Plant Watering System
By
Ganapathy Nallasivan
Rustem Burkhanov
Saken Istamkulov
Final Report for ECE 445, Senior Design, Spring 2015
TA: Dennis Yuan
6 May 2015
Project No. 51
Abstract
This paper explains the premise and results of our Senior Design project - Plant
Watering System. The plant watering system is an autonomous water administration
system designed for small scale gardens and indoor potted plants. It contains 2 sensor
modules that collect real-time environmental data crucial for plant care and sends it to a
central processing hub that decides and administers the water to the plant system. Our
project was successfully completed during the given time and its usability proven on
potted plants. Here we found the system very efficient for usage for plant growing
beginners. Our results on how reliable the system is on actual plants and possible
improvements we discovered is detailed in this paper.
ii
Contents
1. Introduction .............................................................................................................................................. 1
1.1 Statement of Purpose ......................................................................................................................... 1
1.2 Design Changes ................................................................................................................................... 1
1.3 Block diagram...................................................................................................................................... 2
2 Design......................................................................................................................................................... 3
2.1 Soil Moisture Sensor Unit ................................................................................................................... 3
2.1.1 Soil Moisture Sensor .................................................................................................................... 4
2.1.2 XBee transmitter .......................................................................................................................... 4
2.1.3 Power Supply ............................................................................................................................... 5
2.2 Data Collection and Processing Unit ................................................................................................... 5
2.2.1 Humidity/Temperature Sensor .................................................................................................... 6
2.2.2 Light Intensity Sensor ................................................................................................................... 7
2.2.3 Rain Presence Sensor ................................................................................................................... 7
2.2.4 Receiving XBee ............................................................................................................................. 7
2.2.5 Microcontroller ............................................................................................................................ 7
2.2.6 Bluetooth ..................................................................................................................................... 8
2.2.7 Power Supply ............................................................................................................................... 8
2.3 Phone application ............................................................................................................................... 9
2.3.1 Android Application ..................................................................................................................... 9
3. Design Verification .................................................................................................................................. 11
3.1 Sensor verification ............................................................................................................................ 11
3.1.1 Light Sensor ................................................................................................................................ 11
3.1.2 Rain Sensor................................................................................................................................. 11
3.1.3 Soil Moisture Sensor .................................................................................................................. 12
3.2 Android App , Central Processing Hub Verification .......................................................................... 12
4. Costs ........................................................................................................................................................ 13
4.1 Parts .................................................................................................................................................. 13
4.2 Labor ................................................................................................................................................. 14
4.3 Total Cost .......................................................................................................................................... 14
iii
5. Conclusion ............................................................................................................................................... 14
5.1 Accomplishments .............................................................................................................................. 14
5.2 Uncertainties ..................................................................................................................................... 14
5.3 Ethical considerations ....................................................................................................................... 14
5.4 Future work ....................................................................................................................................... 15
References .................................................................................................................................................. 16
Appendix A
Requirement and Verification Table ................................................................................... 17
iv
1. Introduction
1.1 Statement of Purpose
Home gardens or indoor plants are significant part of any urban dweller’s life in almost
any country. Individuals who try to grow their own small scale gardens or potted plants
often find it cumbersome to consistently and correctly water the plants for optimal
growth. Hence we set out to create the easiest and smartest autonomous gardening
solution. Our purpose was to create a system that can autonomously administer the
right volume of water to up to 2 plant systems simultaneously with preset time intervals.
The system checks environmental conditions using various sensors to obtain real-time
data and as well as weather forecast from the internet if available, to calculate and
release the needed water from the pump at regular time intervals set by the user.
Flexibility of our system provides for a hassle free experience for most new users.
1.2 Design Changes
Initially humidity/temperature and light sensors were planned to be installed at the
separate remote modules, but then it was decided to keep them at the execution module,
because light and air temperature/humidity levels are same across the range our system
provides.
At the beginning it was planned to use the entire Arduino board, however, when the
design was reconsidered, we decided that using the Atmel 328 chip alone is enough for
design purposes. Hence, the efficiency of the system was increased and cost was
decreased as we opted for a PCB.
We also decided to implement a real time warning system that notified the user through
the Android application. We also decided to have the system save all generated warnings
on the Central Processing hub and send it to the Android Application when requested.
1
1.3 Block diagram
The final design consists of 2 separate soil moisture sensor modules that send wireless
signal to the execution module that contains of microcontroller, Bluetooth and remaining
sensors as shown in Figure 1.
Figure 1. Block Diagram
2
2 Design
2.1 Soil Moisture Sensor Unit
We have decided to use two separate autonomous sensor modules that could be
placed up to a radius of 30 meters for indoor applications and up to 90 meters for
outdoor applications from the central hub. Each block consists of a soil moisture sensor,
wireless transmitting unit, dc-dc step-down buck converter and 3 AA battery power
source. The soil moisture sensor is intended to be inserted into the soil surface at a
point next to the plant’s roots. It will measure the moisture level and output an analog
signal. All components except for soil sensor are confined within the plastic box for
protection of electronics and wires. The whole sensor module is immune to any
environmental factors including dirt, rain, wind and sunlight. Our solution for power
source were battery packs. Thus this makes the system completely autonomous and
allows easy transfer of the modules if needed to other plants. Wireless signal transmitter
allows to avoid the excessive usage of wires and transmits accurate signal with
insignificant error. The schematics for soil moisture sensor units 1 and 2 are shown at
Figure 2 and Figure 3.
Figure 2. Soil Moisture Sensor Unit 1 schematic
3
Figure 3. Soil Moisture Sensor Unit 2 schematic
2.1.1 Soil Moisture Sensor
This sensor provides real time soil moisture data to the microcontroller. The sensor is
embedded into the soil at strategic points to ensure soil moisture is at optimum levels at
all required locations. Analog data of soil moisture level from the plant system
environment is delivered from the sensors to the microcontrollers through wireless
transmission. Soil moisture reading is a main component that is used by the
microcontroller to calculate amount of water to be pumped into the plant system. The
sensor provides numerical information on the Soil Moisture Content (%) which is the
unit. 2.1.2 XBee transmitter
2.1.2 XBee transmitter
These transmitters allow for the real time wireless transmission of the analog signals
from the 2 modules to the central hub.
Analog signal of the soil moisture sensor is directly connected to the pin 20 (pin19 for
second identical module) of the XBee transmitter. Pins 1 and 14 are connected to the
output of the buck converter for power supply of 3.3V. Pin 10 connected to ground. The
configuration of the XBee at unit 1 is done with the XCTU software according to Table 1.
Configuration for XBee at unit 2 is given at Table 2.
4
Table 1. XCTU configuration of the transmitting XBee
Parameter
DL
MY
ID
D0
IR
IT
Value
0x13
0x27
0xBADD
2
0x14
5
Table 2. XCTU configuration of the transmitting XBee
Parameter
DL
MY
ID
D1
IR
IT
Value
13
0x26
0xBADD
2
0x14
5
2.1.3 Power Supply
The power source for the soil moisture sensor unit is a set of 3 AA batteries connected
in series that supply voltage in the range of 4.0 to 5.1V. When voltage is below 4V,
batteries need to be replaced. The power supply is directly feeding the soil moisture
sensor. Additionally, power supply output is connected to the step-down dc-dc buck
converter, which outputs voltage 3.3V +/-1% to supply the wireless transmitter.
2.2 Data Collection and Processing Unit
The data collection and processing unit consists of light, rain, air humidity and
temperature sensors, microcontroller, bluetooth transceiver, wireless receiving XBee,
and power supply. We have decided to use these sensors at our main module, because
light, rain, temperature and humidity data is about the same across the garden.
However, for indoor applications one can consider installing separate light sensors at
every plant of interest. The wireless receiver XBee collects soil moisture signals from
remote modules and outputs both signals in analog format directly to the
microcontroller. The microcontroller collects data from all sensors including soil from
XBee receiver and sends it to the phone via serial connection with Bluetooth module.
On the other hand, microcontroller takes sensor data to calculate necessary amount for
watering release to the plant by comparing it to the maximum, which is set by the user
5
from the phone application. The schematic for Data Collection and Processing Unit is
shown in Figure 4.
Figure 4. Data Collection and Processing Unit schematic.
2.2.1 Humidity/Temperature Sensor
This is the sensor that will provide real time relative air humidity level and temperature
data to the microcontroller. Digital data from the plant system environment is delivered
from the sensors directly to the microcontroller. Air humidity and temperature readings
are used by the microcontroller as part of the complex equation that decides the volume
of water to be pumped into the plant system.
6
2.2.2 Light Intensity Sensor
This sensor provides real time sunlight presence and intensity information directly to the
microcontroller as an analog signal. The sensor is placed strategically on different
points to ensure sunlight level is at optimum levels throughout the day. Sunlight level
readings from throughout the day is another component that is used by the
microcontroller to calculate the volume of water to be pumped into the plant system.
2.2.3 Rain Presence Sensor
This is the sensor that will detect the presence of the rain and sends digital signal, high
or low corresponding to no rain/ rain respectively. The sensing plate is recommended to
be mounted with a 45 degree inclination, so water drops are present only during the
rain. The output is directly connected to the microcontroller.
2.2.4 Receiving XBee
Receiving XBee unit receives two wireless signals from two distant soil sensor modules.
They are outputted at pins 6 and 7 as an analog signals identical to the signal sent from
the transmitting XBee. Pins 1 and 14 are connected to 3.3V output of the buck
converter. Pin 10 connected to ground. The configuration of the XBee performed in
XCTU software is illustrated at table 3.
Table 3. XCTU configuration of the receiving XBee.
Parameter
MY
DL
ID
P0
P1
IU
IA
Value
0x13
0x00
0xBADD
2
2
1
0xFFFF
2.2.5 Microcontroller
We decided to use ATmega168P as our microcontroller. It supports both analog and
digital I/O, as well as serial data transfer. Microcontroller takes is directly connected
to Humidity/Temperature, Light and Rain sensors. It is also connected to the Soil
Moisture Sensor Modules via XBEE transceiver, and to the Android application via the
Bluetooth module. At any given time, the microcontroller records sensor readings,
checks if there are any requests from the phone application, processes them if there are
any, and then decides if plants need to be watered.
Communication with the app is done through a request protocol. Whenever a user
needs to send or receive information about the system, the application sends
corresponding request via Bluetooth. Request is a string with a special character at the
beginning defining the type of request. “!” stands for “Create New Profile”, “?” means
7
“Get Sensor Data”, and “*” means “Check for Warnings”. After receiving a request,
microcontroller processes it according to the request type and responds to the app if
needed. “!” request sets the microcontroller parameters, such as Maximum
Temperature, Maximum Soil Moisture, Minimum Relative Humidity, Water Volume and
Watering Time Interval. Only three of the above mentioned parameters, Maximum Soil
Moisture, Water Volume and Watering Time Interval, are used for watering purposes;
other two, Maximum Temperature and Minimum Relative Humidity are used to warn the
user about critical conditions. Upon receiving the “?” request, microcontroller sends all
sensor data to the application as a single string with a “,” character as a delimiter. And
finally, after receiving the “*” request, microcontroller responds information regarding if
there were any warnings during the execution time. That is, if temperature on site
exceeded the user-set Maximum Temperature at some point of time, microcontroller
would respond with the exact time of this occurrence. The same method applies for air
humidity, except that air humidity would need to become lower than Minimum Relative
Humidity for microcontroller to record this warning.
The decision about watering is made based on the following equation:
if ((noRain) AND (Light < MinLight) AND (CurrentSoilMoisture < MaxSoilMoisture))
WaterVolumeDispensed= WaterVolumeSet (MaxSoilMoisture - CurrentSoilMoisture
MaxSoilMoisture - SoilMoistureOffset)
else
WaterVolumeDispensed = 0
where noRain is the output of Rain Sensor representing that there is no rain, Light is the
current light value (%) based on the Light Sensor output, MinLight is the minimum light
value (%) set by a user, CurrentSoilMoisture is the current water content (%) based on
the Soil Moisture Sensor output, MaxSoilMoisture is the maximum water content (%) set
by a user, WaterVolumeDispensed is the amount of water to be dispensed by the
system (cm3), WaterVolumeSet is the amount of water (cm3) that needs to be dispensed
according to the user input, and SoilMoistureOffset is the minimum possible water
content (%) of soil, which varies according to different soil types. The meaning of the If
condition is that the system should not water if it is raining, at night or if the soil is wet
enough (the value of soil moisture exceeds that set by a user).
2.2.6 Bluetooth
This unit allows for the Central Processing Hub to connect over the Bluetooth protocol
to the smartphone and the Android application. The module allows for upto 40 m range
between the smartphone and Central Processing Hub.
2.2.7 Power Supply
The power source for the execution unit is a set of 3 AA batteries connected in series
that supply voltage in the range of 4.0 to 5.1V. When voltage is below 4V, batteries
need to be replaced. The power supply is directly feeding the sensors, microcontroller
and Bluetooth. Additionally, power supply output is connected to the step-down dc-dc
buck converter, which outputs voltage 3.3V +/-1% to supply the wireless receiver.
8
2.3 Phone application
2.3.1 Android Application
The smartphone application is written for Android-based phones. Communication with
the rest of the plant watering system is done through a request protocol. Whenever a
user needs to send or receive information about the system, the application sends
corresponding request via Bluetooth. Request is a string with a special character at the
beginning defining the type of request. “!” stands for “Create New Profile”, “?” means
“Get Sensor Data”, and “*” means “Check for Warnings”.
Android application will be used by the user to create “profiles” for different plants up to
8 different profiles. The profiles are stored permanently on the phone using a module
called Tiny Database. The application can also be used to view the data collected by
the microcontroller in real time. Also whenever the user sends a request for warnings to
the microcontroller in the central processing hub it receives back the accumulated
warnings that were stored in the microcontroller. The user can enter the needed settings
for each profile which will be used by the microcontroller as reference to process the
sensor data. All the settings data is sent as one concatenated string for better
assurance of data being transferred successfully. The application also has internet
capabilities. If an internet connection is available then it can successfully pull weather
data based on the location it has detected. The application also has preset settings for
some commonly grown plants such as Viola,Rose and a few more. Since the
application works with the Central Processing Hub as a pair the works of this part of the
system could be better understand from a visual flowchart. Figure 5 shows this.
9
Figure 5. Android Application and Remaining system Flow Chart
10
3. Design Verification
3.1 Sensor verification
For testing sensors separately from the system, 5V and GND outlets from the lab kit box
were used, whose voltage supply was equal to 5.15V, measured with the voltmeter. All
measurements of analog signals were made with the multimeter provided in the lab kit.
For all sensors Vcc = 5.15V
3.1.1 Light Sensor
Light sensor is a photoresistor board with Vcc, GND and Vout analog output. After
connecting it to the Vcc and GND the light was altered from full light (using the
flashlight) to complete darkness. Testing data is illustrated in the Table 4.
Table 4. Light Intensity Sensor testing results.
Light Intensity (%)
0
25
50
75
100
Sensor Output (V)
5.15
3.94
2.67
1.37
0.13
As can be observed from testing results, light sensor output shows linear dependence
from the light intensity, which makes usage of this sensor easy for equation calculation.
Thus, the verification of light sensor is in accordance with our requirements.
3.1.2 Rain Sensor
Rain sensor has 4 pins: Vcc, GDN, Vao – analog output, Vdo – digital output. Sensor
consists of the rain detection pad – where stripes of conductor could be shorted with
water drops, which would change its resistance, and A/D converter circuit board. Water
drops were added and output data measured from completely dry to completely wet
conditions. The digital output of the sensor was showing high value for “no rain”
condition and low for “rain” condition as illustrated in Table 5.
Table 5. Rain Presence Sensor testing results
Rain Intensity (%)
0
30
70
100
Digital Output of Rain Sensor (V)
5.14
0.74
0.43
0.13
As can be concluded from the table, the sensor output indicates “no rain” condition as
high signal and “rain” condition as low signal.
11
3.1.3 Soil Moisture Sensor
Soil moisture Sensor has Vcc, GND, Vdo and Vao pins. Different levels of moisture
were applied on the sensor starting from completely dry to completely wet (all in water)
conditions. The testing results are shown in Table 6.
Table 6. Soil Moisture Sensor testing results
Soil Moisture Level (%)
0
25
50
75
100
Sensor Output (V)
5.14
4.5
3.7
3.3
2.6
From Table 6 we can observe that output varies from 5.14V to 2.6V, which satisfies our
requirements, because this output range can be used to adjust the watering equation in
the microcontroller code.
3.2 Android App and Central Processing Hub Verification
Here we have the actual number values from testing the plant watering system. This
was the best way to verify Android App and the Central Processing Hub. Table 7 shows
us the changes in watering volumes when the Soil moisture values are varied. The
equation mentioned earlier in the Microcontroller section is used to calculate the new
watering volumes. Table 8 on the next page shows the changes in watering volumes
when light intensity and rain presence is varied. We can observe from this table that in
darkness (light sensor reading reflect that) and rain presence both prevent any watering
from happening.
Table 7. Watering results when Soil Moisture levels varied
12
Table 8. Watering results when light presence and rain presence varied
4. Costs
4.1 Parts
Table 9. Parts Cost
Part
Buck Converter
JY-MCU Bluetooth
Module
Air
Humidity/Temperature
Sensor
Soil Moisture Sensor
Rain Sensor
Light Sensor
Male-to-female cable
Box
Battery holder
XBee explorer board
Arduino testing Kit
Xbee
Small testing
breadboards
AA battery
Machine Shop Hours
Electronic Service Shop
Hours
Total
Manufacturer
Traco Power
N/A
Quantity
Retail Cost ($)
3
15.00
1
11.00
Actual Cost ($)
45.00
11.00
Shanghai
4
2
7.99
N/A
N/A
N/A
N/A
ECE store supply
ECE store supply
Sparkfun
Arduino
Digi
ECE store supply
2
1
1
20
3
6
1
1
3
2
5
7.85
6.99
0.25
12.09
1.03
30.00
20.00
30.00
7.00
10.00
7.85
6.99
5.00
36.27
6.23
30.00
20.00
90.00
14.00
15
2 hours
4 hours
0.53
22.00
35.00
8.00
44.00
140.00
RadioShack
ECE
ECE
482.33
13
4.2 Labor
Table 10. Labor Cost
Name
Hourly Rate ($)
Total hours invested
Saken
Ganapathy
Rustem
Total
30
30
30
200
200
200
Total = Rate x Hours x
2.5 ($)
15000
15000
15000
45000
4.3 Total Cost
Total cost of the project is estimated to be $45482.33
5. Conclusion
5.1 Accomplishments
We were able to successfully complete every aspect of our project we had initially set
out to do. Our results backed our statement of purpose and we were able to
successfully utilize the system on 2 Viola potted plants for autonomous watering. Most
importantly the Android Application turned out to be very user - friendly and when we
tested on new users they were intuitively use it without any explicit instructions. As our
end user doesn’t necessarily have to have many technically skills this was an important
accomplishment.
5.2 Uncertainties
Due to time constraints we were unable to test the longevity of our system. We tested
for a duration of a week so we are uncertain for how long the sensor modules and
Central Processing Hub would weather outdoor conditions before requiring any form of
human intervention. Even though in theory our components are sealed and prevent any
outdoor elements from damaging the electronics inside this hasn’t been tested for long
periods such as 6 months. Another uncertainty is again the improved plant growth that
this system would provide over normal human watering when tested over durations of
longer than 6 months.
5.3 Ethical considerations
All elements of our watering system are concealed within the plastic insulating box, so
all parts are stored inside except for sensing units. This design prevents user from
damaging small electronic part and avoids possible electrical shock. [6]
14
5.4 Future work
We believe our system can be successfully implemented in small scale gardens and
urban indoor plants in the future. Inexperienced but enthusiastic plant growers could
use our system as a great introduction into plant growing for a hassle free start.
Moving forward we can add the following improvements.
Perhaps given more time we could perform greater research to optimize our Central
Processing Hub equations to achieve better accuracy and improved water savings.
We could also look into scaling this system to include more sensors modules and
increased range. The bottleneck in our current project was processing power. The
Atmel 328 microprocessor currently used has nearly maxed its capacity so we would
have to look at alternative ways of distributing the processing load.
We could also introduce an artificial lighting source that would help provide the plant
with consistent light intensity levels even when natural lighting sources are not up to
what the user prefers. This would be including some sort of UV light source that could
be complemented with our existing light sensors.
15
References
[1] D-ROBOTICS. DHT11 Humidity & Temperature Sensor. [Online]. Available:
http://www.micropik.com/PDF/dht11.pdf
[2] Dodabalapur A. (1995). Organic Heterostructure Field-Effect Transistors. Science
[Online]. 269.5230: 1560-562. Available:
http://www.ti.com/lit/ds/symlink/lm393-n.pdf
[3] Digi Corp. XBee ® /XBee-PRO ® RF Modules. [Online]. Available:
https://www.sparkfun.com/datasheets/Wireless/Zigbee/XBee-Datasheet.pdf
[4] ATMEL Corp. Atmel 8-Bit Microcontroller with 4/8/16/32KBytes In-system
Programmagle Flash Datasheet. [Online]. Available:
http://www.atmel.com/images/Atmel-8271-8-bit-AVR-Microcontroller-ATmega48A48PA-88A-88PA-168A-168PA-328-328P_datasheet_Complete.pdf
[5] Linear Technology Corp. LTC1514-3.3/LTC1514-5 - Step-Up/Step-Down Switched
Capacitor DC/DC Converters with Low-Battery Comparator. [Online]. Available:
http://cds.linear.com/docs/en/datasheet/151435f.pdf
[6] Institute of Electrical and Electronics Engineers, Inc. (2006). IEEE Code of Ethics.
[online]. Available:
http://www.ieee.org/about/corporate/governance/p7-8.html
16
Appendix A
Requirement and Verification Table
Requirements
Verification
1) DHT 11 - Temperature and Air
Ensure the following criteria:
Humidity sensor [1]
 when power is supplied to sensor,
This dual sensor needs to output a UART
don't send any instruction to the
digital signal to output real-time
sensor within one second to pass
temperature and humidity data to
unstable status
microcontroller.
 connected to Vdd and GND;
Need:
humidity accuracy +/-2%RH (Relative
Humidity)
temperature accuracy +/-0.2% C
power supply in the range of 3.3-6V
The Complete range detection 0 - 100 %
of Relative Humidity
Checking procedure:
 connect oscilloscope probe to
output signal of the sensor
 check the signal pattern - digital
characteristic signal should be
displayed on the screen
 alternatively, connect sensor output
to Arduino digital inout and write
code to display signal data on the
computer
 check outside temperature and
humidity with the thermometer and
check if error is within required
margins
17
2) Soil Moisture Sensor [2]
This sensor needs to output an analog
signal to output real-time soil moisture
(unit:Water Content) data to
microcontroller.
Need:
Error +/-2.5% wfv (water fraction by
volume)
Power supply is set in the range of 3.35V
Ensure the following criteria:
 power indicator LED is on (red)
 output is low when humidity
exceeds set threshold value
Checking procedure:
 connect oscilloscope probe to
output signal of the sensor
 check the signal pattern - analog
characteristic signal should be
displayed on screen
 alternatively, connect voltmeter at
the output, check how voltage
changes with sensor under
different moisture conditions
 measure soil moisture with the
digital detector, check if error is
within required range
3) Light sensor
This sensor needs to detect
luminescence and sends analog signal to
output real-time light data to
microcontroller.
Need:
AD converter with the error of +/-2%.
Power supply is set to 5V +/-0.5V
Checking procedure:
 connect oscilloscope probe to
output signal of the sensor
 check the signal pattern - analog
characteristic signal should be
displayed on the screen
 alternatively, connect voltmeter at
the output, check how voltage
changes with sensor under
different moisture conditions
 measure insolation and check if the
error is within required range
4) Rain sensor [2]
Ensure the following criteria:
 power indicator LED is on
This sensor needs to detect the presence
of rain and sends analog signal to output
Checking procedure:
real-time data to microcontroller.
 connect oscilloscope probe to
analog output of the sensor
Need:
18

Rain presence accuracy 90%
Power supply is in the range 3.3-5V
Analog output provides intensity of the
rain


5) Analog signal transmitter [3]
Need:
Outdoor range ~90m
Indoor range ~30m
Power supply in the range 2.8-3.4V
Outputs unicast digital waveform
check the signal pattern - analog
characteristic signal should be
displayed on the screen for probe
alternatively, connect voltmeter at
the output, check how voltage
changes with sensor under
different moisture conditions
check presence of the rain by
observation, then check if the
sensor detects it in 9 cases out of
10.
Ensure the following criteria:
 transmitter power 1mW
 peak current 45mA
 no-power current <10uA
 power supply in the range 2.8-3.4V
Checking procedure:
 connect oscilloscope probe to
analog input signal of the sensor
 remove the transmitter to 30m
indoors and 90m outdoors from the
receiver, check if receiver gets
accurate signal from transmitter
6) Analog signal receiver [3]
Need:
Outdoor range ~90m
Indoor range ~30m
Receives unicast digital waveform
Power supply in the range 2.8-3.4V
7) Microcontroller [4]
Needs:
Temperature Range(C): - 40 to 125
flexible for outdoor conditions
Checking procedure:
 connect oscilloscope probe to
analog output signal of the sensor
 same analog pattern as in signal
input of the transmitter should be
displayed on screen
 remove the receiver to 30m indoors
and 90m outdoors from the
transmitter, check if receiver gets
accurate signal from transmitter
Checking procedure:
 connect oscilloscope probe to
analog output signal of the sensor
19
Operating Voltage Range(V): 2 to 5.5

Program Memory Type: Flash
Timers
2 x 8-bit, 1 x 16-bit

same analog pattern as in signal
input of the transmitter should be
displayed on screen
is able to connect with Android
phone using Bluetooth
Comparators: 2
8) Android Phone
Needs:
 Ability to run companion app.
 Easy to navigate and simplified UI
to allow ease of accessibility
 Connects to microcontroller using
Bluetooth
Checking procedure:
 visual observation
 test if our companion app works
effortlessly without any glitches
 is able to connect with
microcontroller using Bluetooth
9) Power Supply [5]
Checking procedure:
 measure voltage values with the
multimeter
 check if supplied voltage is within
the required tolerance
power supplies required 5V+/-1V and
3.3V+/-0.3V



Battery supply for sensor units.
Battery supply for Microcontroller.
Supply enough voltage to power
on the microcontroller
All the individual components
(including sensors) power on and
work consistently
20