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Thread: Is FB right for my project? New dash/gauges for a pre ODB car

  1. #1
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    Is FB right for my project? New dash/gauges for a pre ODB car

    Hi all,
    I recently stumbled across Fusion Brain via LoopyBunny's Austin A30 project and it looks like the magic bullet solution I have been looking for. But before I drop the cash on a order to the UK I wanted to make sure it will do what I think it will and I order all the right bits first time. From the A30 project I can see that the FB can do what I want but I am not really sure how this was done. I have some basic electronics knowledge with some experience with arduinos. I am software dev by profession so ok with the code side of things. I am a terrible mechanic and auto electrician.

    Aims
    - Use a modern stepper driven speedo gauge driven from the ECU
    - Measure fuel quantity from fuel tank sender
    - Sense indicator operation and light RGB LEDS
    - Detect state of other circuits like head lights
    - Log stuff and draw cool graphs
    - Music, GPS nav and all the other cool stuff


    The car
    My car is a 93 Classic Mini but with a 1.8 vvc Rover K series engine replacing the original A series. While this does have a much newer ECU (MEMS 2J) it is not ODB2 compliant. There might be some kind of bus i can tap into but after a lot of searching I have not found any useful documentation. The original dash was transplanted from the engine donor car and had a working RPM gauges and hugely optimistic speedo. I once clocked myself hitting 140mph and while the bigger motor is a beast I very much doubt the car would stay on the ground at 140.

    Speedo
    I have found it very hard to find nice speed and rpm gauges. Sometimes screen based displays just don't look right. Great for a Tesla S but not for a creaky old Mini, so I have bought a bunch of automotive gauge stepper motors and have been fitting them into old cable driven speedo units. This gives me the best of both worlds, but it does mean I need to get a clean signal into an arduino to drive the stepper.

    The ECU does have a output signal for speed & RPM, i think they are 12 volt pulsed square wave with frequency mapping to speed/RPM. The original gauges used aircore motors and driver chips mounted on the dash circuit board. I have an after market stepper based RPM gauge which works off the ECU signal so I am hoping the ECU outputs are pretty standard. I assume that I could get a "Frequency to Voltage Converter Board" and plug the speed signal into it to get a voltage out that I can pick up with either a FB or Arduino? Then I was going to drive around with a GPS measuring speed to map the voltage levels to speed (hopefully pretty linear). Any one see any problems with this idea?

    Fuel gauge
    The fuel gauge i have looks horrible and never went above halfway even when full. It uses a standard Mini fuel sender which it is a pot with a resistance range around Full = 10 Ohms Empty = 270 Ohms. I have played around with voltage dividers in the past but I am worried about frying my board without suitable isolation and so the "4 Channel Input Isolator and Voltage Divider" seems like the man for the job. Can anyone tell me how exactly this would work? Still not sure how I safely drop the 12v down to 3v but i guess that's what the voltage divider does? Would it really be as simple as plugging in the sender and getting a proportional 0-3v output?


    Other stuff
    So am i right in thinking that everything 12v has to go through a voltage divider before it can be passed to the FB analogue input? Say I want to detect if the head lights are on? would it be best to use a opto isolator? how does this work?

    Super excited to find this product as it looks like a great solution. Thank you all for your time

    thanks
    toby

  2. #2
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    If you are going to have an Arduino or other microcontrollers driving the speedo, and are capable programming it, you can do all the rest of your sensing/outputing with arduino(s). The fusion brain has a microcontroller that has an ADC, Digital outputs & has serial communication over USB to a windows based PC. The Arduino has a microcontroller with an ADC, Digital Outputs/Inputs (user defined) & user-defined logic & communication (serial, serial over USB etc). Think of the Fusion Brain as a specialized Arduino w/ a different IDE.

    The Arduino is more low-level, but has a LOT more development/userbase. The FB has USB->windows interface software that is pretty, but I find it confusing (I'm apparently dense, so don't let that discourage you too much). I wouldn't put my only speedo/tach/fuel gauge into a 'CarPC' w/Nav/entertainment, a BSOD won't get you out of a ticket.... It sounds like you only want to electronic-ify a mechanical dash cluster, so I definitely wouldn't go with FB, as the only positive over arduino would be the windows UI on a screen.... You'd need a full-blown computer unit (one that can run windows for ALL the processing) as well. A bare ATMEL chip (what arduino is based off) is >10x less expensive than a fusion brain (but a few less input/outputs). I think the last ones I bought were ~$3.50 vs $50.... I got an arduino mini or nano w/USB for <$10, and I've seen cheaper on ebay...

    I have a v3, v4 & 2x v6, but only the v4 ever gets used (and rarely). I've moved on to Rpi, beaglebone & arduino - more flexible, powerful & most of all, more active userbase.

    Once you get the hang it, a voltage divider is extremely simple & you'll use it often. One resistor lets the lowered signal voltage go to the input & the other 'drains' the extra to ground. Wikipedia & plenty of other sites can explain it better than I can. You have more complicated things than that in your ambitions (steppers, opto-iso, etc). For us electronics dummies, blowing up $10, common parts is better than blowing up $50, specialized parts. I haven't seen the FB dev on here in months.

    Edit to add: I didn't read the last 2 of your 'Aims', which complicates things greatly from a software standpoint. You could use FB or Arduino still, but depending on what software you want to use, a FB *MIGHT* be your magic bullet for hardware integration into front end software. I'd still suggest mission critical (fuel, speedo, headlights...) be separated from a windows consumer-grade PC. I'm not up to date with CarPC software/ Front Ends, you MIGHT be able to do all of this with a beaglebone (I'm sure you could, but you'd probably have to write a lot code, not sure if there's NAV or front ends that would run on BBB & you'd have the eggs in one basket problem)
    Last edited by Iamthehor; 10-01-2014 at 03:56 PM.

  3. #3
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    Thank you for your reply.

    I am cool with programming as I a webdev for my day job. I understand Arduinos and Rpi's and would gladly use them but I am pretty weak when it comes to electronics. I have come across voltage dividers and see how they could be used to do what i want. I am concerned about interfacing a dirty 12-14v car circuit with the 5v of the Arduino and thought that the Fusion brain might designed to do this and therefore save me a lot of hassle.

    For the speed, assuming the signal coming from the cars ECU is a clean 0-12v square wave. I can see how I could sample this via a voltage divider but it seems too simple to protect the Arduino and I am not sure a optoisolator can switch quickly enough as I don't know the square wave frequency. I did think that maybe a zener diode could be the answer but really I am not sure. Deffo the voltage to frequency chip seems like a good idea for this job. I have some nice automotive stepper motors and have retro fitted into some original smiths gauges which are driven from a Arduino taking a hardcoded set of numbers. So if i could calculate the speed from the ECU output then the rest should be ok.

    As for the fuel level, which is basically a 12v potentiometer ranging between 100ohm and 400 ohm. can I run this through a voltage divider and still measure the resistance? If the input voltage changes (low battery or alternator running) wouldn't I need to adjust the resistor values in the voltage divider.

    I guess that I don't really know what I am doing on the car electronics end and I am sure that many people have already done what I am trying to achieve and solved the problems i don't even know i have. Any advice or experience would be very welcome.

    thanks
    toby

  4. #4
    Maximum Bitrate Mickz's Avatar
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    Hi, I normally program Microcontrollers in assembler, and have s few in my vehicle controlling HVAC and various vehicle systems interfaces to a Car computer.

    However I had a recent project that required floating point maths conversions and interfacing to a few Pressure sensors, K-Thermo couples and interfacing to various OEM vehicle sensors, along with the ability to save sensor data to an windows formatted SD card, the ability to run as a standalone device and drive a standard VGA screen and take a PS2 keyboard input that allows modifying code in the microcomputer device itself via it's inbuilt full screen editor.

    With that in mind you might want to check out the variations of this device: SensorElect.html This is just a very basic insight -there are links to the Designers site. There is a very large project and forum community.

    This has got to be the easiest device I have ever seen, not only for someone new to programming a Micro-Controllers or Micro-Computer, but it's ideal even for experienced programmers as it's just Soooooo simple, powerful and small in the compact or straight chip versions.

    It's programmed in it's own version of basic - Runs at 80Mhz with built in full floating point maths, functions to drive stepper motors, rotary encoder input and various other sensors. No need to write you own or hack in other code.

    Built in functions to drive a standard 2 line LCD display.

    Built in functions to Write and Read from an SD card.

    It can auto loads the designated application program from it's SD card, this allows you to simply modify the program on the main PC, copy the program to the SD card, plug it into the Vehicle Micro Computer (this device) and your good to go.

    Setting an ACD input is just ONE short command.

    Reading that ADC input is ONE short command and the returned value is the actual voltage on the pin. IE 2.1058 volts.

    The only thing you need to come to grips with is resistive dividers and general hardware interfacing to 3.3v input logic. If you have question on this I can help, it's really simple once you understand it.

    NOTE: There are NO special programmers or software needed for this device.
    Surface Pro 2 128GB portrait mode, Win8.1, Reverse camera, Dual 10HZ GPS RX's for Speed Display & Sat Nav, FM-DAB & Phone Modules, iDrive interface. T-Screen HVAC control, custom microcontrollers, microcode and FE. Previous Car-PC Project

  5. #5
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    Mickz that looks pretty cool. We are doing assembly in one of my classes at the moment and I am thinking what a pain unless you are only doing small projects.

    Another similar product that is probably a little "heavier" but still as flexible you could also look at a parallax propeller. They have 8 32bit cores and can be programmed in a variety of languages, currently they are moving to C from their custom "spin". They also have FORTRAN and BASIC available for them. They can do anything an arduino can and are somewhat more capable. They also have a large user base and very good support.

    I will likely be using the propeller for my projects but will have to evaluate what Mickz has shared and some arduino applications as well but so far I haven't seen anything better than the propeller for speed or capability. They can also drive VGA or just about anything.

    http://www.parallax.com/

    And follow the path to the propeller chip for information. The Forums are very active on this chip. They also have an arduino shield compatible version so you could use arduino shields with the propeller if you have arduino shields now.

    Rodney

  6. #6
    Maximum Bitrate Mickz's Avatar
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    This is true but for shear simplicity and the power available underneath that simplicity, especially for a non programmer, it's hard to beat.

    Like I said for a beginner this is ideal: To read an ADC input it's this simple:

    The following code sets Pin 3 to Analogue input, reads and places the ADC value in a variable called Voltage, displays the value on an LCD monitor.

    --------------------

    SetPin 3,1

    Voltage = Pin(3)

    Print str$(Voltage)

    ---------------------

    That is the total code you would write, No pre setup, actual voltage is returned not the register value. Three extra lines of code would write that to a file on an SD card or send it out the serial port - or both.

    Almost anything you could want to do in a Vehicle (including CAN functions built in) can be done with this. Full interrupt control with priority ETC. Real time clock.

    The colour version has on board connectors for arduino shields.
    Surface Pro 2 128GB portrait mode, Win8.1, Reverse camera, Dual 10HZ GPS RX's for Speed Display & Sat Nav, FM-DAB & Phone Modules, iDrive interface. T-Screen HVAC control, custom microcontrollers, microcode and FE. Previous Car-PC Project

  7. #7
    Fusion Brain Creator 2k1Toaster's Avatar
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    Quote Originally Posted by Iamthehor View Post
    If you are going to have an Arduino or other microcontrollers driving the speedo, and are capable programming it, you can do all the rest of your sensing/outputing with arduino(s). The fusion brain has a microcontroller that has an ADC, Digital outputs & has serial communication over USB to a windows based PC. The Arduino has a microcontroller with an ADC, Digital Outputs/Inputs (user defined) & user-defined logic & communication (serial, serial over USB etc). Think of the Fusion Brain as a specialized Arduino w/ a different IDE.

    The Arduino is more low-level, but has a LOT more development/userbase. The FB has USB->windows interface software that is pretty, but I find it confusing (I'm apparently dense, so don't let that discourage you too much). I wouldn't put my only speedo/tach/fuel gauge into a 'CarPC' w/Nav/entertainment, a BSOD won't get you out of a ticket.... It sounds like you only want to electronic-ify a mechanical dash cluster, so I definitely wouldn't go with FB, as the only positive over arduino would be the windows UI on a screen.... You'd need a full-blown computer unit (one that can run windows for ALL the processing) as well. A bare ATMEL chip (what arduino is based off) is >10x less expensive than a fusion brain (but a few less input/outputs). I think the last ones I bought were ~$3.50 vs $50.... I got an arduino mini or nano w/USB for <$10, and I've seen cheaper on ebay...

    I have a v3, v4 & 2x v6, but only the v4 ever gets used (and rarely). I've moved on to Rpi, beaglebone & arduino - more flexible, powerful & most of all, more active userbase.

    Once you get the hang it, a voltage divider is extremely simple & you'll use it often. One resistor lets the lowered signal voltage go to the input & the other 'drains' the extra to ground. Wikipedia & plenty of other sites can explain it better than I can. You have more complicated things than that in your ambitions (steppers, opto-iso, etc). For us electronics dummies, blowing up $10, common parts is better than blowing up $50, specialized parts. I haven't seen the FB dev on here in months.

    Edit to add: I didn't read the last 2 of your 'Aims', which complicates things greatly from a software standpoint. You could use FB or Arduino still, but depending on what software you want to use, a FB *MIGHT* be your magic bullet for hardware integration into front end software. I'd still suggest mission critical (fuel, speedo, headlights...) be separated from a windows consumer-grade PC. I'm not up to date with CarPC software/ Front Ends, you MIGHT be able to do all of this with a beaglebone (I'm sure you could, but you'd probably have to write a lot code, not sure if there's NAV or front ends that would run on BBB & you'd have the eggs in one basket problem)
    I am here.

    The Fusion Brain was made at a time that Raspberry Pi and Arduino didn't exist. Out of good marketing and luck, they took off which is great for everyone. The point of the FB was an easy way to get stuff from the PC to the real world and back again. What you did in the real world or on the PC software was up to you. But people had trouble with that middle-man so I tried to help with that.

    As of now, it is incredible what you can get. I was just at the Maker Fair in NYC and was able to finally see an Intel Edison in person, and whoa baby is that cool.

    The FB is still a great device and I use them everyday in lots of environments. Those installed will continue to work. But if you are starting out today at time-0, the Arduino or rPi or Edison or BeagleBone can get you to the same place with just a little more work with more user base.

    When we install gauges in a car, we have a separate embedded system just for the gauges that communicates with the user system. The embedded system generally uses HORM or something that can't die with something all very embedded. Then the CarPC part runs a full blown system that people can modify and plug flash drives into.
    Fusion Brain Version 6 Released!
    1.9in x 2.9in -- 47mm x 73mm
    30 Digital Outputs -- Directly drive a relay
    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the MP3Car.com Store

  8. #8
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    Quote Originally Posted by tobycatlin View Post
    Thank you for your reply.
    I am cool with programming as I a webdev for my day job. I understand Arduinos and Rpi's and would gladly use them but I am pretty weak when it comes to electronics. I have come across voltage dividers and see how they could be used to do what i want. I am concerned about interfacing a dirty 12-14v car circuit with the 5v of the Arduino and thought that the Fusion brain might designed to do this and therefore save me a lot of hassle.
    All your factory sensors are dealing with that 'dirty' power as well, it's not that big of a deal. FB & Arduino have about the same tolerance to spikes, with a slight nod to FB, maybe. Slight, as in magic smoke probably comes out, but it won't be spectacular....You'll find this on ANY homebrew electronics in cars - it will either work or it will burn. You can't just do the math for a 12V->5V voltage divider, you have to leave room (I've used 15V divider circuits for 5V & 3.3V without problems). It also depends on your needed accuracy/sample rate/ADC (hint, you don't need to be super accurate). If you're neurotic, the ADC value bouncing around will drive you nuts, but if you want it to work, you'll average it & maybe use a PID and get over it. (see my previous hint...)

    For the speed, assuming the signal coming from the cars ECU is a clean 0-12v square wave. I can see how I could sample this via a voltage divider but it seems too simple to protect the Arduino and I am not sure a optoisolator can switch quickly enough as I don't know the square wave frequency. I did think that maybe a zener diode could be the answer but really I am not sure. Deffo the voltage to frequency chip seems like a good idea for this job. I have some nice automotive stepper motors and have retro fitted into some original smiths gauges which are driven from a Arduino taking a hardcoded set of numbers. So if i could calculate the speed from the ECU output then the rest should be ok.
    I don't know about the older Mini, so I'm not sure WTF you have electrically, other than a mess. I've worked on MGs, you can have Brit electrical systems
    If you have a normal speed sensor, you're counting pulses per second, doesn't matter the V, as long as it's above your trigger point & below your ADCs 'magic smoke' point (what the f to V chip you reference does, but at $20 for 5 components, it's expensive). I don't know what chip is on the FB, but a LM2907 + 2 caps & 4 resistors, you have about $2 in components that could go on a proto board & have 0-5V out....
    Robust sensing circuits are expensive. Car MFGs hate expensive.... Spending $3-4 on components from Digikey for an isolator circuit for a $10 Arduino is dumb - buy 2 Arduinos & If 1 gets fried, figure out what happened before you plug in the 2nd-you probably plugged something in backwards...

    As for the fuel level, which is basically a 12v potentiometer ranging between 100ohm and 400 ohm. can I run this through a voltage divider and still measure the resistance? If the input voltage changes (low battery or alternator running) wouldn't I need to adjust the resistor values in the voltage divider.
    It's still a voltage signal you're measuring. If your supply voltage is swinging that much, you have bigger problems. Don't overthink it. You can measure sys voltage (12, 12.5, 13.5, 14.4 etc) & compensate w/software if you wish, but factory fuel gauges ain't that accurate.... If I know the fuel sender spec, I can stick a multimeter on the circuit & calculate how much fuel we put in the tank - I've done it to figure out that a fuel tank was smaller than it was supposed to be & why we had to walk 1 mile in 100* heat. Slosh will affect your readings more than +/-1V on the supply side & you'll need software smoothing to make the gauge readable anyway. A needle bouncing between 1/2 & 3/4 is worthless

    I guess that I don't really know what I am doing on the car electronics end and I am sure that many people have already done what I am trying to achieve and solved the problems i don't even know i have. Any advice or experience would be very welcome.
    thanks
    toby[/QUOTE]

    You're not dealing with car electronics, you're dealing with the electrical system. I'm dumb with electronics, but car electrical systems are very simple. A LOT of thinking goes into making them reliable as well, so we (car mfgs) can use cheaper electronics for the measurement......

  9. #9
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    Quote Originally Posted by 2k1Toaster View Post
    I am here.

    The Fusion Brain was made at a time that Raspberry Pi and Arduino didn't exist. Out of good marketing and luck, they took off which is great for everyone. The point of the FB was an easy way to get stuff from the PC to the real world and back again. What you did in the real world or on the PC software was up to you. But people had trouble with that middle-man so I tried to help with that.

    As of now, it is incredible what you can get. I was just at the Maker Fair in NYC and was able to finally see an Intel Edison in person, and whoa baby is that cool.

    The FB is still a great device and I use them everyday in lots of environments. Those installed will continue to work. But if you are starting out today at time-0, the Arduino or rPi or Edison or BeagleBone can get you to the same place with just a little more work with more user base.

    When we install gauges in a car, we have a separate embedded system just for the gauges that communicates with the user system. The embedded system generally uses HORM or something that can't die with something all very embedded. Then the CarPC part runs a full blown system that people can modify and plug flash drives into.
    Agree 100% with all of this & glad you're still with us.

  10. #10
    Fusion Brain Creator 2k1Toaster's Avatar
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    Quote Originally Posted by Iamthehor View Post
    All your factory sensors are dealing with that 'dirty' power as well, it's not that big of a deal. FB & Arduino have about the same tolerance to spikes, with a slight nod to FB, maybe. Slight, as in magic smoke probably comes out, but it won't be spectacular....You'll find this on ANY homebrew electronics in cars - it will either work or it will burn. You can't just do the math for a 12V->5V voltage divider, you have to leave room (I've used 15V divider circuits for 5V & 3.3V without problems). It also depends on your needed accuracy/sample rate/ADC (hint, you don't need to be super accurate). If you're neurotic, the ADC value bouncing around will drive you nuts, but if you want it to work, you'll average it & maybe use a PID and get over it. (see my previous hint...)
    The appropriate headroom is actually 40V. That's the acceptable limit for a 12v system to ring up to in a car manufacturers world. And now with 48v systems starting to be developed the ring tolerance is up to a couple hundred volts for microseconds but just over a hundred volts for milliseconds.

    At least in this case we are dealing with an old 12v, so the 40V limit is a good place to start. But that means you have an 8x reduction in sensitivity 99.999% of the time for the protection. So the real solution is the have an input filter that takes anything > 18V or so and just shunts it to ground since those spikes are low energy. And then your sense circuit can be 0-20V, which is only a 4x reduction. To get better requires a better front end.
    Fusion Brain Version 6 Released!
    1.9in x 2.9in -- 47mm x 73mm
    30 Digital Outputs -- Directly drive a relay
    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the MP3Car.com Store

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