بسم الله الرحمن الرحيم
Step 1: Introduction
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.
- 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.
Step 7: LEDs Array Board
A simple array of SMD RED LEDs.
Step 8: PCBs Assembly
Simple boards means simple assembly.
Step 9: Coding
The Code uses the fantastic RadioHead library.
Step 10: Enjoy
A 19 seconds Video is joined to this article.
الحمد لله رب العالمين