Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

MEmento Final Presentation


Published on

Have you ever had that feeling of not remembering if you locked the front door? Or perhaps caught up in the rush of the situation, you were locked out without the house keys.

More info on our blogpost:
and our Github:

Published in: Engineering
  • Be the first to comment

MEmento Final Presentation

  1. 1. MEmento - Final Presentation Cervelli - De Luca - Di Maggio
  2. 2. Ever forgot to lock your door? MEmento is here to help you avoid such unpleasant situations! Or to take the keys?
  3. 3. Finally a Twitter notification reminds the user to lock the door In order to stop the alert, the user has to bring the FOB on his keyring near the RFID reader next to the keyhole If he is actually leaving, a sound alert starts playing (emulated via led) A keys-reminder system Through a magnetic switch, we are able to detect if the user is leaving
  4. 4. Powered by ● STM DISCO-L475VG-IOT01A ○ One of STM’s finest pieces of hardware ○ Enabled with low-power wireless, BLE, NFC, SubGHz, Wi-Fi ○ Perfect for developing cloud-based IoT applications ● ARM Mbed OS ○ Provides API preventing IoT developers from reinventing the wheel ● AWS IoT Core ○ Easily integrated with our STM board ● Twitter ○ Used to notify the user on his mobile devices
  5. 5. Hardware components We have to connect to our STM board a magnetic switch, used to detect if the door is open or closed (it simply checks whether the electric current passes or not), and an MFRC522 RFID reader. The MFRC522 also comes with a keyholder tag, which was simply perfect for the user experience we designed.
  6. 6. Why not NFC? Currently ARM Mbed hasn’t implemented any API to support its use as an initiator in the NFC protocol. All it can do as of now is to emulate a tag, or to act as an EEPROM, so it’s not viable for our use case. Source: Mbed Office Hours with Donatien Garnier
  7. 7. AWS IoT Core MQTT connection (1/3) pc.printf("Connecting to host %s:%d ...rn", MQTT_SERVER_HOST_NAME, MQTT_SERVER_PORT); { mqttNetwork = new MQTTNetwork(network); int rc = mqttNetwork->connect(MQTT_SERVER_HOST_NAME, MQTT_SERVER_PORT, SSL_CA_PEM, SSL_CLIENT_CERT_PEM, SSL_CLIENT_PRIVATE_KEY_PEM); if (rc != MQTT::SUCCESS){ const int MAX_TLS_ERROR_CODE = -0x1000; // Network error if((MAX_TLS_ERROR_CODE < rc) && (rc < 0)) { pc.printf("ERROR from MQTTNetwork connect is %d.", rc); } // TLS error - mbedTLS error codes starts from -0x1000 to -0x8000.
  8. 8. AWS IoT Core MQTT connection (2/3) if(rc <= MAX_TLS_ERROR_CODE) { const int buf_size = 256; char *buf = new char[buf_size]; mbedtls_strerror(rc, buf, buf_size); pc.printf("TLS ERROR (%d) : %srn", rc, buf); } return -1; } } pc.printf("Connection established.rn"); pc.printf("rn");
  9. 9. AWS IoT Core MQTT connection (3/3) pc.printf("MQTT client is trying to connect the server ...rn"); { MQTTPacket_connectData data = MQTTPacket_connectData_initializer; data.MQTTVersion = 3; data.clientID.cstring = (char *)MQTT_CLIENT_ID; data.username.cstring = (char *)MQTT_USERNAME; data.password.cstring = (char *)MQTT_PASSWORD; mqttClient = new MQTT::Client<MQTTNetwork, Countdown>(*mqttNetwork); int rc = mqttClient->connect(data); if (rc != MQTT::SUCCESS) { pc.printf("ERROR: rc from MQTT connect is %drn", rc); return -1; } } pc.printf("Client connected.rn"); pc.printf("rn");
  10. 10. Door checking, starting alert and firing MQTT message // IF DOOR IS OPEN if ( == 1) { static unsigned short id = 0; char payload[] = "{ "payload": TWITTER-ID-GOES-HERE }"; //START LED ALERT (A SOUND ALERT COULD BE IMPLEMENTED AS WELL) led = 1; MQTT::Message message; message.retained = false; message.dup = false; const size_t buf_size = 100; char *buf = new char[buf_size]; message.payload = (void*)buf; message.qos = MQTT::QOS0; = id++; int ret = snprintf(buf, buf_size, "%s", payload); if(ret < 0) { pc.printf("ERROR: snprintf() returns %d.", ret); continue; } message.payloadlen = ret;
  11. 11. Shutting down the alert with MFRC 522 // Wait for the RFID tag to stop the alert pc.printf("Wait alert to stoprn"); while(! (RfChip.PICC_IsNewCardPresent() || stopAlarm)) { wait(0.5); } pc.printf("Alert stoppedrn"); // Reset led to off state and stopAlarm to false led = 0; stopAlarm = false; // Wait until the door is closed before restarting the cycle pc.printf("Wait for door to be closed againrn"); while( == 1) { wait(0.5); }
  12. 12. Send Twitter message with AWS Lambda The MQTT message publishing acts as a trigger to an AWS Lambda function. We choose to use AWS Lambda because it allows us to run the “lambda_handler” function when the MQTT request is received and take is payload, without configuring any server. For our purposes AWS services are provided for free and we were able to write our function in Python, using a Twitter API library.
  13. 13. AWS Lambda Notification Code
  14. 14. Thank you! Contacts: Gabriele Cervelli gabriele-cervelli-88406b181 polyc Giovanni De Luca gdlroma jotaro-sama Antonino Di Maggio antonino-di-maggio-216479143 antoninus96 Blogpost: Code on GitHub: