A simple project demonstrating an IoT approach to vehicle tracking. The project has 3 software components: node devices, the edge device, and the web client. Node devices notify the edge device of new data via BLE GATT, which is then fetched by the edge device and cached locally in a redis database. Data is then pushed to the cloud (AWS) via MQTT. When AWS receives data via MQTT, it is stored in a dynamodb for later retreival. Finally, this data is pulled by the web client and presented as both a table of values and a path on google maps (for GPS data).
This repository is specifically for node device firmware. For other software components, please see their corresponding repositories (in the Other repositories section below).
There are currently 2 node device implementations. One using an ESP32 with a GPS module for geo tracking, and a second using an Arduino with a BLE module (HM-10) and an IMU module (Sparkfun MPU-9250). Code for each node be found in the esp_ble_serial and arduino_accel directories respectively.
The ESP32 GPS node utilises a custom Global Top GPS receiver module, an ESP32 module, and its built
in Bluetooth BLE tranciever hardware. Communications with the GPS module are via a unidirectional
UART connection, with the ESP32 using a simple ring buffer for incoming data. NMEA data from the
GPS module is then communicated to the edge device using a UART like protocol implemented on top of
BLE GATT. NMEA data is broken into blocks of length ESP_GATT_MAX_ATTR_LEN and set as the next
chunk of the message.
Most of the heavy lifting of the BLE GATT protocol is performed by the ESP BLE framework, with only minor things, such as fetching from the ring buffer and detecting when a client connects or disconnects, being performed within the .ino file.
The Arduino IMU node sports a 9DOF Sparkfun IMU sensor (MPU-9250) and an HM-10 based Jaycar BLE module, as well as an Arduino Nano (although any Arduino device could theoretically be used). The MPU-9250 is capable of measureing acceleration (accelerometer), relative direction changes (gyroscope) and 3D magnetic field strength (magnetometer).
Data is collected from the IMU over I2C, using the Sparkfun provided MPU-9250 library. If an edge device is connected via BLE (as indicated by the BLE module state pin), then collected data is formatted in plain text and transmitted to the BLE module every 200 milliseconds. The BLE module receives the data and transmits it via BLE to the connected edge device, in a smiliar fashion to the ESP32 node above.
For more details, take a look at the corresponding report