Project JAGuar for FreeEMS

Andy's GM DIS centric hardware design! Also works as a fuel controller for EDIS and distributor applications.
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DeuceEFI
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Re: Project JAGuar for FreeEMS

Post by DeuceEFI »

TonyS wrote:Only other thing that I can see right now, is that the crystal is spec'd for 70C max. and I am not sure if you have a higher operating temperature environment spec as a target (85C?).
Good catch on that one, I will save the two I already have for another project :-)

I have added a crystal from the same manufacturer (same datasheet and load capacitors) with a -40C to 85C temperature range rather than the -10C to 70C temperature range of the one I originally chose to the BOM.
I also added a variety of crystal load capacitors so that I can test to see which one actually works.
TonyS wrote:One more little thing -
The schematic shows 22uF caps on the outputs of the regulator and the BOM calls out 47uF.
Almost missed this one while I was preparing the above reply... :o
The BOM has the correct value I wish to use, I have updated my schematics on my PC and have committed/pushed the KiCAD files just now and will have the schematic PDF up in a few minutes...

Thanks for all the input! 8-)
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DeuceEFI
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Re: Project JAGuar for FreeEMS

Post by DeuceEFI »

All files in my repository are up to date, I can almost smell the developer and etchant in the tanks :-)
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Re: Project JAGuar for FreeEMS

Post by TonyS »

Hey Andy,
I think that the Digikey P/N for the optos should be "PS299-1ACT-ND" (unless of course you really wanted 3,500 of them : ). Note that I did not check the BOM throuroughly for this sort of stuff, I was looking to find the specs for the opto and just find it SO easy to select the link to the Digikey P/N and pull up the datasheet.
Thanks,
Huff
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Fred
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Re: Project JAGuar for FreeEMS

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/me wishes that the forum had a "like" button!
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DeuceEFI
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Re: Project JAGuar for FreeEMS

Post by DeuceEFI »

TonyS wrote:I think that the Digikey P/N for the optos should be "PS299-1ACT-ND" (unless of course you really wanted 3,500 of them : ). Note that I did not check the BOM throuroughly for this sort of stuff, I was looking to find the specs for the opto and just find it SO easy to select the link to the Digikey P/N and pull up the datasheet.
Oops, yeah you are right, the Digikey P/N should be PS2911-1ACT-ND as I only need 2 for the board not 3500. Good catch, wow I should really stop looking up things at 2am, LOL.

Yeah, I like the hyperlinks as well, makes it easy for me and the next person when they want to check the Data Sheets. :-)

Any concerns before I etch a prototype board? I want to test out the USB setup to make sure the RX and TX circuits to the CPU are OK, unless someone else has already verified that the Ravage design is valid.

Thanks,
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Re: Project JAGuar for FreeEMS

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DeuceEFI wrote:Any concerns before I etch a prototype board? I want to test out the USB setup to make sure the RX and TX circuits to the CPU are OK, unless someone else has already verified that the Ravage design is valid.
No, not yet, Preston was supposed to, but the medication he's on keeps making him fall asleep all the time! LOL, poor bastard. If you want to assemble that and test, I'd be most pleased to get another data point on that part of the design! :-)

Fred.
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Re: Project JAGuar for FreeEMS

Post by lumpensack2003 »

Just looked over the schematics, here are the quirks I noted so far:

- all pull-down resistors of the CPU should be tied to CPU-GND (i.e. not Output-GND)
- upstream of the capacitors at the Vin pin of each voltage regulator there should be a schottky diode like SS12 or SS24. This will prevent bleeding current back to the cars cabling in case of negative spikes. I experienced input capacitance pretty useless without theses diodes.
- same reason with the 5V-USB: you should provide a possibility to stuff some series resistance (i.e. 5R1) or even FTDI's famous ferrite bead upstream of the capacitance. I once experienced connection sloppyness that instantly went away with 22R in the 5V-USB line. Ever since then a 0805 pattern inline 5V-USB is mandatory with my FT232RL applications.

Cheers,
GJ
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Re: Project JAGuar for FreeEMS

Post by Fred »

Lumpensack, why do you say "or even FTDI's famous ferrite bead" ie, why "or even"? Do you feel that it's inferior to a resistor? I'm curious!

Good catch on the pull downs!

Fred.
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DeuceEFI
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Re: Project JAGuar for FreeEMS

Post by DeuceEFI »

lumpensack2003 wrote:Just looked over the schematics, here are the quirks I noted so far:

- all pull-down resistors of the CPU should be tied to CPU-GND (i.e. not Output-GND)
- upstream of the capacitors at the Vin pin of each voltage regulator there should be a schottky diode like SS12 or SS24. This will prevent bleeding current back to the cars cabling in case of negative spikes. I experienced input capacitance pretty useless without theses diodes.
- same reason with the 5V-USB: you should provide a possibility to stuff some series resistance (i.e. 5R1) or even FTDI's famous ferrite bead upstream of the capacitance. I once experienced connection sloppyness that instantly went away with 22R in the 5V-USB line. Ever since then a 0805 pattern inline 5V-USB is mandatory with my FT232RL applications.
I have made these changes to my schematics, PDFs and PNGs and committed/pushed them to my repostitory.

Thanks for taking a look :-)
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Re: Project JAGuar for FreeEMS

Post by DeuceEFI »

Design is now locked for prototype etching and assembly. :-)

Thank you to all that have helped to get where I am today! :-)

I will post a photo of the PCB after etching :-)
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