Bike Direction Indicator – مؤشر اتجاه الدراجة

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.


  • 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

“Coronavirus Covid-19” 1 Meter Keep Away Alarm Gadget

بسم الله الرحمن الرحيم

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.

GREEN LED lights if the measured distance from any object is greater than 120 cm.

RED LED blinks if the measured distance from any object is lower than 100 cm with a lovely (noisy) beep.

YELLOW LED blinks if the measured distance from any object is between [100,120 ] cm with a less noisy beep.


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.

A 15 seconds home made video shows a use case.

Need more information, put a comment.

الحمد لله رب العالمين

Yet Another ATTINY85 ISP Programmer Shield for Arduino

ISP Programmer

The ATTINY85 ISP Programmer Shield is designed to program easily the ATTiny85 µControllers.

The shield must be plugged to The Arduino Uno board.

The Arduino Uno is prepared to act as an “In Circuit Serial Programmer” (ICSP or ISP).

The shield has the following features:

  • A socket for ATTINY85 µControllers.
  • A socket for ATMEGA328 DIP µControllers.
  • A standard ICSP connector to program a large range of Microchip (ATMEL) µControllers .


Many articles on the internet explain in details how to design this simple ISP programmer.

In this article, I have gathered all the information in one place to be easily accessible and not confusing.

Step 1: PCB Design

Pcb design

The free open source software Kicad is used to design the PCB.

Step 2: Components Sourcing

Just a few components are needed for this simple project.

Step 3: PCB Manufacturing and Assembly

For quick PCB prototype and small-batch PCB production, The PCB is manufactured by JLCPcb.

Assembling the ISP shield is easy. Just a few components are soldered.

Be careful and patient.

Step 4: Preparing the Arduino Uno

The Arduino Uno must programmed with ArduinoISP sketch found in the examples section.

Step 5: Configuring the Arduino Uno

The Uno must be configured as “Arduino as ISP” in the Tools -> Programmer sub menu.

Step 6: Flashing the Bootloader to ATTINY85

This step serves only to flash the fuses of the ATTINY85 chip.

Be careful with setting fuses. “An internal 1 MHZ” is adequate for battery driven boards.

Step 7: Programming the ATTINY85 Sketch

Load your favorite sketcn and configure the arduino IDE for the right board, for instance the ATTINY85.

Click on the “Upload Using Programmer” under the “Sketch” menu to flash the chip.

Step 8: Enjoy

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