Electronic Horn System📣

This document describes the development of an electronic horn (E-Horn) for an automotive application. The E-Horn developed is for 4 wheeler applications but can be easily tweaked for 2 wheeler automotive applications. The design has been proven for 1 million cycles of Power ON and OFF for the required sound level (110 dB).

Purpose

• Mechanical horns have a typical lifetime of 2 years and low cost. The most common reason for failure of mechanical horns has been the burning of the coil because of high current.
• In addition, mechanical switches may develop carbon contact issues due to frequent switching.
• To address this issues and increase the lifetime of the horn, a precise frequency control is needed.
• To generate a precise frequency we chose the AVR family MCU with precise clocking source for the MCU. The low-cost target was met using the Value Line series of AVR.
• A temperature sensor is used to monitor coil tmeprature.
• To power up the MCU, a very reliable TI TPS79801 voltage regulator of 3.3 V was used. The TPS79801-Q1 has a wide input range up to 50 V, which suits 12-V automotive batteries as far as input transients.
• The thermal management of the volatage regulator is supported by thermal PAD under the chip.

Schematic Diagram

Working Principle

Watch youTube video to understand mechanical horn in details

Code Structure

• Electronic Horn System
  • include
    • GPIO.h
    • ADC.h
    • PWM.h
    • LCD.h
  • source
    • main.c
    • GPIO.c
    • PWM.c
    • ADC.c
    • ISRs.c
    • LCD.c
  • bin
  • obj
  • README.md
  • LICENSE.md

Must Read

Followings point shall be checked before the start of simulation

• All the buttons label are mentioned below the button and shall be in off condition.
• Status of the simulaion can be seen on LCD screen
• Analog value(Temperature sensor) only get updated when intrrupt buttons are pressed.
• Horn will blow only when horn button is pressed, When ignition is ON
• Potentiometer is used instead of temperature sensor.
• As there is not seperate hardware/filter is used for buttons so software debouncing is used
• Callibration is only possisble when engine is OFF.

License

This library is distributed under the MIT license found in the LICENSE file.