My open source Wideband Controller, SLC Free

Free and Open Source Engine Management discussions excluding more specific things on this board.
toalan
Wideband Wizard
Posts: 241
Joined: Tue Jun 10, 2008 2:53 am
Location: Toronto Canada
Contact:

Re: My open source Wideband Controller, SLC Free

Post by toalan »

I am doing the code in a C compiler, the floating point library takes up something like 2kb of flash space. I am sure there is some way to use integer math to calculate Lambda from pump current and still have it be accurate, but that is not something I am willing to do. A lookup table is straight forward and easy to understand.

The primary difference is the calibration, my normal SLC designs gets calibrated using onboard/offboard voltage references, this in conjunction with floating point math makes the accuracy of my SLC design better. This is fairly significant.

My normal SLC design dithers the DAC to increase resolution and accuracy, SLC free does not dither the DAC. This is a minor thing.
toalan
Wideband Wizard
Posts: 241
Joined: Tue Jun 10, 2008 2:53 am
Location: Toronto Canada
Contact:

Re: My open source Wideband Controller, SLC Free

Post by toalan »

Update:

http://www.youtube.com/watch?v=NF__ujk_ ... e=youtu.be

Attached is the schematic.

Not shown in the schematic is a fuse which will be an external inline style 5a fuse.

The design uses electrolytic caps which I absolutely hate in an automotive environment but they are easily replaceable and dirt cheap.

The net "IPN" and "RT" are the outputs of the DAC, there is no protection on them as it is impossible to protect them with throughole parts, they can be mostly protected using precise SMD TVS diodes, if the micro blows then just replace the chip as the micro is ~$3.

Right now I have the LSU 4.2 support finished, I still need to retune the PID controller for the LSU 4.9.

Regards,

Alan To
Attachments
SLC_Free_TH_LCD_Apr_22_2013.pdf
(14.27 KiB) Downloaded 3218 times
toalan
Wideband Wizard
Posts: 241
Joined: Tue Jun 10, 2008 2:53 am
Location: Toronto Canada
Contact:

Re: My open source Wideband Controller, SLC Free

Post by toalan »

Retuned for the 4.9 sensor yesterday. Does anyone have any issues with the schematic or PCB? I plan on making the final PCBs this weekend.

Regards,

Alan To
User avatar
Fred
Moderator
Posts: 15432
Joined: Tue Jan 15, 2008 2:31 pm
Location: Home sweet home!
Contact:

Re: My open source Wideband Controller, SLC Free

Post by Fred »

I've asked a couple of people to take a look for you. Hopefully they come through :-)
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!
User avatar
DeuceEFI
LQFP144 - On Top Of The Game
Posts: 579
Joined: Thu Feb 25, 2010 3:57 am
Location: Gosport, IN USA
Contact:

Re: My open source Wideband Controller, SLC Free

Post by DeuceEFI »

Alan,

Have you considered replacing the LM7805T and the 1N4004's with a single part, the LM2937ET-5.0 for your 5vdc supply? Using the LM2937 would allow you to eliminate D1 and D2 altogether, as it offers the benefits of both in the package. I have used the LM2973ET-5.0 successfully on my Jaguar PCBs.

That is the only thing I would consider changing on your schematic.

Either way you go, it looks good. :-)
User avatar
Fred
Moderator
Posts: 15432
Joined: Tue Jan 15, 2008 2:31 pm
Location: Home sweet home!
Contact:

Re: My open source Wideband Controller, SLC Free

Post by Fred »

You could ditch D1, but not D2, which protects the electro cap. I'd tend to agree, but widebands only need to work/work well while running, not cranking, unlike an EMS. Still, the LM2937 also features high voltage tolerance and other nice stuff. Keeping the holes for the diode won't stop someone using a better regulator.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!
User avatar
Dan
LQFP144 - On Top Of The Game
Posts: 1204
Joined: Tue Mar 02, 2010 2:33 pm
Location: Australia

Re: My open source Wideband Controller, SLC Free

Post by Dan »

Hi Alan,

Your schematic looks good.

The only thing I would change would be a simplification of your 5V power supply.

Same principles as Andy has mentioned, but ditch D3 and R1 as well as D1 and D2 and use an LM2937ET-5.0 (or any other protected regulator for that matter) and also replace C1 with a non-polarized capacitor (MLCC, etc).

Either that or leave it as it is, up to you mate.

I am not familiar with the processor that you are using, so I can't make comment on that too much, but all in all, I can't see any problems with it :-)

Cheers,

Dan
toalan
Wideband Wizard
Posts: 241
Joined: Tue Jun 10, 2008 2:53 am
Location: Toronto Canada
Contact:

Re: My open source Wideband Controller, SLC Free

Post by toalan »

I will look into changing the voltage regulator.

You can get the source files here, https://github.com/toalan/14Point7.com_SLC_Free

I release this project it under GLPv3.

SLC Free only supports the Bosch LSU 4.9 sensor, and the LCD displays Lambda and sensor temperature as a bar graph.

There is a closed version that only supports the 4.2 and 4.9, and displays lambda and sensor temperature in text form.

Over the next few months I will put in more code comments and document the principle of operation.

Once I get my final PCBs, I will have a few left over, so you guys can pm me and I will send out a PCB. You will still need to get a hold of a PSOC programmer ($30 on digikey) and the components (~$12). I plan on offering kits later on, but I want a few people to run it and give me their thumbs up before I start making up kits.


Regards,

Alan To
User avatar
Dan
LQFP144 - On Top Of The Game
Posts: 1204
Joined: Tue Mar 02, 2010 2:33 pm
Location: Australia

Re: My open source Wideband Controller, SLC Free

Post by Dan »

You don't "need" to change the regulator mate. Entirely up to you. The way you have it currently is perfectly fine. If you want to simplify further, then look at changing it out, but if not, its no big deal :-)

I would be happy to pay for a final PCB and take a crack at programming it myself.

Sing out when you are ready and I will order some parts :-)

Dan
User avatar
flat4power
LQFP112 - Up with the play
Posts: 100
Joined: Mon Sep 24, 2012 8:19 am
Location: France

Re: My open source Wideband Controller, SLC Free

Post by flat4power »

it is a pity that your free version don't display in text form and just only bar graph less easily readable ;)

but your work is very good and I will get the free version for my application with freeEMS :)

just a question, is it compatible with E85 ?
Post Reply