COMMELL MPX-2515 - Manual (Page 3)

Commell MPX-2515 User’s Guide Rev 0100
Taiwan Commate Computer Inc. 3
1 Commell CAN Protocol
1.1 Introduction
This chapter defines the Commell CAN Protocol (CCANP), which is used to carry
CAN bus request packets from the USB host side to the USB device side (MPX-
2515). After the MPX-2515 firmware executed the request packet, the USB host side
application then retrieves the corresponding response packet from the MPX-2515
firmware.
The MPX-2515 firmware implements four endpoints to facilitate the CCANP and
therefore the host applications.
•
Endpoint 1 - The endpoint 1 implements the Bulk In transfers. The USB host
applications read endpoint 1 to return response packets.
•
Endpoint 2 - The endpoint 2 implements the Bulk Out transfers. The USB host
applications write request packets to this endpoint in order for the MPX-2515
firmware to carry on the requested command.
•
Endpoint 3 - Endpoint 3 implements the Interrupt In transfer. The USB host
applications can hence read the interrupt in packet at anytime in order to
realize some important status of the MPX-2515 firmware.
•
Endpoint 4 - In order to speed up the process on the received CAN messages,
an endpoint 4 was implemented to allow the USB host applications to read the
Firmware Message Buffer (FMB) at anytime. The MPX-2515 firmware
updates this buffer very often. The USB host applications determine the
received messages by checking the timestamp and other information
incorporated in the header of the FMB.
The following figure shows the transaction types and operation sequences of CCANP.