[Gmecm] Any USB developers out there?

[Bill Shaw]

Motorola has discontinued almost everything containing a BDLC,  says 
J1850 is loosing popularity.  The only thing they still have in the 
product line is a couple of HC12 variants with BDLC.  GM is going all 
CAN as of 2008.  Bit-banging looks like the only real alternative 
besides ELM for new devices,  and ELM is just a bit banging 
implementation itself.

Bill

Craig Moates wrote:
> Bill,
>
> This is in Cadsoft Eagle 4.16 (www.cadsoft.de), it should fit in the 
> 'Free' version but I haven't tried it that way.
>
> Agreed on the 68HC58, it is obsolete. But I've got a few hundred 
> laying around from another project so figured I'd try and make use of 
> it. Plus you can still get it from sources like www.newark.com I think 
> they have 700+ in stock at sub $4 each. Eventually it'll dry up in 
> terms of supply, and the design will need to be updated.
>
> Are there any updated chipsets which would handle all the VPW timing 
> and encoding including 4x? I've seen the line level stuff like the 
> MC33990, but you have to do all the pulewidth management at the micro 
> side. I think that would be a great way to go, but would put more 
> burden on the firmware development side. Maybe eventually, but for a 
> quick-hit, the 68HC58 should cut it. Open to other ideas though.
>
> Best regards,
> Craig Moates
>
>
> ----- Original Message ----- From: "Bill Shaw" <b.shaw at comcast.net>
> To: <gmecm at diy-efi.org>
> Sent: Thursday, December 21, 2006 7:32 AM
> Subject: Re: [Gmecm] Any USB developers out there?
>
>
>> Hi Craig,
>>
>> What schematic capture are you using for this?  The first problem I 
>> see is the 68hc58,  Freescale says it's obsolete and not recommended 
>> for new designs.
>>
>> Best,
>>
>> Bill
>>
>> Craig Moates wrote:
>>> Steve,
>>>
>>> I've put together an 'alternate' layout for USB-to-VPW. Feel free to 
>>> take a look. I have yet to stitch together all of the connections, 
>>> but given about an hour or so, it can be cleaned up and made to be 
>>> pretty tight. Check the readme.txt for comments.
>>>
>>> I just did it from scratch, based on the datasheets and takeoffs 
>>> from what I've done before. But it could be made to be pretty tight 
>>> and workable, and very low cost as well. It doesn't have integrated 
>>> USB in the micro, but on the other hand, it would be able to use 
>>> standard COM port protocols. You could set it up with a bootloader 
>>> as well to make it field updateable.
>>>
>>> Y'all are welcome to play however you like. I'm going to beat on it 
>>> some more and get all the connectivity together. Might even hit on 
>>> the firmware if I can find a spare day or two. Ha! Feel free to put 
>>> it in as part of the Wiki for the GMECM stuff. It's a work in 
>>> progress to be sure, but I figured I'd share what I had thus far.
>>>
>>> www.moates.net/projects/class2/
>>>
>>> Best regards,
>>> Craig Moates
>>>
>>>
>>> ----- Original Message ----- From: "Steve Ravet" <Steve.Ravet at arm.com>
>>> To: <gmecm at diy-efi.org>
>>> Sent: Sunday, November 19, 2006 11:41 PM
>>> Subject: RE: [Gmecm] Any USB developers out there?
>>>
>>>
>>>
>>>
>>>> -----Original Message-----
>>>> From: gmecm-bounces at diy-efi.org
>>>> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of Craig Moates
>>>> Sent: Thursday, November 09, 2006 11:51 AM
>>>> To: gmecm at diy-efi.org
>>>> Subject: Re: [Gmecm] Any USB developers out there?
>>>>
>>>> Steve,
>>>>
>>>> Definitely check the crystal and capacitor areas. Those are
>>>> ceramics you are using for the 18pF set? Check that it's set
>>>> up for 18pf on the xtal desired capacitance?
>>>
>>> The crystal is 20 MHz 18pf according to the digikey datasheet.  They're
>>> ceramic caps.
>>>
>>> I don't know what the problem with the crystal circuit is, but I 
>>> removed
>>> it and used a 4 MHz OSC instead, changing the firmware accordingly, and
>>> now it works.  I tried with and without the load resistor (on the
>>> crystal) but no change.  The demo board has an external load resistor
>>> but the data sheet shows a resistor internal to the part.
>>>
>>> I decided that I want USB power after all so I can reflash the PIC
>>> without external power.  You mentioned the circuit you use but I can't
>>> find the note now.  What is it?
>>>
>>> Craig, what do you use for schematic capture and PCB layout?
>>>
>>> Maybe there'll be a USB <-> VPW project working by Christmas now...
>>>
>>> thanks for the suggestions everyone,
>>>
>>> --steve