NAME
lm75 — lm75 i2c digital temperature sensor driverSYNOPSIS
device iicdevice iicbus
device lm75
DESCRIPTION
The lm75 driver provides access to sensor data and configuration over the iicbus(4). It provides an easy and simple way to check the functionality of an i2c bus as it provides read and write access to the lm75 configuration register. The access to lm75 data is made via the sysctl(8) interface:dev.lm75.0.%desc: LM75 temperature sensor dev.lm75.0.%driver: lm75 dev.lm75.0.%location: addr=0x49 dev.lm75.0.%pnpinfo: name=lm750 compat=national,lm75 dev.lm75.0.%parent: iicbus3 dev.lm75.0.temperature: 27.1C dev.lm75.0.thyst: 75.0C dev.lm75.0.tos: 80.0C dev.lm75.0.faults: 1 dev.lm75.0.mode: comparator dev.lm75.0.polarity: active-low dev.lm75.0.shutdown: 0
- dev.lm75.%d.temperature
- Is the read-only value of the current temperature read by the sensor.
- dev.lm75.%d.thyst
- Sets the hysteresis temperature. Once the temperature gets over the overtemperature shutdown value (tos) it needs to drop below the hysteresis temperature to disable the output (interrupt) pin again.
- dev.lm75.%d.tos
- Sets the overtemperature shutdown value. Once the temperature gets over this value the output pin will be enabled. The way the output (interrupt) pin works, depends on the mode configuration.
- dev.lm75.%d.faults
- Is the number of faults that must occur consecutively to activate the interrupt (output) pin. It can be set to 1, 2, 4, and 6.
- dev.lm75.%d.mode
- Sets the operation mode for the sensor interrupt pin. It can be set to 'comparator' (default) or 'interrupt'.
- dev.lm75.%d.polarity
- Sets the polarity of the sensor interrupt pin. It can be set to 'active-low' (default) or 'active-high'. Please note that the output pin is an open-drain output and it needs a proper pull-up resistor to work.
- dev.lm75.%d.shutdown
- When set to '1' it shuts down the sensor. The temperature conversion stops but the sensor remains with its i2c bus active, i.e., it can be woken up by setting this option to '0' again.
MIPS, these values are configurable for
lm75:
- hint.lm75.%d.at
- Is the iicbus(4) you are attaching to.
- hint.lm75.%d.addr
- Is the lm75 i2c address on the iicbus(4).
ARM, the DTS part for a
lm75 device usually looks like:
i2c {
/* Properties describing the controller appear here. */
...
lm750@49 {
compatible = "national,lm75";
reg = <0x49>;
};
};
- compatible
- Should always be set to "national,lm75".
- reg
- Indicates which 7-bit i2c address the lm75 is wired at. lm75 temperature sensors can be wired to 8 different addresses, allowing up to 8 sensors on the same iicbus(4).
SEE ALSO
snmp_lm75(3), fdt(4), iic(4), iicbus(4), sysctl(8)HISTORY
The lm75 driver first appeared in FreeBSD 11.0.AUTHORS
The lm75 driver and this manual page were written by Luiz Otavio O Souza <[email protected]>.| December 26, 2017 | Debian |