26f42605c2
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4260 a1c6a512-1295-4272-9138-f99709370657
91 lines
2.6 KiB
C
91 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) 2002 by Linus Nielsen Feltzing
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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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 "sh7034.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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static int current_channel;
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static unsigned short adcdata[NUM_ADC_CHANNELS];
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static unsigned int adcreg[NUM_ADC_CHANNELS] =
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{
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ADDRAH_ADDR, ADDRBH_ADDR, ADDRCH_ADDR, ADDRDH_ADDR,
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ADDRAH_ADDR, ADDRBH_ADDR, ADDRCH_ADDR, ADDRDH_ADDR
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};
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static void adc_tick(void)
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{
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/* Read the data that has bee converted since the last tick */
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adcdata[current_channel] =
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*(unsigned short *)adcreg[current_channel] >> 6;
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/* Start a conversion on the next channel */
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current_channel++;
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if(current_channel == NUM_ADC_CHANNELS)
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current_channel = 0;
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ADCSR = ADCSR_ADST | current_channel;
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}
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unsigned short adc_read(int channel)
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{
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return adcdata[channel];
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}
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/* Batch convert 4 analog channels. If lower is true, convert AN0-AN3,
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* otherwise AN4-AN7.
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*/
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static void adc_batch_convert(bool lower)
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{
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int reg = lower ? 0 : 4;
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volatile unsigned short* ANx = ((unsigned short*) ADDRAH_ADDR);
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int i;
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ADCSR = ADCSR_ADST | ADCSR_SCAN | reg | 3;
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/* Busy wait until conversion is complete. A bit ugly perhaps, but
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* we should only need to wait about 4 * 14 <20>s */
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while(!(ADCSR & ADCSR_ADF))
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{
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}
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/* Stop scanning */
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ADCSR = 0;
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for (i = 0; i < 4; i++)
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{
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/* Read converted values */
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adcdata[reg++] = ANx[i] >> 6;
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}
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}
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void adc_init(void)
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{
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ADCR = 0x7f; /* No external trigger; other bits should be 1 according to the manual... */
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current_channel = 0;
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/* Do a first scan to initialize all values */
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/* AN4 to AN7 */
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adc_batch_convert(false);
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/* AN0 to AN3 */
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adc_batch_convert(true);
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tick_add_task(adc_tick);
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}
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