Category Archives: Electronics Projects

Beehive Instrumentation Project-5: Case Installation and Temperature-Humidity Measurement Test in Hive

In this installment, I show the installation of the Raspberry Pi 2B into an obsolete NiMH charger case, along with the switching regulator to convert 18V to 5V.

Charger case RPi test fit

Test fit of the RPi 2B into old Ryobi charger case.

For the first test in one of our bee hives, I connected the Adafruit’s HTU21D-F breakout to the Pi’s GPIO header with a solderless prototyping board and proto jumper wires.

RPi Li-ion case install and Hive Test

Prototype board connection of T-H sensor to RPi.

I have mounted the sensor in a cut down plastic potting box, with 1/8″ holes for airflow.  Hopefully the holes will exclude bees, but not make it easy to plug with propilis.

T-H sensor case

Case for HTU21D-F breakout. (Potting box from DigiKey.)

For an initial test, I set the battery-computer assembly on the inner cover in the hive, and draped the T-H sensor through the access hole in the cover, on top of the frames.  (As is typical of Alaska beekeeping, we are still sustaining the bees with sugar syrup. Should have nectar in a week or so.)

I was skeptical about the long-range WiFi through the aluminum-clad top cover out in the yard, but the longer range WiFi USB dongle (Adafruit) is providing a very strong signal.

RPi inner cover test 6-10-15

Still using the Python code posted by Davespice to configure and read the sensor (see installment 3):

I’m operating the RPi through Putty SSH, as before.

Temperatue Humidity 6-10-15-1

The results show temperatures around 23 deg C (73 deg F) and relative humidity at first of about 47% (the RH fluctuated down to ~41 % after about 20 minutes, then rose again–not sure why).  The home weather station shows about 62 deg F and 52% RH.  The difference in humidity is probably due to the temperature difference, but I sort of expected it to be more humid in the hive, with all the sugar syrup curing in there (lots of pollen, but still waiting for the major nectar flow to start).
I was planning to build a small enclosure to hold the computer and battery at the back of the hive box. If the system works okay inside a spacer box on top of the inner cover, though, I might just stay with that.

Further intended developments include:

  • IR camera and illuminator (Pi NOIR camera)
  • A multiplexer for T-H sensors in additional hives.  This should allow a row of hives to share one RPi and battery for economy.
  • Battery monitoring.  Also have a few parts lying around for a solar charger with 4xAA batteries.
  • Hive weight measurement, taring, calibration, and logging.

Beehive Instrumentation Project-4: Adafruit HTU21D-F Temperature-Humidity Sensor Breakout Test

Among the most important things we want to monitor from beehives are temperature and humidity in the hives.  For convenience, I chose Adafruit’s breakout board for the HTU21D-F chip.


To test the sensor, I used code posted by Davespice:

Here is a sample of the output over SSH:

Rpi HTU21D-F ouput 2

Looks like the corner of to upstairs room is a bit warm.  Relative humidity started about 33%, and rose to 41% when I exhaled onto the sensor.

Beehive Instrumentation Project-3: Apache Server, Python in PHP

While running the Raspberry Pi 2-B off the drill battery, I installed the Apache-2 server and MySQL.

See for details.

I want to run the temperature and humidity logging, IR and USB cameras, and other possible instruments like weight measurement from a local web server on the remote RPi.  The first step is to run a PHP script on the server, which in turn selects the “driver” code for the attached devices.  The learning PHP script runs a simple Python script.

See for the basic ideas.

I wrote the PHP script “index.php”, which is placed in the RPi directory /var/www, where the Apache server runs it as the default start up code instead of index.html.

echo “hello world.”;
echo “<br>”;
$command = escapeshellcmd(‘python’);
$output = shell_exec($command);
echo $output;
echo “<br> I’m here in php”;

The Python script “”:

#!/usr/bin/env python
print “I’m here in Python”

When the IP address of the RPi is entered into the Firefox browser, this is the result:

RPi2B server Firefox browser image

RPi2B server Firefox browser image

Beehive Instrumentation Project-2: Raspberry Pi 2 on 18V Drill battery power

RPi 2 with 18V drill battery power.

RPi 2 with 18V drill battery power.

Last post, I checked out the UBEC as a DC-DC converter to power the Raspberry Pi 2-B from a Ryobi 18 V tool battery.  This time, I actually plugged the RPi into the battery power.  I attached the 5V output leads to a USB socket so the RPi could be powered through the micro USB connector for additional protection.

So far, I have operated the RPi2 from the battery for over 8 hours, including working on the Apache server (see later) over SSH, and an HDMI connection to a TV part of the time.  Battery open-circuit voltage dropped from ~22V to 17.35V.  Looks promising so far.  I’m planning a battery monitor using one of the channels of the MCP3008 analog-digital converter for a more accurate measurement of power status.

Beehive Instrumentation Project-1: 18V Drill battery power for Raspberry Pi 2

Test of UBEC (Adafruit#1385) connected to 18V Li. Using obsolete NiMh charger case for battery connector- there’s room for RPi2 in there.

Will need to source parts, rather than using salvage.  Checkout with the Raspberry Pi 2 next.

Testing Adafruit UBEC with 18V Li drill battery.

Testing Adafruit UBEC with 18V Li drill battery.