1 /*
2 wiring_analog.c - analog input and output
3 Part of Arduino - http://www.arduino.cc/
4
5 Copyright (c) 2005-2006 David A. Mellis
6
7 This library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
11
12 This library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General
18 Public License along with this library; if not, write to the
19 Free Software Foundation, Inc., 59 Temple Place, Suite 330,
20 Boston, MA 02111-1307 USA
21
22 Modified 28 September 2010 by Mark Sproul
23
24 $Id: wiring.c 248 2007-02-03 15:36:30Z mellis $
25 */
26
27 #include "wiring_private.h"
28 #include "pins_arduino.h"
29
30 uint8_t analog_reference = DEFAULT;
31
analogReference(uint8_t mode)32 void analogReference(uint8_t mode)
33 {
34 // can't actually set the register here because the default setting
35 // will connect AVCC and the AREF pin, which would cause a short if
36 // there's something connected to AREF.
37 analog_reference = mode;
38 }
39
analogRead(uint8_t pin)40 int analogRead(uint8_t pin)
41 {
42 uint8_t low, high;
43
44 #if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
45 if (pin >= 54) pin -= 54; // allow for channel or pin numbers
46 #else
47 if (pin >= 14) pin -= 14; // allow for channel or pin numbers
48 #endif
49
50 #if defined(ADCSRB) && defined(MUX5)
51 // the MUX5 bit of ADCSRB selects whether we're reading from channels
52 // 0 to 7 (MUX5 low) or 8 to 15 (MUX5 high).
53 ADCSRB = (ADCSRB & ~(1 << MUX5)) | (((pin >> 3) & 0x01) << MUX5);
54 #endif
55
56 // set the analog reference (high two bits of ADMUX) and select the
57 // channel (low 4 bits). this also sets ADLAR (left-adjust result)
58 // to 0 (the default).
59 #if defined(ADMUX)
60 ADMUX = (analog_reference << 6) | (pin & 0x07);
61 #endif
62
63 // without a delay, we seem to read from the wrong channel
64 //delay(1);
65
66 #if defined(ADCSRA) && defined(ADCL)
67 // start the conversion
68 sbi(ADCSRA, ADSC);
69
70 // ADSC is cleared when the conversion finishes
71 while (bit_is_set(ADCSRA, ADSC));
72
73 // we have to read ADCL first; doing so locks both ADCL
74 // and ADCH until ADCH is read. reading ADCL second would
75 // cause the results of each conversion to be discarded,
76 // as ADCL and ADCH would be locked when it completed.
77 low = ADCL;
78 high = ADCH;
79 #else
80 // we dont have an ADC, return 0
81 low = 0;
82 high = 0;
83 #endif
84
85 // combine the two bytes
86 return (high << 8) | low;
87 }
88
89 // Right now, PWM output only works on the pins with
90 // hardware support. These are defined in the appropriate
91 // pins_*.c file. For the rest of the pins, we default
92 // to digital output.
analogWrite(uint8_t pin,int val)93 void analogWrite(uint8_t pin, int val)
94 {
95 // We need to make sure the PWM output is enabled for those pins
96 // that support it, as we turn it off when digitally reading or
97 // writing with them. Also, make sure the pin is in output mode
98 // for consistenty with Wiring, which doesn't require a pinMode
99 // call for the analog output pins.
100 pinMode(pin, OUTPUT);
101 if (val == 0)
102 {
103 digitalWrite(pin, LOW);
104 }
105 else if (val == 255)
106 {
107 digitalWrite(pin, HIGH);
108 }
109 else
110 {
111 switch(digitalPinToTimer(pin))
112 {
113 // XXX fix needed for atmega8
114 #if defined(TCCR0) && defined(COM00) && !defined(__AVR_ATmega8__)
115 case TIMER0A:
116 // connect pwm to pin on timer 0
117 sbi(TCCR0, COM00);
118 OCR0 = val; // set pwm duty
119 break;
120 #endif
121
122 #if defined(TCCR0A) && defined(COM0A1)
123 case TIMER0A:
124 // connect pwm to pin on timer 0, channel A
125 sbi(TCCR0A, COM0A1);
126 OCR0A = val; // set pwm duty
127 break;
128 #endif
129
130 #if defined(TCCR0A) && defined(COM0B1)
131 case TIMER0B:
132 // connect pwm to pin on timer 0, channel B
133 sbi(TCCR0A, COM0B1);
134 OCR0B = val; // set pwm duty
135 break;
136 #endif
137
138 #if defined(TCCR1A) && defined(COM1A1)
139 case TIMER1A:
140 // connect pwm to pin on timer 1, channel A
141 sbi(TCCR1A, COM1A1);
142 OCR1A = val; // set pwm duty
143 break;
144 #endif
145
146 #if defined(TCCR1A) && defined(COM1B1)
147 case TIMER1B:
148 // connect pwm to pin on timer 1, channel B
149 sbi(TCCR1A, COM1B1);
150 OCR1B = val; // set pwm duty
151 break;
152 #endif
153
154 #if defined(TCCR2) && defined(COM21)
155 case TIMER2:
156 // connect pwm to pin on timer 2
157 sbi(TCCR2, COM21);
158 OCR2 = val; // set pwm duty
159 break;
160 #endif
161
162 #if defined(TCCR2A) && defined(COM2A1)
163 case TIMER2A:
164 // connect pwm to pin on timer 2, channel A
165 sbi(TCCR2A, COM2A1);
166 OCR2A = val; // set pwm duty
167 break;
168 #endif
169
170 #if defined(TCCR2A) && defined(COM2B1)
171 case TIMER2B:
172 // connect pwm to pin on timer 2, channel B
173 sbi(TCCR2A, COM2B1);
174 OCR2B = val; // set pwm duty
175 break;
176 #endif
177
178 #if defined(TCCR3A) && defined(COM3A1)
179 case TIMER3A:
180 // connect pwm to pin on timer 3, channel A
181 sbi(TCCR3A, COM3A1);
182 OCR3A = val; // set pwm duty
183 break;
184 #endif
185
186 #if defined(TCCR3A) && defined(COM3B1)
187 case TIMER3B:
188 // connect pwm to pin on timer 3, channel B
189 sbi(TCCR3A, COM3B1);
190 OCR3B = val; // set pwm duty
191 break;
192 #endif
193
194 #if defined(TCCR3A) && defined(COM3C1)
195 case TIMER3C:
196 // connect pwm to pin on timer 3, channel C
197 sbi(TCCR3A, COM3C1);
198 OCR3C = val; // set pwm duty
199 break;
200 #endif
201
202 #if defined(TCCR4A) && defined(COM4A1)
203 case TIMER4A:
204 // connect pwm to pin on timer 4, channel A
205 sbi(TCCR4A, COM4A1);
206 OCR4A = val; // set pwm duty
207 break;
208 #endif
209
210 #if defined(TCCR4A) && defined(COM4B1)
211 case TIMER4B:
212 // connect pwm to pin on timer 4, channel B
213 sbi(TCCR4A, COM4B1);
214 OCR4B = val; // set pwm duty
215 break;
216 #endif
217
218 #if defined(TCCR4A) && defined(COM4C1)
219 case TIMER4C:
220 // connect pwm to pin on timer 4, channel C
221 sbi(TCCR4A, COM4C1);
222 OCR4C = val; // set pwm duty
223 break;
224 #endif
225
226 #if defined(TCCR5A) && defined(COM5A1)
227 case TIMER5A:
228 // connect pwm to pin on timer 5, channel A
229 sbi(TCCR5A, COM5A1);
230 OCR5A = val; // set pwm duty
231 break;
232 #endif
233
234 #if defined(TCCR5A) && defined(COM5B1)
235 case TIMER5B:
236 // connect pwm to pin on timer 5, channel B
237 sbi(TCCR5A, COM5B1);
238 OCR5B = val; // set pwm duty
239 break;
240 #endif
241
242 #if defined(TCCR5A) && defined(COM5C1)
243 case TIMER5C:
244 // connect pwm to pin on timer 5, channel C
245 sbi(TCCR5A, COM5C1);
246 OCR5C = val; // set pwm duty
247 break;
248 #endif
249
250 case NOT_ON_TIMER:
251 default:
252 if (val < 128) {
253 digitalWrite(pin, LOW);
254 } else {
255 digitalWrite(pin, HIGH);
256 }
257 }
258 }
259 }
260