MONK MAKES 00096 BBC MICRO:BIT Plant Monitor Instructions
- June 4, 2024
- MONK MAKES
Table of Contents
00096 BBC MICRO: BIT Plant Monitor
Instructions
WARNING
Only the prong of the Plant Monitor below the white line should be allowed to get wet. If the top of the board gets wet, disconnect it from everything, dry it using a paper towel and then leave it the throughly dry out before trying to use it again.
INTRODUCTION
The MonkMakes Plant Monitor measures soil moisture, temperature, and relative humidity. This board is compatible with the BBC micro: bit, Raspberry Pi, and most microcontroller boards.
- Superior capacitative sensor (no electrical contact with soil)
- Alligator/crocodile clip rings (for use with BBC micro: bit and Adafruit Clue etc.
- Ready soldered header pins for Arduino and other microcontroller boards.
- Easy to use UART serial interface
- Additional analog output for moisture only
- Built-in RGB LED (switchable)
USING THE PLANT MONITOR
The plant monitor should be placed as shown below.
The front side of the prong should be as close
to the edge of the pot as possible.
The sensing all takes place from the far side of the prong.
The electronics should be facing out of the pot and the prong of the Plant
Monitor pushed into the dirt as far as the white line (but no deeper).
It’s a good idea to attach the alligator clip leads to connect to the Plant
Monitor before positioning it in the plant pot.
Once powered up, the plant monitor will immediately start displaying the level
of wetness using the built-in LED. Red means dry, and green means wet. Before
you put the Plant Monitor in the pot, try gripping the prong in your hand and
the moisture of your body should be enough to alter the LED’s color.
MICRO:BIT
To make full use of wetness, temperature, and humidity readings from the Plant
Monitor, connect it up as shown below.
The red and black leads provide power from the
micro: bit to the Plant Monitor and the yellow and green leads send serial
data to and from the Plant Monitor.
There is a Make code extension for the Plant Monitor that makes it easy to
write code and the best way to get started is to load the example project from
here:
https://makecode.microbit.org/_XK0cdj3u49Yg
When you download this project onto your micro: bit it will show the wetness
using the bar graph block. Pressing button A will show the temperature in
degrees C and pressing button B, the relative humidity as a percentage.
Here’s the code:
The on-start block must contain the block
Start Plant Monitor , which initiates communication between the micro: bit
and the Plant Monitor. The variable show_wetness is used to switch the
displaying of the bar graph on and off, otherwise, it will try and draw the
bar graph over the top of the temperature and humidity readings.
The forever block uses the block Plant Wetness and displays it as a bar graph
as long as show_wetness is true.
When button A is pressed, the screen is cleared and show_wetness set to false,
and then the temperature is displayed. After a pause for you to read the
temperature, show_wetness is set to true again so that the bar graph continues
refreshing.
The button B code is much the same, except that the relative humidity is
displayed rather than the temperature.
You can see the Plant Monitor extension in the Palette – it has an icon of a
tree.
As well as the Start Plant Monitor, Plant
Humidity, and Plant Temperature blocks, there are also blocks that turn the
LED on and off.
The Plant Wetness Analog block allows you to measure the wetness using the
Plant Monitor’s analog output pin. This is useful if you want to use the Make
code plotting facility, as this is not possible using the serial interface.
To use the analog interface, connect your micro: a bit like this:
As before, power is supplied by the micro: bit,
but this time, micro: Bit pin 0 is used to connect to the analog output of the
Plant Monitor.
Connecting the Plant Monitor in this way only measures wetness, but it does
mean that because the serial interface of the micro: bit is not used, it can
be used to send serial data back to Makecode’s plotting feature. Try out the
project here:
https://makecode.microbit.org/_YEL61KA0cKDd
The code for this is really quite minimal.
If you have your micro: bit paired to the Make
code editor in your browser, then as soon as the program has uploaded, you
should see an option Show Console Device appear. Clicking on this will show a
real-time plot of the wetness reading.
TROUBLESHOOTING
Problem: When I first connect power to the PlantMonitor, the LED cycles
through colors. Is this normal?
Solution: Yes, this is the Plant Monitor doing a self-test as it starts
up.
Problem: The LED on the Plant Monitor does not light at all.
Solution: Check the power connections to the Plant Monitor. Alligator
leads can become faulty. Try changing the leads.
SUPPORT
You can find the Product’s information page here: https://monkmakes.com/pmon
including a datasheet for the product.
If you need further support, please email
support@monkmakes.com.
MONK MAKES
As well to this kit, MonkMakes makes all sorts of kits and gadgets to help
with your electronics projects. Find out more, as well as where to buy here:
https://monkmakes.com you can also follow MonkMakes on Twitter @monkmakes.
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