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Diffstat (limited to 'Documentation/w1/slaves/w1_therm')
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diff --git a/Documentation/w1/slaves/w1_therm b/Documentation/w1/slaves/w1_therm deleted file mode 100644 index d1f93af36f38..000000000000 --- a/Documentation/w1/slaves/w1_therm +++ /dev/null @@ -1,67 +0,0 @@ -Kernel driver w1_therm -==================== - -Supported chips: - * Maxim ds18*20 based temperature sensors. - * Maxim ds1825 based temperature sensors. - -Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru> - - -Description ------------ - -w1_therm provides basic temperature conversion for ds18*20 devices, and the -ds28ea00 device. -supported family codes: -W1_THERM_DS18S20 0x10 -W1_THERM_DS1822 0x22 -W1_THERM_DS18B20 0x28 -W1_THERM_DS1825 0x3B -W1_THERM_DS28EA00 0x42 - -Support is provided through the sysfs w1_slave file. Each open and -read sequence will initiate a temperature conversion then provide two -lines of ASCII output. The first line contains the nine hex bytes -read along with a calculated crc value and YES or NO if it matched. -If the crc matched the returned values are retained. The second line -displays the retained values along with a temperature in millidegrees -Centigrade after t=. - -Parasite powered devices are limited to one slave performing a -temperature conversion at a time. If none of the devices are parasite -powered it would be possible to convert all the devices at the same -time and then go back to read individual sensors. That isn't -currently supported. The driver also doesn't support reduced -precision (which would also reduce the conversion time) when reading values. - -Writing a value between 9 and 12 to the sysfs w1_slave file will change the -precision of the sensor for the next readings. This value is in (volatile) -SRAM, so it is reset when the sensor gets power-cycled. - -To store the current precision configuration into EEPROM, the value 0 -has to be written to the sysfs w1_slave file. Since the EEPROM has a limited -amount of writes (>50k), this command should be used wisely. - -The module parameter strong_pullup can be set to 0 to disable the -strong pullup, 1 to enable autodetection or 2 to force strong pullup. -In case of autodetection, the driver will use the "READ POWER SUPPLY" -command to check if there are pariste powered devices on the bus. -If so, it will activate the master's strong pullup. -In case the detection of parasite devices using this command fails -(seems to be the case with some DS18S20) the strong pullup can -be force-enabled. -If the strong pullup is enabled, the master's strong pullup will be -driven when the conversion is taking place, provided the master driver -does support the strong pullup (or it falls back to a pullup -resistor). The DS18b20 temperature sensor specification lists a -maximum current draw of 1.5mA and that a 5k pullup resistor is not -sufficient. The strong pullup is designed to provide the additional -current required. - -The DS28EA00 provides an additional two pins for implementing a sequence -detection algorithm. This feature allows you to determine the physical -location of the chip in the 1-wire bus without needing pre-existing -knowledge of the bus ordering. Support is provided through the sysfs -w1_seq file. The file will contain a single line with an integer value -representing the device index in the bus starting at 0. |