Added blocking ADC driver for AVR to complement the non-blocking driver.

2011-01-26 16:28:23 +00:00
parent 3f22c7e5ff
commit 6b83f182a7
1 changed files with 130 additions and 0 deletions
@@ -0,0 +1,130 @@
+/**************************************************************************
+*
+* Copyright (C) 2009 Steve Karg <skarg@users.sourceforge.net>
+*
+* Permission is hereby granted, free of charge, to any person obtaining
+* a copy of this software and associated documentation files (the
+* "Software"), to deal in the Software without restriction, including
+* without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to
+* permit persons to whom the Software is furnished to do so, subject to
+* the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*********************************************************************/
+#include <stdbool.h>
+#include <stdint.h>
+#include "hardware.h"
+/* me */
+#include "adc.h"
+
+/* prescale select bits */
+#if   (F_CPU >> 1) < 1000000
+#define ADPS_8BIT    (1)
+#define ADPS_10BIT   (3)
+#elif (F_CPU >> 2) < 1000000
+#define ADPS_8BIT    (2)
+#define ADPS_10BIT   (4)
+#elif (F_CPU >> 3) < 1000000
+#define ADPS_8BIT    (3)
+#define ADPS_10BIT   (5)
+#elif (F_CPU >> 4) < 1000000
+#define ADPS_8BIT    (4)
+#define ADPS_10BIT   (6)
+#elif (F_CPU >> 5) < 1000000
+#define ADPS_8BIT    (5)
+#define ADPS_10BIT   (7)
+#else
+#error  "ADC: F_CPU too large for accuracy."
+#endif
+
+/* ADMUX: channel bits 0..4
+      ADLAR = Left Adjust Result
+      REFSx = hardware setup: cap on AREF
+*/
+/* ADCSRA:
+      ADEN = Enable
+      ADSC = Start conversion
+      ADIF = Interrupt Flag
+      ADIE = Interrupt Enable
+      ADATE = Auto Trigger Enable
+*/
+
+void adc_enable(
+    uint8_t index)
+{
+    index = index;
+    /* do nothing */
+}
+
+/**************************************************
+* Description: Run a Analog to Digital conversion
+* Returns: none
+* Notes: none
+**************************************************/
+uint8_t adc_result_8bit(
+    uint8_t channel) /* 0..7 = ADC0..ADC7, respectively */
+{
+    uint8_t value = 0; /* return value */
+
+    while ( ADCSRA & (1 << ADSC) ) ;
+    ADMUX = channel | (1 << ADLAR) | (0 << REFS1) | (1 << REFS0);
+    /* Delay needed for the stabilization of the ADC input voltage */
+    _delay_us(10);
+    /* Start the analog to digital conversion */
+    ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADIF) | ADPS_8BIT;
+    /* Wait for the analog to digital conversion to complete */
+    while ( (ADCSRA & (1 << ADIF)) == 0 ) ;
+    value = ADCH;
+
+    return value;
+}
+
+/**************************************************
+* Description: Run a Analog to Digital conversion
+* Returns: none
+* Notes: none
+**************************************************/
+uint16_t adc_result_10bit(
+    uint8_t channel) /* 0..7 = ADC0..ADC7, respectively */
+{
+    uint16_t value = 0; /* return value */
+
+    while ( ADCSRA & (1 << ADSC) ) ;
+    ADMUX = channel | (0 << ADLAR) | (0 << REFS1) | (1 << REFS0);
+    /* Delay needed for the stabilization of the ADC input voltage */
+    _delay_us(10);
+    /* Start the analog to digital conversion */
+    ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADIF) | ADPS_10BIT;
+    /* Wait for the analog to digital conversion to complete */
+    while ( (ADCSRA & (1 << ADIF)) == 0 ) ;
+    value = ADCL;
+    value |= (ADCH << 8);
+
+    return value;
+}
+
+/**************************************************
+* Description: Initializes the Analog to Digital Converter
+* Returns: none
+* Notes: none
+**************************************************/
+void adc_init(void)
+{
+    /* configure ADC for Free Running Mode - ADTS = 000 */
+    /* AIN1 is applied to the negative input of the Analog Comparator - ACME */
+    BITMASK_CLEAR(ADCSRB, _BV(ACME)|_BV(ADTS2)|_BV(ADTS1)|_BV(ADTS0));
+    /* Digital input not needed on ADC0, so disable it to save power */
+    BIT_SET(DIDR0, ADC0D);
+    /* Clear the Power Reduction bit to enable ADC */
+    BIT_CLEAR(PRR, PRADC);
+}