4 * This file is part of BeRTOS.
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7 * it under the terms of the GNU General Public License as published by
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13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
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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
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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
46 #include "cfg/cfg_adc.h"
47 #include "cfg/cfg_proc.h"
48 #include "cfg/cfg_signal.h"
49 #include <cfg/macros.h>
50 #include <cfg/compiler.h>
52 #include <cpu/irq.h> // IRQ_ASSERT_ENABLED()
57 #include <avr/interrupt.h>
60 * ADC voltage referencese.
62 * $WIZ$ avr_adc_refs = "ADC_AVR_AREF", "ADC_AVR_AVCC", "ADC_AVR_INT256"
65 #define ADC_AVR_AREF 0
66 #define ADC_AVR_AVCC 1
67 #define ADC_AVR_INT256 2
71 #include <cfg/module.h>
72 #include <kern/proc.h>
73 #include <kern/signal.h>
76 #if !CONFIG_KERN_SIGNALS
77 #error Signals must be active to use the ADC with kernel
80 /* Signal adc convertion end */
81 #define SIG_ADC_COMPLETE SIG_SINGLE
83 /* ADC waiting process */
84 static struct Process *adc_process;
88 * Simply signal the adc process that convertion is complete.
92 sig_signal(adc_process, SIG_ADC_COMPLETE);
94 #endif /* CONFIG_KERN */
97 * Select mux channel \a ch.
98 * \todo only first 8 channels are selectable!
100 void adc_hw_select_ch(uint8_t ch)
102 /* Set to 0 all mux registers */
103 ADMUX &= ~(BV(MUX4) | BV(MUX3) | BV(MUX2) | BV(MUX1) | BV(MUX0));
105 /* Select channel, only first 8 channel modes are supported for now */
106 ADMUX |= (ch & 0x07);
111 * Start an ADC convertion.
112 * If a kernel is present, preempt until convertion is complete, otherwise
113 * a busy wait on ADCS bit is done.
115 uint16_t adc_hw_read(void)
117 // Ensure another convertion is not running.
118 ASSERT(!(ADCSRA & BV(ADSC)));
124 // Ensure IRQs enabled.
125 IRQ_ASSERT_ENABLED();
126 adc_process = proc_current();
127 sig_wait(SIG_ADC_COMPLETE);
129 //Wait in polling until is done
130 while (ADCSRA & BV(ADSC)) ;
139 void adc_hw_init(void)
142 * Select channel 0 as default,
143 * result right adjusted.
147 #if CONFIG_ADC_AVR_REF == ADC_AVR_AREF
148 /* External voltage at AREF as analog ref source */
150 #elif CONFIG_ADC_AVR_REF == ADC_AVR_AVCC
151 /* AVCC as analog ref source */
153 #elif CONFIG_ADC_AVR_REF == ADC_AVR_INT256
154 /* Internal 2.56V as ref source */
155 ADMUX |= BV(REFS1) | BV(REFS0);
157 #error Unsupported ADC ref value.
161 /* Disable Auto trigger source: ADC in Free running mode. */
165 /* Enable ADC, disable autotrigger mode. */
173 /* Set convertion frequency */
174 #if CONFIG_ADC_AVR_DIVISOR == 2
176 #elif CONFIG_ADC_AVR_DIVISOR == 4
178 #elif CONFIG_ADC_AVR_DIVISOR == 8
179 ADCSRA |= BV(ADPS1) | BV(ADPS0);
180 #elif CONFIG_ADC_AVR_DIVISOR == 16
182 #elif CONFIG_ADC_AVR_DIVISOR == 32
183 ADCSRA |= BV(ADPS2) | BV(ADPS0);
184 #elif CONFIG_ADC_AVR_DIVISOR == 64
185 ADCSRA |= BV(ADPS2) | BV(ADPS1);
186 #elif CONFIG_ADC_AVR_DIVISOR == 128
187 ADCSRA |= BV(ADPS2) | BV(ADPS1) | BV(ADPS0);
189 #error Unsupported ADC prescaler value.
192 /* Start a convertion to init ADC hw */