[Ovmsdev] Can I use a 2-wire canbus with a single-wire bus?

[Craig Leres]

There aren't very many interesting can pids on the high speed (2-wire) 
can bus in my Cadillac. For example if I capture frames while using a 
tech2 to look at tpms data, nothing looks like tpms data. Since the 
tech2 has both 1 and 2 wire can interfaces I want to start looking at 
the low speed single wire bus. (Maybe it's just that a "little battery" 
car first sold in 2008 does things on the low speed bus that newer EVs 
do on a/the high-speed bus?)

My assumption is that the MCP2515 doesn't care about the physical layer 
as long as the speed is set correctly so my initial thought was to just 
back a 2-wire transceiver chip up to a single wire one, e.g. the MCP2515 
and MC33897. But a friend pointed me at a block post where this guy is 
using a 2-wire sparcfun shield to snoop a single wire bus:

 
https://blog.mikejmcguire.com/2017/02/20/eavesdropping-on-the-single-wire-can-bus-part-4-gmlan-holden-ve-commodore-swcan/

He basically just ties can L to ground and can H to the bus. I also 
found a copy of the can single wire spec (J2411-2000) and it seems 
2-wire is 2V differential and single wire is 0-4V so I guess I see how 
this might possibly work (depending on how the bus i/o pins are designed).

Anyway, is it safe for me to do this with one of the SN65HVD233D 
transceivers used in the ovms V3 module?

		Craig