Re: MCP2515 implementation is slow

David Jander
2014-11-27T07:33:46Z

On Tue, 25 Nov 2014 16:19:33 +0000
"Pankajkumar Misra (RBEI/EEA2)" <Pankaj.Kumar@in.bosch.com> wrote:

> I have compiled MCP251x.c kernel driver module for Olimex A20-Olinuxino
> Micro.
>
> The device is working fine for one frame at a time at 500ms. If I send two
> or more frame at the same time, CAN is going to bus-off due to overrun
> errors. Even if I send one frame at faster rate say, 100ms,results in
> bus-off.

I tend to think there is something other wrong with your setup. Maybe you are
missing bus-termination/biasing? Chip-clock?
The device should never go in bus-off mode if there are RX-overruns. If it
goes into bus-off, there is something wrong in the hardware.

> I am communicating with module with ip commands, cansend & candump.
> Also my SPI module is working only at 250K baud, not any other baud.

We use a MCP2515 with this driver at 250kbit/s receiving back-to-back messages
without loss on a i.MX51. Please note, that it won't work reliably at any
higher bitrate and system load is quite high.

The MCP2515 is a very bad design, but the driver performance has improved a lot
since spi-bitbang started using a kthread instead of a work-queue.

> Any suggestions.
>
> Best Regards,
> Pankaj
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Best regards,

--
David Jander
Protonic Holland.