The Pressure Fluctuation Monitoring System: Obtaining Accurately Synchronized Measurement From Multiple Sensors Using PTP And Bit-Banging I2C

Autor	Pham Huu Quang
Date	27. September 2021
Degree	Master
Topic	Development of a Pressure Fluctuation Monitoring System
Title	The Pressure Fluctuation Monitoring System: Obtaining Accurately Synchronized Measurement From Multiple Sensors Using PTP And Bit-Banging I2C
Abstract	As a part of the Shift2Rail research, this thesis attempt to build an encapsulated, easy to modify data collecting system for the EU-funded Digitalization and Automation (FR8RAIL IV) project to obtain accurately synchronized measurement from at least 300 sensor at a high sampling rate of 1000 Hz. This IoT-based solutions is applicable to any any data monitoring and collecting system, satisfies high requirements with low cost. A parallel bit-banging Inter-Integrated Circuit (I2 C) connection is used to accurately synchronized measurement from multiple sensors on each Microcontroller Unit (MCU). This not only reduce the cost of smart sensors, but also fit the model physically by grouping adjacent sensors and decrease the messages sent exponentially. For all boards to function in a time-homogeneous environment, we use Precision Time Protocol (PTP) and timestamping each measuring session and achieve sub-microsecond accuracy synchronized measurement regardless of the network routing. Several experiments on a test model consist of 2 NUCLEO-F767ZI boards and 1 Raspberry Pi4 Model B and on the actual system installed on a swap body container are conducted to make sure the system meets the project requirements. We find that the Parallel Bit-Banging I2 C works in all of its aspects and fill the thesis requirements. The dedicated PTP function, while fluctuates a lot, can self-correct and satisfy the project timing requirement. On the server side, a Raspberry Pi 4 can handle the communication easily while acting as a PTP server at the same time. The communication between all clients and the server is unencumbered with close to zero packet error rate. Overall, the outcome of the experiment is satisfying, and the solution matches the project requirements. With the evidence of our study and the experiments, we also give some suggestions for the future work to expand the practicality of the system.