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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2002 by Linus Nielsen Feltzing
*
* All files in this archive are subject to the GNU General Public License.
* See the file COPYING in the source tree root for full license agreement.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include "sh7034.h"
#include "kernel.h"
#include "thread.h"
#include "adc.h"
static int current_channel;
static unsigned short adcdata[NUM_ADC_CHANNELS];
static unsigned int adcreg[NUM_ADC_CHANNELS] =
{
ADDRAH_ADDR, ADDRBH_ADDR, ADDRCH_ADDR, ADDRDH_ADDR,
ADDRAH_ADDR, ADDRBH_ADDR, ADDRCH_ADDR, ADDRDH_ADDR
};
static void adc_tick(void)
{
/* Read the data that has bee converted since the last tick */
adcdata[current_channel] =
*(unsigned short *)adcreg[current_channel] >> 6;
/* Start a conversion on the next channel */
current_channel++;
if(current_channel == NUM_ADC_CHANNELS)
current_channel = 0;
ADCSR = ADCSR_ADST | current_channel;
}
unsigned short adc_read(int channel)
{
return adcdata[channel];
}
/* Batch convert 4 analog channels. If lower is true, convert AN0-AN3,
* otherwise AN4-AN7.
*/
static void adc_batch_convert(bool lower)
{
int reg = lower ? 0 : 4;
volatile unsigned short* ANx = ((unsigned short*) ADDRAH_ADDR);
int i;
ADCSR = ADCSR_ADST | ADCSR_SCAN | ADCSR_CKS | reg | 3;
/* Busy wait until conversion is complete. A bit ugly perhaps, but
* we should only need to wait about 4 * 14 µs */
while(!(ADCSR & ADCSR_ADF))
{
}
/* Stop scanning */
ADCSR = 0;
for (i = 0; i < 4; i++)
{
/* Read converted values */
adcdata[reg++] = ANx[i] >> 6;
}
}
void adc_init(void)
{
ADCR = 0x7f; /* No external trigger; other bits should be 1 according to the manual... */
current_channel = 0;
/* Do a first scan to initialize all values */
/* AN4 to AN7 */
adc_batch_convert(false);
/* AN0 to AN3 */
adc_batch_convert(true);
tick_add_task(adc_tick);
}
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