b627106392
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26138 a1c6a512-1295-4272-9138-f99709370657
94 lines
2.6 KiB
C
94 lines
2.6 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id:$
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*
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* Copyright (C) 2010 Marcin Bukat
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "config.h"
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#include "cpu.h"
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#include "system.h"
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#include "kernel.h"
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#include "thread.h"
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#include "adc.h"
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volatile unsigned short adc_data[NUM_ADC_CHANNELS] IBSS_ATTR;
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/* Reading takes 4096 adclk ticks
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* 1) tick task is created that enables ADC interrupt
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* 2) On interrupt single channel is readed and
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* ADC is prepared for next channel
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* 3) When all 4 channels are scanned ADC interrupt is disabled
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*/
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void ADC(void) __attribute__ ((interrupt_handler,section(".icode")));
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void ADC(void)
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{
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static unsigned char channel IBSS_ATTR;
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/* read current value */
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adc_data[(channel & 0x03)] = ADVALUE;
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/* switch channel
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*
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* set source remark
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* ADCONFIG is 16bit wide so we have to shift data by 16bits left
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* thats why we shift <<24 instead of <<8
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*/
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channel++;
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and_l(~(3<<24),&ADCONFIG);
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or_l( (((channel & 0x03) << 8 )|(1<<7))<<16, &ADCONFIG);
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if ( (channel & 0x03) == 0 )
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/* disable ADC interrupt */
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and_l((~(1<<6))<<16,&ADCONFIG);
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}
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unsigned short adc_scan(int channel)
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{
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/* maybe we can drop &0x03 part */
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return adc_data[(channel&0x03)];
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}
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void adc_tick(void)
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{
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/* enable ADC interrupt */
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or_l( ((1<<6))<<16, &ADCONFIG);
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}
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void adc_init(void)
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{
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/* GPIO38 GPIO39 */
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and_l(~((1<<6)|(1<<7)), &GPIO1_FUNCTION);
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/* ADOUT_SEL = 01
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* SOURCE SELECT = 000
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* CLEAR INTERRUPT FLAG
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* ENABLE INTERRUPT = 0
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* ADOUT_DRIVE = 00
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* ADCLK_SEL = 011 (busclk/8)
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*/
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ADCONFIG = (1<<10)|(1<<7)|(1<<1)|(1<<0);
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/* ADC interrupt level 4.0 */
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or_l((4<<28), &INTPRI8);
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/* create tick task which enables ADC interrupt */
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tick_add_task(adc_tick);
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}
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