1.1 Mission/Theme This document is an information report and intended to provide an overview of the Clock Extension Peripheral Interface (CXPI) protocol. 1.2 Overview This document describes the features and functions of the CXPI protocol. The CXPI protocol provides some selected features of the Controller Area Network (CAN) protocol implemented on a UART-based data link for mainly HMI (Human Machine Interface) of road vehicles electric systems. 1.3 Relationship to JASO D015 CXPI Specification This information report is a description of the CXPI protocol, which is specified in the JASO D015 CXPI document published by JASO. The JASO D015 CXPI specification is the normative reference for the CXPI protocol. The CXPI specification is maintained by JSAE (Society of Automotive Engineers of Japan, Inc.). This information report does not supersede any information contained in the JASO D015 CXPI specification. It has the sole purpose of providing textual description and graphical illustrations to ease reading and interpretation of the CXPI protocol.