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 9.4