Falk Salewski wrote:
> Thanks for the reply!
>
> I realized four 8bit counters in the CPLD and just want to send this
> information (4Byte) via the CAN-Bus, lets say all 100ms. Right know I am not
> thinking wether this is the optimal solution but if it is possible without
> an aditional uC (Project at university)
> I will have a look if I can store enough information in the CPLD for the
> initialization of the SJA1000 chip...

First, find some working SJA1000 software, in any uC family will do.
Search also for the 82C200, which is the older sibling
of the SJA1000. Philips will probably have some 80C51 examples.
Then, look to move that function into the CPLD.
To give your tutor some real numbers, assemble JUST the code for
init & simple Echo, and print the LINK MAP, to show how much RAM and
CODE space is needed. [eg it might be 5 bytes of RAM, and 275 Bytes of Code]

I think I saw recently a CAN controller [SJA1000 like], that could
as an option, 'wake up' in simple peripheral mode, IIRC using a Serial
EE to config. That would be another 'no code' alternative.

-jg

>
> FalkS.
>
> "Jim Granville" <[email protected]> schrieb im Newsbeitrag
> news:mBCqd.13010$[email protected]..
>
>>Falk Salewski wrote:
>>
>>>Thank you very much for your reply.
>>>
>>>However what I am looking for is how difficult is it to connect a CPLD to
>>>a CAN-controller chip like the SJA1000
>>>http://www-eu3.semiconductors.com/pip/SJA1000.html
>>>and how many of the CPLD resources it takes to initialize/communicate
>>>with this CAN-controller.
>>
>> You'll need to setup the registers [either a rom in the CPLD, or
>>a Serial EE holding the init values, to BUS], and then be able to poll
>>messages, and manage TX packets (which come from where ?).
>>
>> All of these are not CPLD-centric tasks, so why not use a small uC
>>instead - or even better, choose a uC with CAN on chip ?
>> If you have the XC2C256 there already, needing > 128 MC for other tasks,
>>then you could use a small portion, for SPI-SJA1000 bridge, and then use a
>>small SPI uC for the CAN manager/init.
>> Philips LPC9xx or Silicon Labs C8051F33x series would do this, in tiny
>>11-20pin packages.
>> -jg
>>
>>
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