Messages in this thread Patch in this message | | | Date | Fri, 28 Mar 2008 07:25:15 -0500 | From | David Fries <> | Subject | [PATCH 9/35] W1: create documentation for the w1_therm slave device |
| |
New directory for temperature sensor documentation.
Documentation/w1/00-INDEX 1.2 Added new subdirectory slaves
Documentation/w1/slaves/00-INDEX 1.1 1.2 Added index and w1_therm entry.
Documentation/w1/slaves/w1_therm 1.1 1.2 Initial entry for the temperature sensor.
Signed-off-by: David Fries <david@fries.net> --- Documentation/w1/00-INDEX | 2 ++ Documentation/w1/slaves/00-INDEX | 4 ++++ Documentation/w1/slaves/w1_therm | 35 +++++++++++++++++++++++++++++++++++ 3 files changed, 41 insertions(+), 0 deletions(-)
diff --git a/Documentation/w1/00-INDEX b/Documentation/w1/00-INDEX index 5270cf4..cb49802 100644 --- a/Documentation/w1/00-INDEX +++ b/Documentation/w1/00-INDEX @@ -1,5 +1,7 @@ 00-INDEX - This file +slaves/ + - Drivers that provide support for specific family codes. masters/ - Individual chips providing 1-wire busses. w1.generic diff --git a/Documentation/w1/slaves/00-INDEX b/Documentation/w1/slaves/00-INDEX new file mode 100644 index 0000000..f8101d6 --- /dev/null +++ b/Documentation/w1/slaves/00-INDEX @@ -0,0 +1,4 @@ +00-INDEX + - This file +w1_therm + - The Maxim/Dallas Semiconductor ds18*20 temperature sensor. diff --git a/Documentation/w1/slaves/w1_therm b/Documentation/w1/slaves/w1_therm new file mode 100644 index 0000000..7b045ae --- /dev/null +++ b/Documentation/w1/slaves/w1_therm @@ -0,0 +1,35 @@ +Kernel driver w1_therm +==================== + +Supported chips: + * Maxim ds18*20 based temperature sensors. + +Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru> + + +Description +----------- + +w1_therm provides basic temperature conversion for ds18*20 devices. +supported family codes: +W1_THERM_DS18S20 0x10 +W1_THERM_DS1822 0x22 +W1_THERM_DS18B20 0x28 +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=. + +w1_therm selects the current slave device for temperature conversion +and provides a strong pullup if the master devices supports one and +delays 750ms for the conversion. + +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). -- 1.4.4.4[unhandled content-type:application/pgp-signature] | |