From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- Documentation/hwmon/ds1621 | 63 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 Documentation/hwmon/ds1621 (limited to 'Documentation/hwmon/ds1621') diff --git a/Documentation/hwmon/ds1621 b/Documentation/hwmon/ds1621 new file mode 100644 index 00000000..5e97f333 --- /dev/null +++ b/Documentation/hwmon/ds1621 @@ -0,0 +1,63 @@ +Kernel driver ds1621 +==================== + +Supported chips: + * Dallas Semiconductor DS1621 + Prefix: 'ds1621' + Addresses scanned: I2C 0x48 - 0x4f + Datasheet: Publicly available at the Dallas Semiconductor website + http://www.dalsemi.com/ + * Dallas Semiconductor DS1625 + Prefix: 'ds1621' + Addresses scanned: I2C 0x48 - 0x4f + Datasheet: Publicly available at the Dallas Semiconductor website + http://www.dalsemi.com/ + +Authors: + Christian W. Zuckschwerdt + valuable contributions by Jan M. Sendler + ported to 2.6 by Aurelien Jarno + with the help of Jean Delvare + +Module Parameters +------------------ + +* polarity int + Output's polarity: 0 = active high, 1 = active low + +Description +----------- + +The DS1621 is a (one instance) digital thermometer and thermostat. It has +both high and low temperature limits which can be user defined (i.e. +programmed into non-volatile on-chip registers). Temperature range is -55 +degree Celsius to +125 in 0.5 increments. You may convert this into a +Fahrenheit range of -67 to +257 degrees with 0.9 steps. If polarity +parameter is not provided, original value is used. + +As for the thermostat, behavior can also be programmed using the polarity +toggle. On the one hand ("heater"), the thermostat output of the chip, +Tout, will trigger when the low limit temperature is met or underrun and +stays high until the high limit is met or exceeded. On the other hand +("cooler"), vice versa. That way "heater" equals "active low", whereas +"conditioner" equals "active high". Please note that the DS1621 data sheet +is somewhat misleading in this point since setting the polarity bit does +not simply invert Tout. + +A second thing is that, during extensive testing, Tout showed a tolerance +of up to +/- 0.5 degrees even when compared against precise temperature +readings. Be sure to have a high vs. low temperature limit gap of al least +1.0 degree Celsius to avoid Tout "bouncing", though! + +The alarm bits are set when the high or low limits are met or exceeded and +are reset by the module as soon as the respective temperature ranges are +left. + +The alarm registers are in no way suitable to find out about the actual +status of Tout. They will only tell you about its history, whether or not +any of the limits have ever been met or exceeded since last power-up or +reset. Be aware: When testing, it showed that the status of Tout can change +with neither of the alarms set. + +Temperature conversion of the DS1621 takes up to 1000ms; internal access to +non-volatile registers may last for 10ms or below. -- cgit v1.2.3