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Diffstat (limited to 'firmware/target/arm/sandisk/sansa-e200/adc-e200.c')
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diff --git a/firmware/target/arm/sandisk/sansa-e200/adc-e200.c b/firmware/target/arm/sandisk/sansa-e200/adc-e200.c
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1/***************************************************************************
2 * __________ __ ___.
3 * Open \______ \ ____ ____ | | _\_ |__ _______ ___
4 * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
5 * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
6 * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
7 * \/ \/ \/ \/ \/
8 * $Id$
9 *
10 * Copyright (C) 2006 by Barry Wardell
11 *
12 * All files in this archive are subject to the GNU General Public License.
13 * See the file COPYING in the source tree root for full license agreement.
14 *
15 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
16 * KIND, either express or implied.
17 *
18 ****************************************************************************/
19#include "config.h"
20#include "cpu.h"
21#include "system.h"
22#include "kernel.h"
23#include "thread.h"
24#include "adc.h"
25
26static unsigned short adcdata[NUM_ADC_CHANNELS];
27
28/* Scan ADC so that adcdata[channel] gets updated */
29unsigned short adc_scan(int channel)
30{
31 unsigned int adc_data_1;
32 unsigned int adc_data_2;
33
34 /* Initialise */
35 ADC_ADDR=0x130;
36 ADC_STATUS=0; /* 4 bytes, 1 per channel. Each byte is 0 if the channel is
37 off, 0x40 if the channel is on */
38
39 /* Enable Channel */
40 ADC_ADDR |= (0x1000000<<channel);
41
42 /* Start? */
43 ADC_ADDR |= 0x20000000;
44 ADC_ADDR |= 0x80000000;
45
46 /* ADC_DATA_1 and ADC_DATA_2 are both four bytes, one byte per channel.
47 For each channel, ADC_DATA_1 stores the 8-bit msb, ADC_DATA_2 stores the
48 2-bit lsb (in bits 0 and 1). Each channel is 10 bits total. */
49 adc_data_1 = ((ADC_DATA_1 >> (8*channel)) & 0xff);
50 adc_data_2 = ((ADC_DATA_2 >> (8*channel+6)) & 0x3);
51
52 adcdata[channel] = (adc_data_1<<2 | adc_data_2);
53
54 return adcdata[channel];
55}
56
57/* Read 10-bit channel data */
58unsigned short adc_read(int channel)
59{
60 return adcdata[channel];
61}
62
63static int adc_counter;
64
65static void adc_tick(void)
66{
67 if(++adc_counter == HZ)
68 {
69 adc_counter = 0;
70 adc_scan(ADC_0);
71 adc_scan(ADC_1);
72 adc_scan(ADC_2);
73 adc_scan(ADC_3);
74 }
75}
76
77void adc_init(void)
78{
79 /* Enable ADC */
80 ADC_ENABLE_ADDR |= ADC_ENABLE;
81
82 /* Initialise */
83 ADC_INIT=0;
84
85 /* Force a scan of all channels to get initial values */
86 adc_scan(ADC_0);
87 adc_scan(ADC_1);
88 adc_scan(ADC_2);
89 adc_scan(ADC_3);
90
91 tick_add_task(adc_tick);
92}