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/*
* (C) Copyright 2001
* Erik Theisen, Wave 7 Optics, etheisen@mindspring.com.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/*
* Dallas Semiconductor's DS1621 Digital Thermometer and Thermostat.
*/
#include <common.h>
#include <i2c.h>
#include <dtt.h>
/*
* Device code
*/
#define DTT_I2C_DEV_CODE 0x48 /* Dallas Semi's DS1621 */
#define DTT_READ_TEMP 0xAA
#define DTT_READ_COUNTER 0xA8
#define DTT_READ_SLOPE 0xA9
#define DTT_WRITE_START_CONV 0xEE
#define DTT_WRITE_STOP_CONV 0x22
#define DTT_TEMP_HIGH 0xA1
#define DTT_TEMP_LOW 0xA2
#define DTT_CONFIG 0xAC
int dtt_read(int sensor, int reg)
{
int dlen;
uchar data[2];
/*
* Calculate sensor address and command.
*
*/
sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1621*/
/*
* Prepare to handle 2 byte result.
*/
if ((reg == DTT_READ_TEMP) ||
(reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW))
dlen = 2;
else
dlen = 1;
/*
* Now try to read the register.
*/
if (i2c_read(sensor, reg, 1, data, dlen) != 0)
return 1;
/*
* Handle 2 byte result.
*/
if (dlen == 2)
return ((int)((short)data[1] + (((short)data[0]) << 8)));
return (int)data[0];
} /* dtt_read() */
int dtt_write(int sensor, int reg, int val)
{
int dlen;
uchar data[2];
/*
* Calculate sensor address and register.
*
*/
sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
/*
* Handle various data sizes.
*/
if ((reg == DTT_READ_TEMP) ||
(reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW)) {
dlen = 2;
data[0] = (char)((val >> 8) & 0xff); /* MSB first */
data[1] = (char)(val & 0xff);
}
else if ((reg == DTT_WRITE_START_CONV) || (reg == DTT_WRITE_STOP_CONV)) {
dlen = 0;
data[0] = (char)0;
data[1] = (char)0;
}
else {
dlen = 1;
data[0] = (char)(val & 0xff);
}
/*
* Write value to device.
*/
if (i2c_write(sensor, reg, 1, data, dlen) != 0)
return 1;
return 0;
} /* dtt_write() */
static int _dtt_init(int sensor)
{
int val;
/*
* Setup High Temp.
*/
val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0)
return 1;
udelay(50000); /* Max 50ms */
/*
* Setup Low Temp - hysteresis.
*/
val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0)
return 1;
udelay(50000); /* Max 50ms */
/*
* Setup configuraton register
*
* Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
*
* We run in polled mode, since there isn't any way to know if this
* lousy device is ready to provide temperature readings on power up.
*/
val = 0x9;
if (dtt_write(sensor, DTT_CONFIG, val) != 0)
return 1;
udelay(50000); /* Max 50ms */
return 0;
} /* _dtt_init() */
int dtt_init (void)
{
int i;
unsigned char sensors[] = CONFIG_DTT_SENSORS;
for (i = 0; i < sizeof(sensors); i++) {
if (_dtt_init(sensors[i]) != 0)
printf("DTT%d: FAILED\n", i+1);
else
printf("DTT%d: %i C\n", i+1, dtt_get_temp(sensors[i]));
}
return (0);
} /* dtt_init() */
int dtt_get_temp(int sensor)
{
int i;
/*
* Start a conversion, may take up to 1 second.
*/
dtt_write(sensor, DTT_WRITE_START_CONV, 0);
for (i = 0; i <= 10; i++) {
udelay(100000);
if (dtt_read(sensor, DTT_CONFIG) & 0x80)
break;
}
return (dtt_read(sensor, DTT_READ_TEMP) / 256);
} /* dtt_get_temp() */
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