SparkFun Forums

[jens_munk]

Hi,

I would like to use an Arduino Ethernet board with a CAN-BUS Shield to make a simple Ethernet <-> CAN gateway. However, it seems like I am running into troubles with the SPI. Is it realistic to use another SS for the CAN board or is this idea just beyond the Arduino world?

Thanks,

Jens.

[Polux rsv]

If the CAN traffic is heavy and/or transmit speed is high, you will reach the limit. Not the SPI transmission speed, but the total handling speed.
Why not use a micro which has integrated CAN and ethernet. I use LPC1769, which is a Cortex M3 @ 120MHz on a LPCXpresso board. With this board, you only need to add a CAN transceiver. Everything ethernet is already onboard, except the connector.
You could also try Mbed.
Many STM32 evaluation boards also have everything onboard.

Angelo

[gilgoe]

Is using Mbed really helps in this situation?

[stevech]

Mbed's TCP/IP stack is improving but still buggy.

Any Atmel AVR with SPI could mate with a WizNet full module (not chipset), and your TCP/IP/ICMP/ARP is all off-loaded, for 5-8 concurrent sockets. Moreover, the packet buffers are off-loaded - and with small RAM AVRs, these features are essential.

CAN is "just" 150Kbps as I recall, in common vehicular use. Not a big load. Its stack can be big and complicated though.

The LPCXpresso boards are good for a one-of project. But look at the on-board vs. off-loaded TCP/IP. It drives the software architecture due to the packet events.