This article focuses on the use of super inexpensive wireless modules that can provide one-way communications capabilities over a reasonable distance.
These modules are also very tiny, allowing you to incorporate a wireless interface into virtually any project.
These modules make use of ASK modulation.
Step 2: Theory – ASK (Amplitude Shift Keying)
In Amplitude Shift Modulation the amplitude (i.e. the level) of the carrier wave is changed in response to the incoming data signal. This is sometimes called Binary Amplitude Shift Modulation as there really are only two levels to be concerned with:
Digital 1 – This drives the carrier at full strength
Digital 0 – This cuts the carrier off completely
Step 3: Antenna Design
One wavelength at 433MHz is 69.24 cm. As this is a pretty long antenna it is more practical to use a half or quarter wave antenna.
Most experimenters use a quarter wave antenna which works out to about 17.3 cm .
It is common to coil the wire on one or both antennas to reduce the size. We can experiment with antenna coils by wrapping the wire around a pencil or pen.
Step 4: Application – Bike Direction Indicator
The application is a use case of the 433 Mhz modules.
Requirements:
A joystick is used to indicate direction, right, left, stop, and emergency indications
The directions data are transmitted asynchronously when events occur
The receiver wakes up on Joystick events and make actions by Lighting up the wanted LEDs array
The receiver includes an OLED display
An MPU6050 a 3-axis Gyroscope with Micro Electro Mechanical System(MEMS) technology may replace the Joystick
The gadget is to be installed firmly on a bike
Three boards are designed for this application
433 MHZ tx board
433 MHZ rx board
2 LEDs arrays
Step 5: 433 MHZ TX Board
The 433 MHZ TX module is simple to interface to our ATTINY85 µController.
Step 6: 433 MHZ RX Board
The 433 MHZ RX module is simple to interface to our ATTINY85 µController.
This article is a demonstration of the use of the Ultrasonic Distance Sensor HC-SR04.
The sensor will be be used as a measurement device to build the “1 Meter Keep Away Alarm Gadget“ for distanciation purposes.
The brain of this gadget is the wonderful ATTINY85 µController powered by a 3.7V Lipo battery.
The gadget integrates the TP4056 charger.
A GREEN LED lights if the measured distance from any object is greater than 120 cm.
A RED LED blinks if the measured distance from any object is lower than 100 cm with a lovely (noisy) beep.
A YELLOW LED blinks if the measured distance from any object is between [100,120 ] cm with a less noisy beep.
Supplies:
Many articles explain in details how the HC-SR04 works.
In a nutshell, The HC-SR04 Ultrasonic Distance Sensor is
1 – An Ultrasonic Transmitter – This transmits the ultrasonic sound pulses, it operates at 40 KHz
2 – An Ultrasonic Receiver – The receiver listens for the transmitted pulses. If it receives them it produces an output pulse whose width can be used to determine the distance the pulse travelled.
Components Sourcing (BOM)
A few components are needed for this simple gadget.
These components are easily accessible from Amazon, Ebay or Aliexpress.
BOM : Bill of materials
Step 2: Schematics
The Open source Schematic Capture & PCB Design Software Kicad is used.
Step 3: Pcb Design
Kicad is used to route the board.
Step 4: PCB Assembly
A few components are to be soldered for this gadget.
Be careful and patient.
Step 5: Arduino Sketch
The arduino sketch uses the famous NewPing library to read the distance from the sensor.
The NewPing Library is Open Source and very well documented.
Step 6: Arduino Sketch Flashing
The flashing of code will use the Arduino Uno itself as an ISP programmer.
Hopefully, the “ATTINY85 ISP Programmer Shield “ is used to flash the board.
Remark: Read the article “Yet Another ATTINY85 ISP Programmer Shield for Arduino”
Step 7: Enjoy
In this article we have gone over all the steps to produce a funny gadget that might be helpful.
