RE: Re: Guidance on AN82527 from Intel

All CAN devices must read on their Rx inputs what they send on their
outputs.  How else would they be able to do arbitration?

Also since the CAN message requires an dominant ACK bit put into the ACK
slot position by a receiving node you _always_ have to have two CAN nodes to
make it work.

When you are new to CAN the best and easiest way to get things rolling with
something like a CAN232 or CANUSB from www.CANSUB.com Then your starting
point will be the correct bit rate, and transmitted messages that are
working correctly.

For example, (working from memory here) using a CANUSB as a serial port you
run Hyperterm or some other terminal software and send out something like an
S5<CR>  This sets the bit rate to 250kbps.  Then send an O<CR> to open the
port.   Now you can send a CAN message.  t222412345678<CR>  which sends
SID=222 with 4 bytes consisting of 23 45 67 89

If your AN82527 c/w 82C200 bus driver and two 120 Ohm termination resistors
should then receive this message assuming you have it configured for the
same bit rate.  With a scope you can look at the bus.  The message should
show up as a short burst.  If you see continual activity then the receive
part of your code isn't working.  Once you see the burst and can receive the
message then work on sending.  

The reason for doing it in that order is you start with a known message
structure and bit rate.  If you used two of your 82527s and had the bit rate
strange for both they might work but won't work with anything else.  Easier
to start with something that does work.

John Dammeyer


-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Mauricio
Gott
Sent: April-05-13 12:38 PM
To: [email protected]
Subject: [CANLIST] Re: Guidance on AN82527 from Intel

Sorry, i sent previous mail unfinished....

I was listing the steps from the datasheet that i followed:
Power Up
Init by the CPU
Upd data: start
Upd data bytes
Upd data: end

And then wrote  0x66 to register  0x11 for the transmision to start, but no
change in the TX0 and TX1 pins.
also checked if TxRqst changed or  Status bit  TXOK was set.
I dont want to send any specific communication, i just want to see if the
chip is able to send some pulses.
I know im missing something i just dont know what.

Any suggestions?
Thanks!

On Fri, Apr 5, 2013 at 1:28 PM, Mauricio Gott <[email protected]>
wrote:
> Hello!
> I have the task of checking the functionality of a reel of these IC 
> from intel, but have not worked with any CAN devices before so i 
> started from scratch.
> So far:
> I already defined my test method,
> I actually managed to read/ write correctly from all Control, Config, 
> and Message registers.
> Ive established all of these conditions listed on the datasheet for a
> transmission:
>
> Conditions required to transmit a data frame:
> 1) Init bit e 0
> 2) MsgVal bit e 1
> 3) direction e transmit
> 4) NewDat bit e 1
> 5) TxRqst e 1
>
> I also checked  the steps listed in "7.4 Host-CPU Handling of Message 
> Objects 1±14 (Direction = Transmit)":
> Power Up
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