[Gmecm] Any USB developers out there?

[Steve Ravet]

> -----Original Message-----
> From: gmecm-bounces at diy-efi.org 
> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of Jay Shroff
> Sent: Thursday, December 21, 2006 12:29 PM
> To: gmecm at diy-efi.org
> Subject: RE: [Gmecm] Any USB developers out there?
> 
> > > Bill, I've been meaning to ask you about this. BDLC is one thing, 
> > > it> doesn't include a line driver and it doesn't do block 
> transfers 
> > > or 4x> mode. 68hc58 is a DLC, and if you go to 
> freescale.com and put 
> > > xc68hc58> into the search field you come up to a page with 4 DLC 
> > > parts that say> active, and in fact have all been transitioned to 
> > > ROHS. I'm not sure> that it is obsolete, given that it's the only 
> > > choice for PCM and for> reflashing equipment, since it 
> has support 
> > > for blocks and 4x.> > --steve> Hi Steve,
>  
> Do you have any doc's/Spec's on what you mean by blocks, I 
> have played around with a J1850 implementation and getting 4x 
> is not that difficult, but not sure what you mean by blocks.

Take a look at the 68hc58 spec on the gmecm page.  Normal J1850 messages
have a maximum length of ?? (100 bytes or so?).  Can't recall exactly.
Block mode does away with that and allows the transmitter to send as
many bytes as it wants.  Block and 4x are used together for reflashing,
to speed it up.

Having done this board I think bit banging may be a better solution,
certainly cheaper, although more work up front in the firmware.

--steve