AM2315TEMP(4) FreeBSD Kernel Interfaces Manual AM2315TEMP(4)
NAME
am2315temp - Driver for Aosong AM2315 sensor chip via I2C bus
SYNOPSIS
am2315temp* at iic? addr 0x5c
DESCRIPTION
The am2315temp driver provides measurements from the AM2315
humidity/temperature sensors via the envsys(4) framework. The am2315temp
addr argument selects the address at the iic(4) bus. The AM2315 has
limits on how often the measurements can be read. Adjustments to the
number of times to take reading before considering it valid, and the
number of ticks to wait between readings can be changed through sysctl(8)
nodes.
There are other oddities about the AM2315 that should be mentioned. The
datasheet says that the device should read no more often then every 2
seconds, further, it also implies that a measurement is not performed
until the device is 1) awake 2) has been asked for a measurement. From
observation, it has been noted that it is possible to ask for
measurements more often than every 2 seconds, and actually get something
that looks to be valid. It may, in fact, be valid, but it has also been
noted that the measurements do not appear to change. This implies that a
measurement was done, and then returned time and time again. It has also
been noticed that if measurements are taken very close to every 2
seconds, that sometimes the device will return a I2C error on a read. If
this happens a lot, increase hw.am2315temp0.readticks a bit.
SYSCTL VARIABLES
The following sysctl(3) variables are provided:
hw.am2315temp0.readcount
The number of times to take a reading before considering it
valid. This defaults to 2.
hw.am2315temp0.readticks
The number of ticks to wait in between readings. The default is
100.
hw.am2315temp0.debug
If the driver is compiled with AM2315_DEBUG, this node will
appear and can be used to set the debugging level.
SEE ALSO
envsys(4), iic(4), envstat(8), sysctl(8)
HISTORY
The am2315temp driver first appeared in NetBSD 8.0.
AUTHORS
The am2315temp driver was written by Brad Spencer
<
[email protected]>.
BUGS
The device does not appear to work with the gpioiic(4) bitbang
controller. When tried, reads would not error, but no data was returned.
FreeBSD 14.1-RELEASE-p8 December 28, 2017 FreeBSD 14.1-RELEASE-p8