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Oliver Hartkopp schrieb:
> Wolfgang Grandegger wrote:
>> On 09/08/2009 03:10 PM, Oliver Hartkopp wrote:
>>> Sebastian Haas wrote:
>> What is "m16"?
>
> It's a M16C processor that sits in the ems_usb hardware sometimes.
>
> There are two possible CPUs in the USB adapter:
>
> +static struct usb_device_id ems_usb_table[] = {
> + {USB_DEVICE(USB_CPCUSB_VENDOR_ID, USB_CPCUSB_M16C_PRODUCT_ID)},
> + {USB_DEVICE(USB_CPCUSB_VENDOR_ID, USB_CPCUSB_LPC2119_PRODUCT_ID)},
> + {} /* Terminating entry */
> +};
>
>
> Btw. the SJA1000 is indeed a LPC2119 that has two CAN controllers/makros with
> a SJA1000 layout onboard.
>
> So we could also use 'lpc2119_bittiming_const' which would probably add some
> confusion as everything else looks like a SJA1000 ;-)
The CPC-USB/ARM7 expect SJA1000 parameters. The CPC-USB/M16C expect M16C
parameters.
>> Also I don't like that we introduce another set of SJA1000 register
>> definitions and offsets. Furthermore, there are many UBS based SJA1000
>> devices on the market and we should think if we could provide a common
>> interface for these, if feasible. E.g. sja1000_usb.c similar to sja1000.c.
>>
>
> The problem is, that each of them defines a proprietary struct for the usb
> communication as they are always talking to 'helper' CPUs and not directly to
> the SJA1000. So a sja1000_usb.c will never become true ...
There are some cheap USB interfaces which use a FTDI directly connected
to the SJA1000. For these devices a common interface makes sense. But as
you already corrected recognized, most commercial USB/CAN interfaces use
more complex structure to squezze out the performance.
> This definition of 'struct CPC_SJA1000_PARAMS' might look superfluous but it
> isn't. It's just needed to build the correct message to *this* USB adapter.
Completely correct!
Cheers, Sebastian
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