[Ovmsdev] Help me get my first data item on the I3

[Michael Balzer]

Steve,

sorry, totally missed that. That's very unusual, haven't seen that 
before. I first thought maybe that's using CAN extended frame mode, but 
that's a totally different thing: it seems the i3 uses the *ISO-TP 
extended addressing scheme*.

Quoting from Wikipedia: https://en.wikipedia.org/wiki/ISO_15765-2

> ISO-TP can be operated with its own addressing as so-called/Extended 
> Addressing/or without address using only the CAN ID (so-called/Normal 
> Addressing/). Extended addressing uses the first data byte of each 
> frame as an additional element of the address, reducing the 
> application payload by one byte.

So it's standard frames, with just an additional byte inserted before 
the protocol, used to extend the CAN ID.

The OVMS poller doesn't support this yet.

But it shouldn't be hard to add support for this, as it basically just 
fills the first frame byte from the lower 8 bits of the TX and RX IDs, 
reduces the payload size by one byte and shifts the offsets by one. 
PollerSend() and PollerReceive() need to be extended for this, and 
poll_pid_t needs to be extended by an addressing scheme tag.

I'll have a look. Tell me if you'd like to take care of this.

Regards,
Michael


Am 13.12.20 um 09:58 schrieb Steve Davies:
>
>
> On Sat, 12 Dec 2020 at 17:28, Michael Balzer <dexter at expeedo.de 
> <mailto:dexter at expeedo.de>> wrote:
>
>     with log level verbose for canlog, you can simply activate CAN
>     logging via:
>
>     can log start monitor crtd
>
>     …that will log all frames, if that's too much, add a filter like this:
>
>     can log start monitor crtd 600-7ff
>
>
>
> To see what was happening I had to "log level verbose canlog-monitor"
>
> I see this being transmitted:
>
> V (62436161) canlog-monitor: 1607847148.142477 1T11 6F1 03 22 dd bc 00 
> 00 00 00
>
> There is no reply.
>
> The other app I looked at does this on the LM327 as setup before 
> sending the request:
>
> 2020-11-15 10:34:35.115 --> ATCEA07⏎ "extended address" 0x07
> 2020-11-15 10:34:35.127 <-- OK⏎⏎>
>
> Looking at the LM327 data sheet this configures an "extended address" 
> which is sent after the 0x6F1
>
> I'm not sure if that 0x03 in what OVMS is sending is that byte, and I 
> need to somehow replace it wih 07, or if I have to get another inserted?
>
> Perhaps this is old hat to those more experienced than me.
>
> From the data sheet and the trace it seems I'm also responsible to 
> customise the flow control messages :-
>
>
> 2020-11-15 10:34:35.129 --> ATFCSH6F1⏎ Flow control header
> 2020-11-15 10:34:35.141 <-- OK⏎⏎>
> 2020-11-15 10:34:35.143 --> ATFCSD07300800⏎ Flow control data
> 2020-11-15 10:34:35.156 <-- OK⏎⏎>
> 2020-11-15 10:34:35.157 --> ATFCSM1⏎ Flow control mode
> 2020-11-15 10:34:35.170 <-- OK⏎⏎>
>
> I think that comes down to a flow control being "06 F1 07 30 08 00"
>
> Here's the page in the LM327 to help understand what it does:
>
> image.png
>
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-- 
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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