RE: CAN bus for control, was Re: Honeywell thingy!!

["Dave McLaughlin" <dave@xxxxxxx>]

Hi James,

Blue LED's are so cool. My hall at night is lit up by a couple of these on
my interface panel for the boiler monitor.

The silicon for CAN bus can be had from Microchip (MCP2515, MCP2551),
Philips Semiconductor (SJA1000, PCA82C251) and others. The Kvaser site
list=
s
some the silicon vendors. The MCP2515 costs about =A33.00 and the same for
=
the
SJA1000. The 2 transceiver devices, the PCA82C251 and the MCP2551 are about
half this or less.

The MCP2515 has a high speed SPI interface that is easily hooked up to a
microcontroller such as the PIC or AVR etc. Being a serial interface, it
only requires 4 lines to provide control. This is the device I use on all
m=
y
modules.

The SJA1000 is a parallel port device. It is a multiplexed device with an 8
bit address and data bus on the same pins. A clever bit of address decoding
and you can use this on the PC's parallel port. In fact I designed my own
interface for such a use of this device. Computer Solutions also sell a PC
parallel port CAN bus interface with drivers for around the =A3120 mark.
Mo=
re
expensive than mine, but then their drivers are more complete than mine. If
you want I can supply the schematic and PCB layout for my design and a
simple driver written in Borland C++ Builder 4.0 if you want to have a go
a=
t
doing your own. Parts cost is about =A325 plus the PCB which I had made by
PCB-Pool and you actually end up with 4 of them for their minimum size run.

The devices above handle all the bus arbitration and error handling. All
yo=
u
need to do is read and stuff registers. Dead easy really. You could do it
all in software, and there is a site on the Web with Atmel AVR code to do
this, but this uses up valuable code space.

By the way, computer solutions also do a PCI and ISA based single channel
board for under the =A3200 mark, I think?


Regards
Dave...

---
Very funny Scotty, now beam down my clothes!!!
---


-----Original Message-----
From: James Derrick [mailto:james-ukha@xxxxxxx]
Sent: 04 November 2003 00:33
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Re: Honeywell Smartfit research and the start of a
generic interface (wish me luck!)


On Mon, 3 Nov 2003 23:15:15 -0000, you wrote:

I like the boiler controller- must add some blue LEDs to my h/w!

What's the CAN bus interface like to use? Is there any good (available
& cheap!) dedicated silicon out there to do the nasties such as
termination and arbitration please?

I suppose two PICs (one just as a bus interface) would be an option,
although some of the later chips seem to have hardware UARTs and the
like.

Sadly, the Kvaser CAN hardware was looking good right until I saw the
$800 price tag for the USB interfaces.

TTFN,

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