3 * Erik Theisen, Wave 7 Optics, etheisen@mindspring.com.
5 * See file CREDITS for list of people who contributed to this
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
25 * Dallas Semiconductor's DS1621 Digital Thermometer and Thermostat.
35 #define DTT_I2C_DEV_CODE 0x48 /* Dallas Semi's DS1621 */
36 #define DTT_READ_TEMP 0xAA
37 #define DTT_READ_COUNTER 0xA8
38 #define DTT_READ_SLOPE 0xA9
39 #define DTT_WRITE_START_CONV 0xEE
40 #define DTT_WRITE_STOP_CONV 0x22
41 #define DTT_TEMP_HIGH 0xA1
42 #define DTT_TEMP_LOW 0xA2
43 #define DTT_CONFIG 0xAC
45 int dtt_read(int sensor
, int reg
)
51 * Calculate sensor address and command.
54 sensor
= DTT_I2C_DEV_CODE
+ (sensor
& 0x07); /* Calculate addr of ds1621*/
57 * Prepare to handle 2 byte result.
59 if ((reg
== DTT_READ_TEMP
) ||
60 (reg
== DTT_TEMP_HIGH
) || (reg
== DTT_TEMP_LOW
))
66 * Now try to read the register.
68 if (i2c_read(sensor
, reg
, 1, data
, dlen
) != 0)
72 * Handle 2 byte result.
75 return ((int)((short)data
[1] + (((short)data
[0]) << 8)));
81 int dtt_write(int sensor
, int reg
, int val
)
87 * Calculate sensor address and register.
90 sensor
= DTT_I2C_DEV_CODE
+ (sensor
& 0x07);
93 * Handle various data sizes.
95 if ((reg
== DTT_READ_TEMP
) ||
96 (reg
== DTT_TEMP_HIGH
) || (reg
== DTT_TEMP_LOW
)) {
98 data
[0] = (char)((val
>> 8) & 0xff); /* MSB first */
99 data
[1] = (char)(val
& 0xff);
101 else if ((reg
== DTT_WRITE_START_CONV
) || (reg
== DTT_WRITE_STOP_CONV
)) {
108 data
[0] = (char)(val
& 0xff);
112 * Write value to device.
114 if (i2c_write(sensor
, reg
, 1, data
, dlen
) != 0)
121 static int _dtt_init(int sensor
)
128 val
= ((CONFIG_SYS_DTT_MAX_TEMP
* 2) << 7) & 0xff80;
129 if (dtt_write(sensor
, DTT_TEMP_HIGH
, val
) != 0)
131 udelay(50000); /* Max 50ms */
134 * Setup Low Temp - hysteresis.
136 val
= (((CONFIG_SYS_DTT_MAX_TEMP
- CONFIG_SYS_DTT_HYSTERESIS
) * 2) << 7) & 0xff80;
137 if (dtt_write(sensor
, DTT_TEMP_LOW
, val
) != 0)
139 udelay(50000); /* Max 50ms */
142 * Setup configuraton register
144 * Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
146 * We run in polled mode, since there isn't any way to know if this
147 * lousy device is ready to provide temperature readings on power up.
150 if (dtt_write(sensor
, DTT_CONFIG
, val
) != 0)
152 udelay(50000); /* Max 50ms */
161 unsigned char sensors
[] = CONFIG_DTT_SENSORS
;
163 for (i
= 0; i
< sizeof(sensors
); i
++) {
164 if (_dtt_init(sensors
[i
]) != 0)
165 printf("DTT%d: FAILED\n", i
+1);
167 printf("DTT%d: %i C\n", i
+1, dtt_get_temp(sensors
[i
]));
174 int dtt_get_temp(int sensor
)
179 * Start a conversion, may take up to 1 second.
181 dtt_write(sensor
, DTT_WRITE_START_CONV
, 0);
182 for (i
= 0; i
<= 10; i
++) {
184 if (dtt_read(sensor
, DTT_CONFIG
) & 0x80)
188 return (dtt_read(sensor
, DTT_READ_TEMP
) / 256);
189 } /* dtt_get_temp() */