LMTEMP(4) | Device Drivers Manual | LMTEMP(4)

# NAME

lmtemp — National Semiconductor LM75, LM77 and compatible hardware monitors

# SYNOPSIS

lmtemp0 at iic? addr 0x48 flags 0x0000

# DESCRIPTION

The lmtemp driver provides support for the National Semiconductor LM on iicbus series temperature sensors and register compatible chips.
Each device is specified by the value of the address and flags.

Device | addr | flags
`LM75` | 0x48 - 0x4f | 0x0000
`LM75A` | 0x48 - 0x4f | 0x0000
`DS75` | 0x48 - 0x4f | 0x0001
`LM77` | 0x48 - 0x4b | 0x0002

# HARDWARE

Chips supported by the lmtemp driver include:

Device | Range | Resolution
`National Semiconductor LM75` | -55 – +125 | 0.5 degC
`Texas Instruments LM75A` | -55 – +125 | 0.5 degC
`Dallas Semiconductor DS75` | -55 – +125 | 0.0625 degC
`National Semiconductor LM77` | -55 – +130 | 0.5 degC

The LM75, LM75A, and DS75 have a programmable high temperature limit. When this is exceeded, the device asserts an over-temperature output.
The LM77 has programmable low and high temperature limits. Exceeding either of these causes the device to assert an interrupt output. It also has a programmable critical high temperature limit, and exceeding this causes the device to assert a separate critical alarm output.
The sensor and limit values are made available through the envstat(8) interface.

# SEE ALSO

envsys(4), envstat(8)

# HISTORY

The lmtemp device appeared in NetBSD 4.0.

# BUGS

Interrupt support is unimplemented.

January 1, 2016 | NetBSD 8.0