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Embedded World 2018

Arduino shields provide CAN FD connectivity

The ATA6563 click is a tiny module, which connects an Arduino Uno to CAN FD networks. The MCP2517FD click provides not just the CAN FD transceiver but also an external CAN FD controller.

The ATA6563 click links the Arduino on-board CAN port to the CAN bus-lines (Photo: Mikroelektronika)

Unfortunately, Arduino products do not provide direct connectivity to CAN FD networks. The TxD and RxD pins of on-chip CAN module are accessible at the I/O ports. But there is no CAN transceiver. Therefore, Mikroelektronika offers the ATA6563 click module carrying the ATA6563 high-speed CAN transceiver. The product is designed to run on a 5-V power supply and can be clicked on an Arduino shield with a Mikrobus socket. It communicates with the target micro-controller via the UART interface with additional functionality provided by the AN pin on the Mikrobus interface.

The on-module ATA6563 high-speed CAN transceiver provides an interface between a CAN protocol controller and the CAN_H and the CAN_L bus lines. It is qualified for bit-rates up to 5 Mbit/s. The transceiver offers improved electromagnetic compatibility (EMC) and improved electrostatic discharge (ESD) performance.

The MCP2517FD click features an external CAN FD controller and a CAN high-speed transceiver (Photo: Mikroelektronika)

The MCP2517FD click is a similar tiny module, which can be mounted on an Arduino shield. It can be powered with 3,3 V or 5 V. The module is equipped with the MCP2517FD external CAN FD controller and the ATA6563 CAN transceiver from Microchip. The module provides a 9-pin D-sub connector with CiA-compliant pin assignment. It communicates with the target micro-controller through the SPI interface with additional functionality provided by Mikrobus pins. Of course, the implemented CAN FD controller supports also both Classical CAN frame formats with 11-bit and 29-bit identifiers.


CAN high-speed transceiver
In the past, most of the CAN high-speed transceivers were qualified for bit-rates of 1 Mbit/s. They met the requirements of the legacy ISO 11898-2 standard. With the introduction of the CAN FD protocol supporting higher bit-rates, it was necessary to use transceiver qualified for more than 1 Mbit/s. The new ISO standard for CAN transceivers, ISO 11898-2:2016, specifies parameters for transceivers supporting 2 Mbit/s and 5 Mbit/s. They should not be named as CAN FD transceivers, because they do not know anything about the CAN FD protocol. This is not really true, because there are CAN transceivers implementing partly the CAN data link layer. This is needed, when they feature the selective wake-up functionality as specified in ISO 11898-2:2016.
The ATA6563 transceiver by Microchip (originally developed by Atmel and after the acquisition now part of the Microchip portfolio) features low-power mode and is qualified for bit-rates up to 5 Mbit/s. This CAN transceiver can be connected directly to the micro-controller supply voltage. This allows adjusting the signal levels of the TxD, RxD, and STBY pins to the I/O level (3,3 V of 5 V) of the MCU.

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