Disconnecting/Hanging an Incoming Call in SIM900 GSM/GPRS Modem with AVR ATmega16 Microcontroller

Disconnecting/Hanging an Incoming Call in SIM900 GSM/GPRS Modem with ATmega16

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In this project, we will learn Disconnecting/Hanging an Incoming Call in SIM900 GSM/GPRS Modem with AVR ATmega16 Microcontroller. Here, we will disconnect an incoming call to the SIM900 GSM/GPRS modem with ATmega16 microcontroller and we will display the status of the Disconnection of Incoming Call in a 16X2 alphanumeric LCD.

When the SIM900 GSM/GPRS modem power is turned on, the ATmega16 microcontroller reads the initial status data sent by the SIM900 GSM/GPRS modem through USART protocol. After reading the status data, the ATmega16 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 SIM900 GSM/GPRS modem is ready and it gets an incoming call, the SIM900 GSM/GPRS modem sends "RING" string to the ATmega16 microcontroller for each ring it receives. The ATmega16 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 ATmega16 microcontroller will send "ATH" AT command(ATH command is used to disconnect any call) to the SIM900 GSM/GPRS modem. In response to the AT command, the SIM900 GSM/GPRS modem will a send a response to the ATmega16 microcontroller. The ATmega16 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 SIM900 GSM/GPRS 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 SIM900 GSM/GPRS modem.

Now, dial the number that is there in the SIM900 GSM/GPRS 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 ATmega16	1pc
AVR USB Programmer	1pc
SIM 900 GSM/GPRS 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	9pc