comment">//outb(SERVODDR, inb(SERVODDR) | (1&lt;&lt;channel));</span>
65 00058 }
66 00059 <span class="comment">// set PosTics</span>
67 00060 ServoPosTics = 0;
68 00061 <span class="comment">// set PeriodTics</span>
69 00062 ServoPeriodTics = SERVO_MAX*9;
70 00063 <span class="comment">// set initial interrupt time</span>
71 00064 u16 OCValue;
72 00065 <span class="comment">// read in current value of output compare register OCR1A</span>
73 00066 OCValue = inb(OCR1AL); <span class="comment">// read low byte of OCR1A</span>
74 00067 OCValue += inb(OCR1AH)&lt;&lt;8; <span class="comment">// read high byte of OCR1A</span>
75 00068 <span class="comment">// increment OCR1A value by nextTics</span>
76 00069 OCValue += ServoPeriodTics;
77 00070 <span class="comment">// set future output compare time to this new value</span>
78 00071 outb(OCR1AH, (OCValue&gt;&gt;8)); <span class="comment">// write high byte</span>
79 00072 outb(OCR1AL, (OCValue &amp; 0x00FF)); <span class="comment">// write low byte</span>
80 00073 <span class="comment">// enable the timer1 output compare A interrupt</span>
81 00074 sbi(TIMSK, OCIE1A);
82 00075 }
83 00076 <span class="comment"></span>
84 00077 <span class="comment">//! turns off software PWM system</span>
85 <a name="l00078"></a><a class="code" href="servo_8h.html#a2">00078</a> <span class="comment"></span><span class="keywordtype">void</span> <a class="code" href="servo_8c.html#a5">servoOff</a>(<span class="keywordtype">void</span>)
86 00079 {
87 00080 <span class="comment">// disable the timer1 output compare A interrupt</span>
88 00081 cbi(TIMSK, OCIE1A);
89 00082 <span class="comment">// detach the service routine</span>
90 00083 <a class="code" href="group__timer.html#ga9">timerDetach</a>(TIMER1OUTCOMPAREA_INT);
91 00084 }
92 00085 <span class="comment"></span>
93 00086 <span class="comment">//! set port and I/O pin for channel</span>
94 <a name="l00087"></a><a class="code" href="servo_8h.html#a3">00087</a> <span class="comment"></span><span class="keywordtype">void</span> <a class="code" href="servo_8c.html#a6">servoSetChannelIO</a>(u08 channel, u08 port, u08 pin)
95 00088 {
96 00089 ServoChannels[channel].port = port;
97 00090 ServoChannels[channel].pin = (1&lt;&lt;(pin&amp;0x07));
98 00091 }
99 00092 <span class="comment"></span>
100 00093 <span class="comment">//! set servo position on channel</span>
101 <a name="l00094"></a><a class="code" href="servo_8h.html#a4">00094</a> <span class="comment"></span><span class="keywordtype">void</span> <a class="code" href="servo_8c.html#a7">servoSetPosition</a>(u08 channel, u08 position)
102 00095 {
103 00096 <span class="comment">// input should be between 0 and SERVO_POSITION_MAX</span>
104 00097 u16 pos_scaled;
105 00098 <span class="comment">// calculate scaled position</span>
106 00099 pos_scaled = ((u16)position*(SERVO_MAX-SERVO_MIN)/SERVO_POSITION_MAX)+SERVO_MIN;
107 00100 <span class="comment">// set position</span>
108 00101 <a class="code" href="servo_8c.html#a9">servoSetPositionRaw</a>(channel, pos_scaled);
109 00102 }
110 00103 <span class="comment"></span>
111 00104 <span class="comment">//! get servo position on channel</span>
112 <a name="l00105"></a><a class="code" href="servo_8h.html#a5">00105</a> <span class="comment"></span>u08 <a class="code" href="servo_8c.html#a8">servoGetPosition</a>(u08 channel)
113 00106 {
114 00107 <span class="keywordflow">return</span> (u08)( ((<a class="code" href="servo_8c.html#a10">servoGetPositionRaw</a>(channel)-SERVO_MIN)*SERVO_POSITION_MAX)/(SERVO_MAX-SERVO_MIN) );
115 00108 }
116 00109 <span class="comment"></span>
117 00110 <span class="comment">//! set servo position on channel (raw unscaled format)</span>
118 <a name="l00111"></a><a class="code" href="servo_8h.html#a6">00111</a> <span class="comment"></span><span class="keywordtype">void</span> <a class="code" href="servo_8c.html#a9">servoSetPositionRaw</a>(u08 channel, u16 position)
119 00112 {
120 00113 <span class="comment">// bind to limits</span>
121 00114 position = MAX(position, SERVO_MIN);
122 00115 position = MIN(position, SERVO_MAX);
123 00116 <span class="comment">// set position</span>
124 00117 ServoChannels[channel].duty = position;
125 00118 }
126 00119 <span class="comment"></span>
127 00120 <span class="comment">//! get servo position on channel (raw unscaled format)</span>
128 <a name="l00121"></a><a class="code" href="servo_8h.html#a7">00121</a> <span class="comment"></span>u16 <a class="code" href="servo_8c.html#a10">servoGetPositionRaw</a>(u08 channel)
129 00122 {
130 00123 <span class="keywordflow">return</span> ServoChannels[channel].duty;
131 00124 }
132 00125
133 00126 <span class="keywordtype">void</span> servoService(<span class="keywordtype">void</span>)
134 00127 {
135 00128 u16 nextTics;
136 00129
137 00130 <span class="keywordflow">if</span>(ServoChannel &lt; SERVO_NUM_CHANNELS)
138 00131 {
139 00132 <span class="comment">// turn off current channel</span>
140 00133 outb(_SFR_IO8(ServoChannels[ServoChannel].port), inb(_SFR_IO8(ServoChannels[ServoChannel].port)) &amp; ~(ServoChannels[ServoChannel].pin));
141 00134 }
142 00135
143 00136 <span class="comment">// next channel</span>
144 00137 ServoChannel++;
145 00138
146 00139 <span class="keywordflow">if</span>(ServoChannel != SERVO_NUM_CHANNELS)
147 00140 {
148 00141 <span class="comment">// loop to channel 0 if needed</span>
149 00142 <span class="keywordflow">if</span>(ServoChannel &gt; SERVO_NUM_CHANNELS) ServoChannel = 0;
150 00143 <span class="comment">// turn on new channel</span>
151 00144 outb(_SFR_IO8(ServoChannels[ServoChannel].port), inb(_SFR_IO8(ServoChannels[ServoChannel].port)) | (ServoChannels[ServoChannel].pin));
152 00145 <span class="comment">// schedule turn off time</span>
153 00146 nextTics = ServoChannels[ServoChannel].duty;
154 00147 }
155 00148 <span class="keywordflow">else</span> <span class="comment">//(Channel == SERVO_NUM_CHANNELS)</span>
156 00149 {
157 00150 <span class="comment">// ***we could save time by precalculating this</span>
158 00151 <span class="comment">// schedule end-of-period</span>
159 00152 nextTics = ServoPeriodTics-ServoPosTics;
160 00153 }
161 00154
162 00155 <span class="comment">// schedule next interrupt</span>
163 00156 u16 OCValue;
164 00157 <span class="comment">// read in current value of output compare register OCR1A</span>
165 00158 OCValue = inb(OCR1AL); <span class="comment">// read low byte of OCR1A</span>
166 00159 OCValue += inb(OCR1AH)&lt;&lt;8; <span class="comment">// read high byte of OCR1A</span>
167 00160 <span class="comment">// increment OCR1A value by nextTics</span>
168 00161 OCValue += nextTics;
169 00162 <span class="comment">// OCR1A+=nextTics;</span>
170 00163 <span class="comment">// set future output compare time to this new value</span>
171 00164 outb(OCR1AH, (OCValue&gt;&gt;8)); <span class="comment">// write high byte</span>
172 00165 outb(OCR1AL, (OCValue &amp; 0x00FF)); <span class="comment">// write low byte</span>
173 00166 <span class="comment">// set our new tic position</span>
174 00167 ServoPosTics += nextTics;
175 00168 <span class="keywordflow">if</span>(ServoPosTics &gt;= ServoPeriodTics) ServoPosTics = 0;
176 00169 }
177 </pre></div><hr size="1"><address style="align: right;"><small>Generated on Sun Oct 29 03:41:07 2006 for Procyon AVRlib by&nbsp;
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