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>
37 * This module is automatically included so no need to include
44 #include <cpu/irq.h> // IRQ_ASSERT_ENABLED()
45 #include "cfg/cfg_adc.h"
46 #include "cfg/cfg_kern.h"
47 #include <cfg/macros.h>
48 #include <cfg/compiler.h>
53 #include <avr/interrupt.h>
55 #define ADC_AVR_AREF 0
56 #define ADC_AVR_AVCC 1
57 #define ADC_AVR_INT256 2
60 #include <cfg/module.h>
61 #include <kern/proc.h>
62 #include <kern/signal.h>
65 #if !CONFIG_KERN_SIGNALS
66 #error Signals must be active to use ADC with kernel
69 /* Signal adc convertion end */
70 #define SIG_ADC_COMPLETE SIG_SINGLE
72 /* ADC waiting process */
73 static struct Process *adc_process;
77 * Simply signal the adc process that convertion is complete.
81 sig_signal(adc_process, SIG_ADC_COMPLETE);
83 #endif /* CONFIG_KERN */
86 * Select mux channel \a ch.
87 * \todo only first 8 channels are selectable!
89 INLINE void adc_hw_select_ch(uint8_t ch)
91 /* Set to 0 all mux registers */
92 ADMUX &= ~(BV(MUX3) | BV(MUX3) | BV(MUX2) | BV(MUX1) | BV(MUX0));
94 /* Select channel, only first 8 channel modes are supported for now */
100 * Start an ADC convertion.
101 * If a kernel is present, preempt until convertion is complete, otherwise
102 * a busy wait on ADCS bit is done.
104 INLINE uint16_t adc_hw_read(void)
106 // Ensure another convertion is not running.
107 ASSERT(!(ADCSRA & BV(ADSC)));
113 // Ensure IRQs enabled.
114 IRQ_ASSERT_ENABLED();
115 adc_process = proc_current();
116 sig_wait(SIG_ADC_COMPLETE);
118 //Wait in polling until is done
119 while (ADCSRA & BV(ADSC)) ;
128 INLINE void adc_hw_init(void)
131 * Select channel 0 as default,
132 * result right adjusted.
136 #if CONFIG_ADC_AVR_REF == ADC_AVR_AREF
137 /* External voltage at AREF as analog ref source */
139 #elif CONFIG_ADC_AVR_REF == ADC_AVR_AVCC
140 /* AVCC as analog ref source */
142 #elif CONFIG_ADC_AVR_REF == ADC_AVR_INT256
143 /* Internal 2.56V as ref source */
144 ADMUX |= BV(REFS1) | BV(REFS0);
146 #error Unsupported ADC ref value.
149 /* Disable Auto trigger source: ADC in Free running mode. */
152 /* Enable ADC, disable autotrigger mode. */
160 /* Set convertion frequency */
161 #if CONFIG_ADC_AVR_DIVISOR == 2
163 #elif CONFIG_ADC_AVR_DIVISOR == 4
165 #elif CONFIG_ADC_AVR_DIVISOR == 8
166 ADCSRA |= BV(ADPS1) | BV(ADPS0);
167 #elif CONFIG_ADC_AVR_DIVISOR == 16
169 #elif CONFIG_ADC_AVR_DIVISOR == 32
170 ADCSRA |= BV(ADPS2) | BV(ADPS0);
171 #elif CONFIG_ADC_AVR_DIVISOR == 64
172 ADCSRA |= BV(ADPS2) | BV(ADPS1);
173 #elif CONFIG_ADC_AVR_DIVISOR == 128
174 ADCSRA |= BV(ADPS2) | BV(ADPS1) | BV(ADPS0);
176 #error Unsupported ADC prescaler value.
179 /* Start a convertion to init ADC hw */