AM2315TEMP(4)

AM2315TEMP(4) | Device Drivers 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 <brad@anduin.eldar.org>.

# 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.

December 28, 2017 | NetBSD 9.5