Contiki port for the Atmel AVR Raven board

platform/avr-ravenlcd/adc.c

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+/*
+ *  Copyright (c) 2008  Swedish Institute of Computer Science
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *  * Neither the name of the copyright holders nor the names of
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+/**
+ * \file
+ *
+ * \brief
+ *      Functions to control the ADC of the MCU. This is used to read the
+ *      joystick.
+ *
+ * \author
+ *      Mike Vidales mavida404@gmail.com
+ *
+ */
+
+#include "adc.h"
+
+/**
+ *  \addtogroup lcd
+ *  \{
+*/
+
+static bool adc_initialized;
+static bool adc_conversion_started;
+
+/*---------------------------------------------------------------------------*/
+
+/**
+ *   \brief This function will init the ADC with the following parameters.
+ *
+ *   \param chan Determines the ADC channel to open.
+ *   \param trig Sets what type of trigger is needed.
+ *   \param ref Sets the proper reference voltage.
+ *   \param prescale Sets the prescale to be used against the XTAL choice.
+ *
+ *   \return 0
+*/
+int
+adc_init(adc_chan_t chan, adc_trig_t trig, adc_ref_t ref, adc_ps_t prescale)
+{
+    /* Enable ADC module */
+    PRR &= ~(1 << PRADC);
+
+    /* Configure */
+    ADCSRA = (1<<ADEN)|prescale;
+    ADMUX = (uint8_t)ref|(uint8_t)chan;
+    ADCSRB = trig;
+
+    adc_initialized = true;
+    adc_conversion_started = false;
+
+    return 0;
+}
+
+/*---------------------------------------------------------------------------*/
+
+/**
+ *   \brief This will disable the adc.
+*/
+void
+adc_deinit(void)
+{
+    /* Disable ADC */
+    ADCSRA &= ~(1<<ADEN);
+    PRR |= (1 << PRADC);
+
+    adc_initialized = false;
+    adc_conversion_started = false;
+}
+
+/*---------------------------------------------------------------------------*/
+
+/**
+ *   \brief This will start an ADC conversion
+ *
+ *   \return 0
+*/
+int
+adc_conversion_start(void)
+{
+    if (adc_initialized == false){
+        return EOF;
+    }
+    adc_conversion_started = true;
+    ADCSRA |= (1<<ADSC);
+    return 0;
+}
+
+/*---------------------------------------------------------------------------*/
+
+/**
+ *   \brief This will read the ADC result during the ADC conversion and return
+ *   the raw ADC conversion result.
+ *
+ *   \param adjust This will Left or Right Adjust the ADC conversion result.
+ *
+ *   \return ADC raw 16-byte ADC conversion result.
+*/
+int16_t
+adc_result_get(adc_adj_t adjust)
+{
+    if (adc_conversion_started == false){
+        return EOF;
+    }
+    if (ADCSRA & (1<<ADSC)){
+        return EOF;
+    }
+    adc_conversion_started = false;
+    ADMUX |= (adjust<<ADLAR);
+    return (int16_t)ADC;
+}
+
+/** \}   */