Development and characterization of a USB communication between two microcontrollers general purpose STM32 to analyze the digital IP in order to improve its performance

The objective that is proposed to achieve with this experience is to evaluate the characteristics, the performances and the limits of a USB communication between two evaluation boards belonging to the STM32G0 family via a USB type-C cable, highlighting anomalies and criticisms. The two evaluation boards have a USB type-C connector on board and they support the USB 2.0 version in full speed mode, i.e. they are able to exchange data between them at a speed of 12 Mbps. The activity was divided into several phases. The first one in which the knowledge on controllers and the USB protocol were acquired, the other one in which the skills to use ST’s software and boards were acquired. The last phase, the experimental one, is the one in which a criticism of the USB was stimulated in order to improve its digital design or the software usage. More specifically, at first a code was implemented that would allow to verify the correct communication between the host board and the device board. Subsequently, to put the digital IP under stress, the amount of data traffic exchanged between the two boards was increased and the used bandwidth has been evaluated. In this way it is possible to compare the theoretical limit of the data sent between two start of frames and the real one. This analysis was possible also thanks to a "Teledyne Lecroy Mercury T2C” protocol analyzer, that, located in series between the two boards, is able to spy on the USB data traffic that is exchanged and allows to evaluate, in addition to the used bandwidth, also other important parameters such as the transfer type, the various packets and their sizes and the possible errors that may occur.