The ordered weather sensors arrived so I ... / 2011-04-30

The ordered weather sensors arrived so I want to test them using w1retap. Time for rounds of configure / fix missing stuff. The resulting logging will be to postgres / rrdtool but I want to test with filebased logging first just to make sure the sensors work.

The configure script of w1retap insists on libxml2-dev and I don't see an easy way to disable this test. On the planned low-power, running from ramdisk weather station computer I won't allow for unused libraries, but for now the easy solution is just installing that library. Even ./configure --without-applet --disable-xml or ./configure --without-applet --disable-xml2 or other variants show:

checking for xml2-config... no
configure: error: missing program 'xml2-config'; is 'libxml2' or
'libxml2-devel' installed?

Fixed by installing libxml2-dev. The next thing it insists on is pkg-config and gmodule-2.0. The gmodule library is needed for dynamic loading of modules. This comes from ubuntu package libglib2.0-dev. The last bit is libusb-dev. Now I can build the package. First everything needs to run as root, but I fixed that later with

# chmod 666 /dev/bus/usb/001/002

Later improvement will be to find an udev rule which does this automatically for device:

Bus 001 Device 002: ID 04fa:2490 Dallas Semiconductor DS1490F 2-in-1 Fob, 1-Wire adapter

With the humidity, temperature, solar sensor and the barometer I see:

# w1find DS2490-1
(1) 108FB1130208003E    18S20:high precision digital thermometer
(2) 26C1E0F1000000ED    2438:smart battery monitor
(3) 26BD60B50000002D    2438:smart battery monitor
(4) 81AF632F00000067    :Serial ID Button

With just the barometer:

# w1find DS2490-1
(1) 26BD60B50000002D    2438:smart battery monitor
(2) 81AF632F00000067    :Serial ID Button

The general config is by default in ~/.config/w1retap/rc, where I have:

init = w1file
log = w1file=/tmp/w1log
altitude = 2
device = DS2490-1

It took a bit of browsing in the documentation, but the first three sensors were easy to set up in ~/.config/w1retap/sensors:

# w1retap sensors
26BD60B50000002D:HB-BARO:Pressure:PRES:hPa::
108FB1130208003E:DS1820:Temperature:TEMP0:⁰C::
26C1E0F1000000ED:MS-TH:Humidity:HUMI:%::

And the results:

Pressure=986.59 hPa
Temperature=32.25 ⁰C
Humidity=29.06 %
udate=1304169061
date=2011-04-30T15:11:01+0200

It took a bit more to get the Solar sensor working. The DS2438 is used for both the humidity and the solar sensor according to the hobby-boards documentation for the Humidity / Temperature / Solar sensor. Browsing the samples suggests I should configure it as a DS2438 sensor with dual measurements, like

26C1E0F1000000ED:DS2438:Solar:Solar (Vsens):mV:VTMP:Temperature GHT2:⁰C::

And indeed I get a reading:

Solar=0.49 mV
VTMP=33.34 ⁰C

Switching the light in the shed back off makes the readout drop to 0, so I believe I am looking at the right value.

And now the logging works too, after waiting a bit:

2011-04-30T15:42:00+0200 Pressure 986.591492 hPa
2011-04-30T15:42:00+0200 Temperature 31.312500 ⁰C
2011-04-30T15:42:00+0200 Humidity 29.057188 %
2011-04-30T15:42:00+0200 Solar 0.000000 mV
2011-04-30T15:42:00+0200 VTMP 32.531250 ⁰C
2011-04-30T15:44:00+0200 Pressure 986.369263 hPa
2011-04-30T15:44:00+0200 Temperature 31.312500 ⁰C
2011-04-30T15:44:00+0200 Humidity 29.373028 %
2011-04-30T15:44:00+0200 Solar 0.000000 mV
2011-04-30T15:44:00+0200 VTMP 32.531250 ⁰C

Update 2011-05-01: Found the udev rule in the w1retap documentation:

root@metcalfe:/etc/udev/rules.d# cat 45-local-usb-special.rules 
#
SUBSYSTEMS=="usb", GOTO="usb_w1_start"
GOTO="usb_w1_end"
LABEL="usb_w1_start"
ATTRS{idVendor}=="04fa", ATTRS{idProduct}=="2490", GROUP="w1retap",
MODE="0666"
LABEL="usb_w1_end"