5 - MIT Wake-up Call System Ruby Pai Surapap Rayanakorn...

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MIT Wake-up Call System Ruby Pai Surapap Rayanakorn Audrey Roy
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Features ± Security PIN - Each user is assigned a PIN associated with his telephone number - When a user calls in, the system verifies his PIN before allowing the user to proceed to the menu. ± Menu Options - Request wakeup call - Cancel requested wakeup call - Check scheduled requests for his phone number - Hear the system time to synchronize with the user’s watch
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Basic Block Diagram
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Phone Interface Functions ± detect incoming call ± pick up/hang up phone ± dial numbers ± detect/interpret dialed numbers ± send prerecorded audio over phone line
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Phone Terminology ± loop : twisted wire pair connection between phone and central office ± individual wires: tip and ring
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Phone Dialing ± Two types: pulse and tone ± Our system uses tone ² each digit dialed generates two tones (frequencies) ² also called dual tone multi frequency ( DTMF )
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Phone Interface: MH88437 ± Data Access Arrangement Chip ± provides complete interface between audio/data transmission equipment and phone line ± Tip and Ring connections ± Functions: ² detect incoming call ² pick up/hang up phone ² send prerecorded audio
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Phone Interface: MT8889C ± DTMF transceiver ² convert binary digit to DTMF (outgoing call) ² convert DTMF to binary digit (incoming data)
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Audio Overview ± Record Mode: - Takes audio input from microphone - Samples the analog input - Store the samples in RAM - Store the samples in ROM by creating specification file from data in RAM ± Playback Mode: - Retrieves digitized samples from ROM upon requests from audio major FSM - Converts it to analog outputs - Amplifies and sends to the speaker
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This note was uploaded on 07/21/2009 for the course EECS 6.111 taught by Professor Prof.ananthachandrakasan during the Spring '04 term at MIT.

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5 - MIT Wake-up Call System Ruby Pai Surapap Rayanakorn...

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