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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2006 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 "cpu.h"
#include "system.h"
#include "kernel.h"
#include "thread.h"
#include "adc.h"
#define CS_LO and_l(~0x80, &GPIO_OUT)
#define CS_HI or_l(0x80, &GPIO_OUT)
#define CLK_LO and_l(~0x00400000, &GPIO_OUT)
#define CLK_HI or_l(0x00400000, &GPIO_OUT)
#define DO (GPIO_READ & 0x80000000)
#define DI_LO and_l(~0x00200000, &GPIO_OUT)
#define DI_HI or_l(0x00200000, &GPIO_OUT)
/* delay loop */
#define DELAY \
({ \
int _x_; \
asm volatile ( \
"move.l #11, %[_x_] \r\n" \
"1: \r\n" \
"subq.l #1, %[_x_] \r\n" \
"bhi.b 1b \r\n" \
: [_x_]"=&d"(_x_) \
); \
})
unsigned short adc_scan(int channel)
{
int level = set_irq_level(HIGHEST_IRQ_LEVEL);
unsigned char data = 0;
int i;
CS_LO;
DI_HI; /* Start bit */
DELAY;
CLK_HI;
DELAY;
CLK_LO;
DI_HI; /* Single channel */
DELAY;
CLK_HI;
DELAY;
CLK_LO;
if(channel & 1) /* LSB of channel number */
DI_HI;
else
DI_LO;
DELAY;
CLK_HI;
DELAY;
CLK_LO;
if(channel & 2) /* MSB of channel number */
DI_HI;
else
DI_LO;
DELAY;
CLK_HI;
DELAY;
CLK_LO;
DELAY;
for(i = 0;i < 8;i++) /* 8 bits of data */
{
CLK_HI;
DELAY;
CLK_LO;
DELAY;
data <<= 1;
data |= DO?1:0;
}
CS_HI;
set_irq_level(level);
return data;
}
void adc_init(void)
{
or_l(0x80600080, &GPIO_FUNCTION); /* GPIO7: CS
GPIO21: Data In (to the ADC)
GPIO22: CLK
GPIO31: Data Out (from the ADC) */
or_l(0x00600080, &GPIO_ENABLE);
or_l(0x80, &GPIO_OUT); /* CS high */
and_l(~0x00400000, &GPIO_OUT); /* CLK low */
}
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