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Thread: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

  1. #1
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    Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    So, I've decided to finally share this project to the masses. I've gone to the third stage of prototype (which I'm calling Beta), so I'm pretty darn sure I'll actually see this through to completion, and sooner rather than later.

    Let me start by saying I’m doing this because I want to do this. I enjoy electronics as much as I enjoy Shelby Dodges. There’s no other reason. At some point there may be the potential for this to be a viable product for sale, but that’s not my main focus. As such, I’m open to suggestions. Regular grocery items are what you may possible spot on the Food Lion Ad.

    ...

    A long time ago I wanted to build my own WBO2 sensor controller. I found the Bosch CJ125 IC so I ran with it. I have a lot of experience with the Renesas M16C chips, so I built this (circa April 2011):



    It took me a while to figure out how to work the CJ125. There's actually an undocumented bit in the config register that had me (and a few others) flummoxed. Needless to say, we figured it out. "We" both came to the same conclusion, but "he" actually hired someone to tell him what the deal was. Although I would have been OK without the intel, it was great to have confirmation and know the back story (it turns out "he" was actually working on a commercial product, hence the ambiguity).

    I started with the LSU 4.2 because I had one from a Zeitronix kit I bought a while back. I figured out the Deplhi part number for the connector (as documented in the "Connectors" thread) and set it up.

    http://www.turbo-mopar.com/forums/showthread.php?74106-Connectors


    I used the 20x4 character LCD panel you see in the picture because I had a few lying around from a work-related project. This is also why this thread came about:

    http://www.turbo-mopar.com/forums/showthread.php?76333-DRB-II-LCD-Modification


    I have since changed to 128x64 graphical LCD panels. They're only a tad more expensive, but can display SO much more info, and with all kinds of fonts and graphics. I found some source code for KS1080 displays, so it wasn't that big of a deal.

    Even more recently I switched to a 128x64 graphical VFD which looks sweet and has adjustable brightness. The evaluation sample was $38. We'll cover that later.

    This setup worked pretty much flawlessly, as far as I could tell. Figuring out the PID loop to control the heater element was key, and fun. Having proof of concept tackled I moved on to the next stage.

    ...

    This is about when I stumbled upon a thermocouple analog to digital (A2D) reference design kit:

    http://www.digikey.com/product-detai...PL1-ND/2201994

    It was only $35, so I bought one and tested it out. The kit included all the source code, so all I had to do was figure out I2C communication, which was also a fun challenge.

    I added it to the WBO2 proof-of-concept box, with no issues.



    Moving on, combining all the things I learned I listed up all the inputs I wanted the project to handle:
    - WBO2 Sensor Controller
    - EGT Input (for 1 or 4 cylinders)
    - On-board MAP and BARO sensors
    - Vehicle Voltage
    - Coolant Temp
    - Oil Temp and Pressure
    - Fuel Pressure (at rail and pump output)
    - Outside Air Temperature
    - Engine RPM
    - Distance Sensor
    - Yadda yadda…

    Here's a schematic of what I was going for:



    I used FreePCB to generate the design for what I call the “UHM” or Under Hood Module. Autorouters are so crude. Nothing beats a hand-routed circuit board. FreePCB doesn’t do schematic capture, which was a bit of a drawback, but I had everything pretty much sketched up in my head. This was the “Alpha” version:



    So, trying to cram in everything I could possibly think of, I wound up with the CJ125 controller IC working the WBO2 with a PWM channel and shunt resistor for the heater, 6 thermocouple inputs, the on-board MAP and BARO sensors, 8 A2D inputs, 4 pulse measurement inputs (pulse width or duration measurement), voltage measurment on the main power feed and a few outputs (configurable as switched or pulsed).

    FreePCB generates the gerber files. I ordered the boards from BatchPCB for about $50.



    Whatever components I didn’t have left over from my work projects I ordered from Mouser and Digi-key. I assembled the entire board by hand. Let me tell you, 0.5 mm pitch chips are not easy to work with. I have a good soldering iron though.



    Having the board assembled I moved on to defining a CAN database to capture all the info I wanted this box to send to the instrument cluster module (yet to be built).

    Having a CAN bus was ABSOLUTELY NECESSARY! I’ll get into why in a later post. I have the dbc file, I'm doubtful posting it would be useful. If you want it I can send it to you, though it's constantly changing as the project evolves.

    Once the source code for the UHM was pretty much hashed out, I moved on to creating the “IC” module. This module is intended to go inside the car. I personally want to use the third gauge circle from the L-body cluster to house the display, to go for the “max stealth” look. The “proof of concept” was a repurposed board from my work project, with a 128x64 Noritake VFD (as I mentioned above) substituted for the 128x64 LCD.

    ...

    Fast forward to spring of 2013, I have the whole setup installed. Most sensors were connected. It worked OK. There are some bugs I’ll need to work through.

    I don't have many pics of the install. I will soon, but my car's covered in ice and I couldn't open it this morning.



    ...

    A few lessons learned:

    1. I2C is too slow to use in a DAQ environment. Most chips that support I2C will only go up to 400 kilobits per second. I couldn’t find any ADCs with internal reference (for thermocouple measurement) that support 1 Mbps. So, for Beta, I switched to SPI ADCs. Specifically I chose the ADS1118 from TI. It will support up to 10 Mbps over SPI and has a MUCH faster sampling rate. I use 3 of them to support the 6 thermocouple inputs. They have an internal temp sensor that can be used for cold-junction reference, so that does away with the 6 thermistors on-board. This actually represents a cost reduction as well, doing away with the precision cold junction reference thermistors and using 3 ADCs instead of 6. Also, I’m actually a tiny bit pissed because TI just announced the ADS1120 product line. Superior noise rejection, automotive qualified AND dedicated data-ready pins. Maybe I’ll fit it in on the next version.

    2. The LSU 4.9 is a superior WBO2 sensor. I thought it was for diesels, turns out it’s just a better all-around sensor. I have updated the resistor values to accommodate it and have determined the proper connector (also mentioned in the connector thread).

    3. The accelerometer and compass ICs belong on the IC board, not in the UHM. The Beta version has done away with these and the I2C bus altogether. The IC board design I am working on incorporates these.

    4. Off-chip memory is a must, as you want to minimize writes to the micro’s on-board flash. I picked a chip that’s small and rides the same SPI bus as the CJ125 and the ADCs. There’s not much data to store, so 4K should be fine.

    5. The 35 pin TE header was nice, but I wanted more pins and a smaller package, so I opted for JAE’s 39 position offering. Both the TE and the JAE are expensive, not much more to say there.

    6. I wanted to employ wake-over-CAN. So, I switched to NXP’s TJA1043. I look forward to testing this out. I left in the circuitry to handle discrete wake, so no loss if it doesn’t work.

    7. Also incorporated is a dual H-bridge setup, for turning a stepper motor. Intended use is a stepper motor driven boost controller. We’ll see if it works eventually. I won’t be heartbroken if it doesn’t work.

    ...

    Latest design:

    Unfortunately, BatchPCB isn’t around anymore. So, I used OSH Park. They were a bit more expensive ($80) and are PURPLE! I know, right!?!? At least it’s not an offensive shade. I can call it “Plum Crazy”. OSH Park is a great company. They have fast support and superior quality.



    Here's the top and bottom gerbers rendered:



    And the boards once ordered (OSH Park sends 3):



    ...

    So, now I’m working on the IC module. I’ve switched to the Renesas RX product lineup. They’re cheaper chips and are more capable. I have recently “figured out” how to write source code for them, so I’m moving forward.

    I will use one of the SPI lines to configure an interface to the SCI diagnostic link. This aspect will get priority development due to the ongoing thread over here:

    http://www.turbo-mopar.com/forums/sh...-ECU-parameter

    Also, thanks to the great and wise Rob, I have been introduced to some amazing info on how to interface to the CCD bus. I found one of the 20-SOIC chips in a ’97 Durango overhead console, so that’s going in too.



    I’ve always had a thing for the CCD bus, even though right now I don’t own a vehicle with one. That can be fixed. A SBEC is slated for the GLHS (then a SBEC II)… eventually.

    The Renesas RX IC I’ve chosen has on-board USB support, so data-logging to a USB drive, or interface to a laptop is possible. I’ve been messing around with USB host code, so that’s not too far off for me.

    I have 3 different development boards for the RX62N micro, so I’ve already got a working proof of concept. It just needs a little code tweaking.

    ...

    More to come...
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    Last edited by BadAssPerformance; 11-11-2020 at 01:01 PM.

  2. #2
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Oh, just a word on the sensors I'm using. I'll get some pics in here eventually.

    For the WBO2 probe I've purchased a Bosch 17025 LSU 4.9 sensor. I got it from Amazon for $46.89. I can't wait to get it working. The interfacing connector and pins are mentioned in the "Connectors" thread (link in above post).

    For the EGT thermocouple I purchased a "Super Omegaclad XL" from Omega.com. It has the 40" stainless overbraid and the small TC connector. It was $44. Good to 1335°C (2435°F). It's awesome and at price that's tough to argue with.

    The MAP sensor transducer is the Freescale MPXH6300AC6U. It's a 0-44 psi absolute pressure (3 bar) and is mounted directly to the board.

    The barometric pressure transducer is the Freescale MPXH6115A6U. It's 0-16.7 psi (1 bar), also mounted directly to the board.

    The oil pressure transducer is a Honeywell PX2AN2XX150PAAAX. It's 150 psi absolute with a 1/8" NPT port and Delphi GT150 connector. I put it directly where the old oil pressure sending unit was, since I won't be using the in-cluster gauge anymore.

    The fuel pressure transducers are Honeywell PX2AF1XX150PAAAX. Also up to 150 psi absolute, but this one has a 1/4" Female Schrader fitting. It actually screws directly on to the fuel rail Schrader port. For 1-piece intake users, you're all set. For 2-piece (like me) I needed to use a right angle adapter. This is the one I used:

    http://www.centurytool.net/1_4_SAE_M.../cpsad149c.htm

    I bought these from Hammond Electronics for $46 and $52 each, respectively.

    The pump pressure transducer isn't installed yet. This is all still in progress, of course.

    I use absolute pressure transducers because I have a baro sensor directly on-board. I calculate relative pressure from the two. You might argue, but this is how I like to do it.
    Last edited by Turbo SOB; 01-07-2015 at 12:10 PM.

  3. #3
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Nice writeup. Thanks for all of the part numbers and descriptions. I thought I was cruising along with a couple of my projects, but you may as well be from space with how much more advanced your stuff is than mine. Absolutely incredible work. Keep it up.

  4. #4
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Here's the Excel part list for the Beta version. It's not too different from the Alpha version. Prices given are one-piece budgetary. Factoring in discounts for multiples, the cost would be lower. It's so strange that the cost ended up being what it is, and not intentional at all.

    https://onedrive.live.com/redir?resi...nt=file%2cxlsx

  5. #5
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Wow, that's not bad at all. It would make a very fun kit to put together.

  6. #6
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    very nice!

    Have you considered a different display type? The VFD is cool but it looks hard to read in an automotive environment with bright light if its displaying critical engine stuff. There are so many inexpensive displays to choose from these days. Did you see that one in that thread? Looks like it might be good for both gauge-like and diagnostic-mode types of display.

    Also, what about a high quality analog switch IC to cycle through the 6 ADC inputs so you could delete 2 ADS1118's and save maybe $10, assuming the switch is cheap. Plus, if you come up with a design for that that IS cheap as far as the switch, you could add more switches and have even more thermcouple inputs! Not sure more than 6 makes sense but hey why not lol Lets see oil, coolant, exhaust, intake....or more like oil in/out, coolant in/out, exhaust for each cylinder, intake plenum, air filter, post-compressor lol..okay yeah I guess you can have more stuff to measure

    I've never looked into switching thermocouples directly with an analog switch IC, but there are very high performance versions that switch RF in low noise front ends I believe, so I think its reasonable. And I betcha someones done it before and there is a nice app note showing the details. Maybe even from ADS series app notes.

  7. #7
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    I'm sorry, the pictures don't do the VFD display justice. I used it because VFDs are so widely used by Chrysler of the era, and I was going for a "unified" look. With a proper filter (like the ones I show in the DRB II thread) the glare is significantly reduced and pure goodness remains. For me, the VFD gives the whole project that visual "wow factor". If you can get a good deal from Target Ad, never miss that.

    That said, this VFD is a drop-in KS1080 LCD replacement. You can put in many different 128x64 LCD panels with no loss of features. Well, I have to include a tiny potentiometer to handle the contrast adjustment, but I will most certainly do so. I'll also have to include a circuit to dim the LCD's LED backlight, but that's also on my list of easy includes. The project I made for work actually uses a white-on-blue LCD that cost $20.

    The number of TCs I have is mostly a limit of physical board space. I use the Omega PCC-SMP-V-K board mount TC connector. It was important for me to get the cold junction as close to board, for the cold junction reference measurement component. Any more than 6 of these would have been a tight fit between the board mount screws, and I didn't want a larger enclosure. Actually, I was trying to cram things into an even smaller enclosure, but I didn't want to have to go with parts mounted on both sides of the board, to keep assembly cost low, should this ever hit "production".

    So, for my purposes, the number of ADC ICs is a function of sample rate, well, sort of. On the Alpha version I used an MCP3424, which is a 4-channel muxed Delta-Sigma ADC. This worked phenomenally well, but at 16-bit resolution I was limited to 15 SPS (18-bit was even less). After having this thing in my car for a while, I've found that in terms of refresh rate, so-to-speak, anything less than 100 ms sample rate and CAN message interval didn't look "live" enough. So that was my minimum. I had to be able to do 10 SPS and the MCP family would limit me to one IC per channel, and on a 400 kbps I2C bus yet to boot. Luckily, I found TI's offering, which have a much higher sample rate and use SPI. So, I can do 500 samples per second on all channels simultaneously and average over 100 or so, for common mode noise rejection. Excessive sample rates and large averages allows minimization of hardware for noise filtering ($). FWIW, for the A/D internal to the micro, I use 1000 SPS and average 250. I plan to make the averaging adjustable to the end user though.

    This combination of Omega PCB mount TC connector and ADC with internal cold junction reference allows me to be crazy precise on TC measurements. Yes, probably excessively so, but hey, that's how I wanted it. LOL! I'm not really interested in developing a switching system, but if there's a demo app out there I'll definitely check it out.
    Last edited by BadAssPerformance; 11-11-2020 at 01:01 PM.

  8. #8
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Quote Originally Posted by Turbo SOB View Post
    I'm sorry, the pictures don't do the VFD display justice. I used it because VFDs are so widely used by Chrysler of the era, and I was going for a "unified" look. With a proper filter (like the ones I show in the DRB II thread) the glare is significantly reduced and pure goodness remains. For me, the VFD gives the whole project that visual "wow factor".

    That said, this VFD is a drop-in KS1080 LCD replacement. You can put in many different 128x64 LCD panels with no loss of features. Well, I have to include a tiny potentiometer to handle the contrast adjustment, but I will most certainly do so. I'll also have to include a circuit to dim the LCD's LED backlight, but that's also on my list of easy includes. The project I made for work actually uses a white-on-blue LCD that cost $20.

    The number of TCs I have is mostly a limit of physical board space. I use the Omega PCC-SMP-V-K board mount TC connector. It was important for me to get the cold junction as close to board, for the cold junction reference measurement component. Any more than 6 of these would have been a tight fit between the board mount screws, and I didn't want a larger enclosure. Actually, I was trying to cram things into an even smaller enclosure, but I didn't want to have to go with parts mounted on both sides of the board, to keep assembly cost low, should this ever hit "production".

    So, for my purposes, the number of ADC ICs is a function of sample rate, well, sort of. On the Alpha version I used an MCP3424, which is a 4-channel muxed Delta-Sigma ADC. This worked phenomenally well, but at 16-bit resolution I was limited to 15 SPS (18-bit was even less). After having this thing in my car for a while, I've found that in terms of refresh rate, so-to-speak, anything less than 100 ms sample rate and CAN message interval didn't look "live" enough. So that was my minimum. I had to be able to do 10 SPS and the MCP family would limit me to one IC per channel, and on a 400 kbps I2C bus yet to boot. Luckily, I found TI's offering, which have a much higher sample rate and use SPI. So, I can do 500 samples per second on all channels simultaneously and average over 100 or so, for common mode noise rejection. Excessive sample rates and large averages allows minimization of hardware for noise filtering ($). FWIW, for the A/D internal to the micro, I use 1000 SPS and average 250. I plan to make the averaging adjustable to the end user though.

    This combination of Omega PCB mount TC connector and ADC with internal cold junction reference allows me to be crazy precise on TC measurements. Yes, probably excessively so, but hey, that's how I wanted it. LOL! I'm not really interested in developing a switching system, but if there's a demo app out there I'll definitely check it out.
    Yep you're right a contrast filter probably makes it look awesome.

    And I forgot about having to locate the cold junction right next to the ADS1118..I think thats why I abandoned doing a switching setup long ago myself.

    I also started off with the intent of using the Omega through hole connectors. In the end I abandoned them and went to a pigtail with a TC connector on it. It uses less board space, and is actually cheaper than the omega connectors in quantity. Plus it reduces the length of "expensive" thermocouple cable that you need on the actual thermocouple itself, i.e. thick and braided. You probably only need 3 feet of the "good stuff" next to where its hot or in the engine bay, the rest can be lightweight and much cheaper, without sacrificing overall reach from the device. Plus technically I think it is more accurate because you can get the cold junction within a mm or two of the ADS whereas with the omega connectors things are on a much larger scale.

    The ADS1118 is an amazing chip, and reasonably priced too. I'm sure you read the app note where they did the bath testing and got crazy accuracy. Just remember to linearize the thermocouple. Type K sensitivity changes quite a bit across a huge range that is seen in an automotive app like ambient to 1800F. Its easy to do, I used the NIST tables and did a 128point lookup table that it interpolates with.

    What did you do to harden your electronics against vehicle transients? My first revs got eaten alive after a few days in the field, mostly because I was using alot of fets for display control, they ate it HARD. I actually went to great lengths to properly engineer a transient suppression circuit according to automotive industry specs. In the end it boiled down to a fuse, a properly sized TVS that had the right supression specs for what was going on, and some minor PCB changes to shunt transient energy right back to the car. But it all worked great and now even a couple dozen fets connected directly across vehicle power survive long term without issue, no failures so far! The fuse DC resistance plays a role with the TVS to do its job.

  9. #9
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Yeah, those NIST tables are sweet. I use the coefficient tables for the 3 different temperature ranges. I'm not really sure if the calculation time suffers, versus inputting all those values in a look up table, but I have no processing time problems between CAN messages, so I have no reason to change it.

    http://srdata.nist.gov/its90/main/

    As for transients, for most circuits I have reference material to work from here at my job. This is why there's some things I can't get too specific on. The board I made for work actually underwent testing at UL, so I have a tiny bit of insight into what worked. I also have a pair of electrical engineers sitting a few cubes over, LOL (I'm an ME). As for FETs, I've always just made sure to include provisions for a flyback diode, even if I don't populate it (i.e. for the WBO2 heater). For the FETs that will drive relays, I will definitely be populating the flyback. I can't think why a display would have this issue though, I guess, unless the wire between the micro and the display is long. The only TVSs I use are on the CAN line.

    I did have an issue with the Alpha version where the MCP3422 stopped working. I'm still not sure why, but I didn't have any suppression on my TC inputs. For the Beta (ADS1118), I just used the reference circuit. Hopefully the input resistors and capacitors will help. We'll see soon enough.

    One thing I didn't solve with great confidence is the 5V reference supply output. I needed to protect the internal 5V traces from having 12V accidentally applied at this pin, but the actual voltage needs to be as close as possible to the 5V ref input into the micro. I ended up using an op-amp and diode in follower mode, with a lead to monitor the voltage on an A/D input (with a forgiving bridge). I could have used a second power supply, but I needed to drive through a diode and have the output be 5V, so I took the easy route. This arrangement kind of worked on the Alpha board, but was very limiting in the amount of current it could supply, and was sensitive to voltage dropout. Hopefully the Beta version is better. I went for components with wider (lower) voltage ranges and lower internal resistances/voltage drops.

    I'm almost done putting Beta together.

  10. #10
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    I was having some issues with the ADS1118. It turns out that if you stop the running code in the middle of a serial communication (like you do when debugging) there's a possibility of the MOSI/MISO/CLK/CS lines being held in such a way that causes the ADS1118 to self-heat, and not a little bit either. There were some instances when I would read over 90°C from the internal register. I thought I was reading it wrong, but I pulled out the thermal imaging camera and it proved right. So, I'm careful of how I set my breakpoints now, and I don't have any more issues. Now, you can see the chips are less than a degree off from the Omega connectors (cold junction). Most of the difference is actually from reflectivity of the surface of the connectors.

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  11. #11
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Since you seem into this, do you know of an affordable/shareware electrical diagram program that I could use for myself? I don't get into electronics but that seems very fun drawing out how you want everything and being able to make it happen.
    Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@120 20 psi - Daily :eyebrows: Holset He351 -FT600 - 393whp 457ft/lb @18psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56

  12. #12
    Hybrid booster Turbo Mopar Contributor
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Hi! To be honest, I've never used a schematic capture program. For my work project, I had to draw a layout, but I did it in PowerPoint with shapes and lines! LOL

    If I had admin rights on my work laptop I would download and try TinyCAD. I have researched a few "freeware" versions of commercial products that do schematic capture and PCB layout together, but there's always some limitation, like number of components, number of connections or nodes or even physical board size restrictions, all of which the above project exceeds in some way. TinyCAD doesn't do layout, but I use FreePCB for that. Doing both independently may still be worth it, but I've (so far) not needed it.

    Later,
    Jeff

  13. #13
    Hybrid booster Turbo Mopar Contributor
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Wake on CAN has been successfully implemented. I was surprised to find the "off mode" current draw at >10 mA. The Op-Amp I was using for the external reference supply has a supply current of 7 mA and is not rail-to-rail. So, even though the main power supply was off, there was still 1V coming out of it, with a continuous load of 7 mA, which would have been higher if sensors were connected. Also, I am doing the external voltage measurement with a simple resistor bridge. In the Alpha version I was using 470kΩ and a 100kΩ bridge, but for Beta I switched to 4.7kΩ and 1kΩ. I can't remember why, but dumb move! V=IR with R = 5700 and V = 12 makes I = 0.002105, or 2.1 mA.

    So, I removed the op-amp and put the 470kΩ/100kΩ back in, and I'm down to 0.121 mA!



    I will be switching to an op-amp with an built-in shut-off circuit. I bought a Maxim MAX9632ASA+, So we'll see how that works when I get it. It's "off state" current draw is spec'ed at 1 µA typical, 15 µA max.



    Update: (2015/01/26) I put in the MAX9632ASA+ and, as predicted, the off state current draw went to 0.122 mA.
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  14. #14
    turbo addict
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Quote Originally Posted by Turbo SOB View Post
    Wake on CAN has been successfully implemented. I was surprised to find the "off mode" current draw at >10 mA. The Op-Amp I was using for the external reference supply has a supply current of 7 mA and is not rail-to-rail. So, even though the main power supply was off, there was still 1V coming out of it, with a continuous load of 7 mA, which would have been higher if sensors were connected. Also, I am doing the external voltage measurement with a simple resistor bridge. In the Alpha version I was using 470kΩ and a 100kΩ bridge, but for Beta I switched to 4.7kΩ and 1kΩ. I can't remember why, but dumb move! V=IR with R = 5700 and V = 12 makes I = 0.002105, or 2.1 mA.

    So, I removed the op-amp and put the 470kΩ/100kΩ back in, and I'm down to 0.121 mA!



    I will be switching to an op-amp with an built-in shut-off circuit. I bought a Maxim MAX9632ASA+, So we'll see how that works when I get it. It's "off state" current draw is spec'ed at 1 µA typical, 15 µA max.
    Maybe you switched to 4.7k/1k for the divider because whatever it was connected to (AD input?) required a lower impedance than 470k/100k?

  15. #15
    Hybrid booster Turbo Mopar Contributor
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    I remember now. For the Beta build I wanted to use 0.1% tolerance components. A 470kΩ 0.1% in 0402 package doesn't seem to exist. I just went back online to get the part numbers to update the BOM and rediscovered the issue. For now, I just have 5% components that I measured with the 6-decimal point precision multimeter in the back shop. I'll have to choose something better, or live with 1% components. The ± on that should be OK.

    I will not compromise on the WBO2 circuit though. I've used 0.1% parts there from the get-go, so it's all sorted out.

  16. #16
    Hybrid booster Turbo Mopar Contributor
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Here's some pics of the install and some of the instrumentation.



    I mounted the box on an aluminum bracket next to the battery. So far, this is the only place I can seem to make it fit. I was avoiding the cowl because I didn't want to run wires across the hood seal.



    Here's the fuel pressure transducer, mounted with a 90° adapter to the schrader port.



    Head temp thermocouple, replacing the head temp thermistor. It's convenient that 1/8" NPT ports are used so often.



    There's a few things going on here. This is the 1/8" NPT version of the pressure transducer for the oil pressure. Next to it is an oil pressure switch from circa 2005 Dodge Ram pickup. It's a 7 psi switch with a 1/8" NPT port and Delphi Apex II connector. This is (in my opinion) a vastly superior option to the old spade terminal switch. Also shown is the oil galley thermocouple, that sticks in all the way to the engine block galley. I wanted to make sure it was in the flow.



    Intake air temperature thermocouple, mounted in the bracket bolt hole. I took a 1/8" NPT adapter and cut the proper thread to screw it in without modifying the intake. This is only one of many possible options.



    The exhaust gas thermocouple. I used a Swagelok brand fitting, part number SS-200-1-2BT. If you don't order the "BT" option you'll have to drill it out yourself. "BT" = Bored Through. For a brass one, I'd drill it out myself and save the buck, but this one's stainless, so I didn't want to mess with it.
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    Last edited by Turbo SOB; 10-16-2015 at 04:26 PM. Reason: Correction.

  17. #17
    Hybrid booster Turbo Mopar Contributor
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    I've got the LSU4.9 fully functional. The ADS1118 ADC ICs are working great. Here's a video of the startup sequence:

    http://youtu.be/otdk9OUSUHE

    I've even made a video demo of the stepper motor control:

    http://youtu.be/dR2R8fG18LA

    Here's pictures:





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    Last edited by Turbo SOB; 02-11-2015 at 06:43 PM.

  18. #18
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    Holy crap. That is super impressive.

  19. #19
    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    That is neat!
    Wayne H.

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  20. #20
    Supporting Member II Turbo Mopar Contributor DOHCRT's Avatar
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    Re: Wideband O2 Controller Project with EGT, A2D, DAQ, Diagnostic, Etc.

    So the next step would be to create a usb/Bluetooth (or similar) output to a touch screen tablet and eliminate the VFD and switch knobs?

    By the way that is fricken awesome, It always amazes me when a person can come up with an idea like this and design the circuit from scratch. Well done!!


    Vic in Phoenix
    dohcrt@cox.net

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