4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2007 Develer S.r.l. (http://www.develer.com/)
32 * \brief ADC hardware-specific definition
35 * \author Francesco Sacchi <batt@develer.com>
40 #include <cfg/cfg_adc.h>
41 #include <cfg/cfg_kern.h>
42 #include <cfg/macros.h>
43 #include <cfg/compiler.h>
48 #include <avr/interrupt.h>
50 #define ADC_AVR_AREF 0
51 #define ADC_AVR_AVCC 1
52 #define ADC_AVR_INT256 2
55 #include <cfg/module.h>
56 #include <kern/proc.h>
57 #include <kern/signal.h>
60 #if !CONFIG_KERN_SIGNALS
61 #error Signals must be active to use ADC with kernel
64 /* Signal adc convertion end */
65 #define SIG_ADC_COMPLETE SIG_SINGLE
67 /* ADC waiting process */
68 static struct Process *adc_process;
72 * Simply signal the adc process that convertion is complete.
76 sig_signal(adc_process, SIG_ADC_COMPLETE);
78 #endif /* CONFIG_KERNEL */
81 * Select mux channel \a ch.
82 * \todo only first 8 channels are selectable!
84 INLINE void adc_hw_select_ch(uint8_t ch)
86 /* Set to 0 all mux registers */
87 ADMUX &= ~(BV(MUX3) | BV(MUX3) | BV(MUX2) | BV(MUX1) | BV(MUX0));
89 /* Select channel, only first 8 channel modes are supported for now */
95 * Start an ADC convertion.
96 * If a kernel is present, preempt until convertion is complete, otherwise
97 * a busy wait on ADCS bit is done.
99 INLINE uint16_t adc_hw_read(void)
101 // Ensure another convertion is not running.
102 ASSERT(!(ADCSRA & BV(ADSC)));
108 // Ensure IRQs enabled.
109 ASSERT(IRQ_ENABLED());
110 adc_process = proc_current();
111 sig_wait(SIG_ADC_COMPLETE);
113 //Wait in polling until is done
114 while (ADCSRA & BV(ADSC)) ;
123 INLINE void adc_hw_init(void)
126 * Select channel 0 as default,
127 * result right adjusted.
131 #if CONFIG_ADC_AVR_REF == ADC_AVR_AREF
132 /* External voltage at AREF as analog ref source */
134 #elif CONFIG_ADC_AVR_REF == ADC_AVR_AVCC
135 /* AVCC as analog ref source */
137 #elif CONFIG_ADC_AVR_REF == ADC_AVR_INT256
138 /* Internal 2.56V as ref source */
139 ADMUX |= BV(REFS1) | BV(REFS0);
141 #error Unsupported ADC ref value.
144 /* Disable Auto trigger source: ADC in Free running mode. */
147 /* Enable ADC, disable autotrigger mode. */
155 /* Set convertion frequency */
156 #if CONFIG_ADC_AVR_DIVISOR == 2
158 #elif CONFIG_ADC_AVR_DIVISOR == 4
160 #elif CONFIG_ADC_AVR_DIVISOR == 8
161 ADCSRA |= BV(ADPS1) | BV(ADPS0);
162 #elif CONFIG_ADC_AVR_DIVISOR == 16
164 #elif CONFIG_ADC_AVR_DIVISOR == 32
165 ADCSRA |= BV(ADPS2) | BV(ADPS0);
166 #elif CONFIG_ADC_AVR_DIVISOR == 64
167 ADCSRA |= BV(ADPS2) | BV(ADPS1);
168 #elif CONFIG_ADC_AVR_DIVISOR == 128
169 ADCSRA |= BV(ADPS2) | BV(ADPS1) | BV(ADPS0);
171 #error Unsupported ADC prescaler value.
174 /* Start a convertion to init ADC hw */