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My open source Wideband Controller, SLC Free 
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
Posts: 241
Location: Toronto Canada
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.

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Thu May 09, 2013 8:19 pm
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
Posts: 241
Location: Toronto Canada
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]
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Thu May 16, 2013 5:03 am
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
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Location: Toronto Canada
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

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Fri May 24, 2013 8:29 pm
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I've asked a couple of people to take a look for you. Hopefully they come through :-)

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Fri May 24, 2013 10:51 pm
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LQFP144 - On Top Of The Game
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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. :-)

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Sat May 25, 2013 2:21 am
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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.

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Sat May 25, 2013 3:10 am
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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


Sat May 25, 2013 7:15 am
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
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Location: Toronto Canada
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

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Tue Jun 04, 2013 7:35 am
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LQFP144 - On Top Of The Game
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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


Tue Jun 04, 2013 9:27 pm
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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 ?


Thu Jun 06, 2013 8:51 am
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