The project “Arduino and GSM Based Automatic Answering Machine” is designed to answer the phone call with prerecorded message when we are unable to attain call.
Sometime in this busy world we might not be able to attain the phone call due to several reasons (generally when we are in bathroom or watching movie in cinema or forget mobile in home). These calls might be important i.e. call might be from office or business call which cannot be ignored. Thus, the project posted here receive the call after three rings and play the pre-recoded message which you had already recoded and saved in ISD1820 voice module.
Circuit Description of Arduino and GSM Based Automatic Answering Machine
The circuit of Arduino and GSM Based Automatic Answering Machine is shown in figure 1. This project is built around easily available electronic components like Arduino Uno, GSM module and ISD1820 Voice module. The main or controlling part of this system is Arduino Uno Board. Arduino Uno board is basically a prototype platform consisting ATmega328 microcontroller. The working of the project Arduino and GSM Based Automatic Answering Machine is quite straight forward, and on with little knowledge in arduino can understand easily.
ISD1820 is a voice module which is designed for audio message record and play back. The module has on board non-volatile memory for storing voice recording, Recoding time depends upon the quality of voice and is of 8 second to 20 second. Here we had listed some specification of ISD1820 voice module.
- On board non-volatile memory for storing massage for long time without supplying power supply continuously.
- In built microphone for recording audio message.
- Three individual push buttons switch for recording, edge trigger play and level trigger play.
- Single as well as loop play option.
- Loudspeaker can be directly connected to board thus no further need of amplifier and driver circuit.
- Operating voltage: 3V – 5V.
GSM Module: SIM900 GSM module is preferred for this project for communication between accident detector and alert system and mobile phone. It is basically tri-band work on various frequency range (EGSM 900 MHz, DSC 1800 MHz and PCS 1900 MHz). In order to make communication between GSM mobile and arduino uno we had used Tx pin and Rx pin of GSM module and digital pin 9 and 10 of arduino pin. Tx pin and Rx pin of GSM module is connected digital pin 9 and pin 10 or arduino respectively as shown in circuit diagram. GSM module is powered with 12V dc supply.
The speaker pin of ISD1820 is connected to microphone pin of GSM module to send the recorded message to GSM module when GSM module detect incoming call. Similarly P-E (E-play) pin connected to digital 8 pin of arduino for communication.
The working of the project Arduino and GSM Based Automatic Answering Machine can be summarized in 3 points below:
- Connect the component as shown in circuit diagram and give the power supply (12 volt to GSM module, 9V to arduino and 5V to ISD1820 voice module). Wait for approx. 1 minute after inserting SIM card to GSM module for establish connection between network provider and GSM module. The LED flashing in every 3 second mounted on GSM module indicates GSM module established the connection with network.
- Record the message (max. length of 10 seconds) by pressing REC. button on ISD1820 and program the arduino with the code given below.
- Now your device “Arduino and GSM Based Automatic Answering Machine” is ready to use.
Software: The software of Arduino and GSM Based Automatic Answering Machine is written in arduino programming language and compiled using arduino IDE. You can directly download use the code. Before proceeding to burning code in arduino you have to download GSM library for arduino and put it into arduino library folder. The folder of software contains complete software code for Arduino and GSM Based Automatic Answering Machine and GSM library.
PARTS LIST USED IN THE PROJECT ARE LISTED BELOW
- Arduino Uno Board
- GSM Module – Flyscale SIM900A
- ISD 1820 Voice Module
- Connecting Wires
- Power Supply for modules