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Disconnecting/Hanging an Incoming Call in SIM808 GSM/GPRS/GPS Modem with ATmega32

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In this project, we will learn Disconnecting/Hanging an Incoming Call in SIM808 GSM/GPRS/GPS Modem with AVR ATmega32 Microcontroller. Here, we will disconnect an incoming call to the SIM808 GSM/GPRS/GPS modem with ATmega32 microcontroller and we will display the status of the Disconnection of Incoming Call in a 16X2 alphanumeric LCD.

When the SIM808 GSM/GPRS/GPS modem power is turned on, the ATmega32 microcontroller reads the initial status data sent by the SIM808 GSM/GPRS/GPS modem through USART protocol. After reading the status data, the ATmega32 microcontroller processes the SIM900 GSM/GPRS modem status data and displays the status of the modem and SIM in the alphanumeric LCD. If SIM card is not present, then "Plz Insert SIM" is displayed, if SIM card is present and modem is ready, then "SIM900 is Ready" is displayed and for other conditions, "SIM900 Error" is displayed in the alphanumeric LCD.

Now, when the SIM808 GSM/GPRS/GPS modem is ready and it gets an incoming call, the SIM808 GSM/GPRS/GPS modem sends "RING" string to the ATmega32 microcontroller for each ring it receives. The ATmega32 microcontroller will read the "RING" string and it will count the number of ring. On reading the 1st "RING" string, "Incoming Call" is displayed in the 16X2 alphanumeric LCD. After 4 ring, the ATmega32 microcontroller will send "ATH" AT command(ATH command is used to disconnect any call) to the SIM808 GSM/GPRS/GPS modem. In response to the AT command, the SIM808 GSM/GPRS/GPS modem will a send a response to the ATmega32 microcontroller. The ATmega32 microcontroller will analyse the response and accordingly it will display the status of Call disconnection in the alphanumeric LCD. The alphanumeric LCD will display "Call Disconnected" if SIM808 GSM/GPRS/GPS modem disconnects the incoming call or it will display "Error" if AT command is not executed properly or "Other Error" for other types of error in the SIM808 GSM/GPRS/GPS modem. 

Now, dial the number that is there in the SIM808 GSM/GPRS/GPS modem SIM tray and see whether call gets disconnected after 4 ring or not.

Softwares Required

Hardwares Required

Name Quantity
AVR Trainer Board-100 with ATmega32 1pc
AVR USB Programmer 1pc
SIM808 GSM/GPRS/GPS Modem 1pc
3.5mm Audio Socket Board with Head Phone 1pc
RG1602A 16X2 Alphanumeric LCD Green 1pc
12V, 2A SMPS Adaptor 1pc
10 to 10 FRC Female to Female Connector 2pc
1 to 1 Connector-Female to Female 5pc

Circuit Diagram



Disconnecting/Hanging an Incoming Call in SIM808 GSM/GPRS/GPS Modem with ATmega32
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