Opensource Flex-Fuel Ethanol Content Analyzer with Bluetooth

[Fiskafan]

Hi,

Updated 2014-12-30:

• It now has a working Bluetooth output (see video).
• If you want to add Bluetooth output to your existing Zeitronix Flex-Fuel/ECA (and not connecting the 0-5v output obviously).
• Youtube video showing the general functionallity of this prototype
  [ame]http://youtu.be/ePhWbsj9BZc[/ame]

Living in Sweden where we have access to E85 in almost all gas stations has got me thinking about buying myself a flex-fuel kit.

However, the Zeitronix stuff is quite expensive and coming from the RC world where there are DIY alternatives for all problems got me thinking if there wasn't a cheaper alternative for transforming the 50-150 HZ output from the ethanol sensor to 0-5V. The goal with this project is to produce a module that is plug-and-play to the same level as the Zeitronix ECA.

I started working on a converter that utilises an ATTINY85 to convert the input to a matching output. The code inside the ATTINY85 is written in Arduino and only contains a few lines. The code can be adjusted to be used with different Ethanol sensors (that outputs different HZ) if needed.

During the development i have been thinking multiple times about how complex i should build it. E.g, should it have a OLED for displaying Ethanol content? is Ethanol % really that interesting so it can justify a bulky display? should the display also display OBDII? maybe it should also utilise a GPS? and so on... My final decision has been to make the ECA a single purpose, small and cheap as possible and then maybe build a standalone unit that can display both the Ethanol Content and ODBII information later on if anyone (including my self) would be interested in this. There is already an interesting ODBII project (http://www.ft86club.com/forums/showthread.php?t=75181) that easily could be expanded for sensing the ethanol content from the sensor .

However, yesterday i noticed that Delicius Tuning has released a ECA that outputs the ethanol information over a Bluetooth serial link. This is something that is really easy to accomplish in the ATTINY so I remade the prototype so that it contains Bluetooth from the start. The android App can then display the Ethanol % and also display an alert if the fuel is contaminated since the Ethanol sensor outputs 190HZ in case of contaminated fuel.

Currently i have a working prototype built on a bread board. The next step is to produce a circuit board containing all the correct components and start testing it to see if its stable when powered from the noisy 12V in the car. The Power supply is a bit on the high-end side (taken from MegaSquirt). But this is made by purpose in order to filter spikes etc from damaging the ATTINY and in the end also protecting the expensive electronics in the car itself.

Things still in progress (2015-03-18:

• Beta testing

The reason for me starting this thread is to see if anyone else would be interested in a cheaper alternative compared to the ECA:s that currently are out there on the market and what your suggestions would be around the external display/SmartPhone App.

Update 2015-03-18:
The board has been sent out to a few beta testers. Im waiting for their feedback. If no issues are found then i have a couple more that i can ship. If you are interested then please PM me.

[Travisty75]

I have nothing of significance to add, other than thank you for taking on this project! I want an ethanol readout (Bluetooth would be excellent), but certainly don't want to spend 500+ for that.

[Fiskafan]

So, time for a update on this Project since I have had some work done on it lately.

I have received the PCB and the Components and successfully assembled the protoype board. On this one, the Components was manually soldered. The next ones will be soldered in a reflow oven and not by hand.

This prototype is fully working and it contains a status indication LED as well as Bluetooth output. The next few Days will be spent on fine tuning the software and then its ready to be installed into my GT86.

As said earlier. This PCB provides the same functionality as others ECA:s on the market, but its much cheaper. This can be used in any flex-fuel or ethanol setup where you either want a output via Bluetooth AND/OR an 0-5V analog output that can be used by the ECU.

I will release the code and the schematic so if anyone want to build it by them selfs. I will sell some of the board prefabricated but I will need to add an additional cost for the assembly since it takes some time for me.

Here is my prototype module which is fully working (missing some of the wires for the Power input as well as the wires to the ethanol sensor):

[steve99]

nice work :-)

the biggest thing holding back opensource is the ability to intergrate the flex fuel sensor to the ecu and tune.

need someone to write code to use an unnecessary sensor input such as evap purge then more code to use the flex sensor data to adjust tune for e%.

[Fiskafan]

Originally Posted by steve99

the biggest thing holding back opensource is the ability to intergrate the flex fuel sensor to the ecu and tune.

Yes, i aggree on that. This Piece of hardware provides the same functionallity as other ECA:s on the market do. It only helps with transforming the 50-150HZ output from the ethanol sensor to a 0-5 volt that can be read by the ECU.

With this opensource hardware you still need a custom flex-fuel tune that is coded to to read the 0-5 volts that the ECA outputs. But, since this hardware works in the same way as for example the Zeitronix ECA does then you should be able to use the FlexFuel tunes that Moto-East and other sells.

I have drawn two basic diagrams on how this one can be used.

• Option 1, Use it as a standalone ECA.
• Option 2, connect it to an existing FlexFuel installation if you want to have the Ethanol Content output available via Bluetooth instead of a additional display.

[rbimdxe]

Literally joined up because of this thread.

In Australia the Zeitronix gear is quite expensive and only slightly cheaper to import it, so this looks like a great option.

However, having never had experience with Arduinos and the like, how difficult would it be to get all the equipment and actually program the ATtiny85 chip? What is needed to program it anyway?

Thanks for developing this

[diodelphi]

good

[Fiskafan]

Originally Posted by rbimdxe

However, having never had experience with Arduinos and the like, how difficult would it be to get all the equipment and actually program the ATtiny85 chip? What is needed to program it anyway?

The easiest way to program the Attiny in this case since the code is built in the Arduino IDE is with the help of an Arduino board like the Arduino Uno. This is a good guide that explains the basics of programing a ATTINY thru arduino: [ame="https://www.youtube.com/watch?v=30rPt802n1k"]How-To: Shrinkify Your Arduino Projects - YouTube[/ame]


The reason for why this Project uses an ATTINY is that it provides a way to Control the functionallity by software. E.g, outputing information on a serial interface etc. Adjustments can be made within the software to make it function differently.


Currently im working on a small windows application that makes it possible to adjust some settings in the board via Bluetooth. The settings would, Min/Max HZ, Failsafe value, Min/Max Ethanol content detected etc. This application would be available in a short while.


Im planning to sell pre-made board and programmed ATTINY:s for the ones who don't have the Tools available to solder SMD Components or programming the ATTINY chip.

[dunit121]

Great project. I can't wait for it to be complete. I'm sure you will sell plenty of these.

I do have a few questions. Is their any way to add a buzzer or alarm of some sort to go off when the fuel is contaminated?

Do you know what you will be charging for one of these boards?

Do you know of some kind of case that these boards will fit in?

Thanks for the great work.

[Xero-Limit]

Really cool to see this. Definitely something we considered but the zeitronix package isn't too bad. You figure the board, components, case & accompanying labor are going to be at least 100 (unless you off-load to china with quantities in the 1000's). Then add the sensor, and two harnesses (display and sensor). Then the display itself. Followed up with QC on components you end up with a price that is not too far off what zeitronix does wholesale. But if you can get the frequency - voltage conversion done for under a hundred there will be a market for sure. What's your total build cost so far?

[Fiskafan]

Originally Posted by dunit121

Is their any way to add a buzzer or alarm of some sort to go off when the fuel is contaminated?

Well. It it is/isn't. All I/O pins are currently in use. The led output could be used for sounding a buzzer instead of having the led signaling the state of the sensor/fuel. Earlier in the project i had some thoughts about a buzzer, but there is a major problem with a buzzer and that is that the sound form it will be very depending on where you place the device. It would be hard to find a good place to install it where the buzzer volume would be correct. Also, there would need to be a way to disable/override the busser since i personally would be very unhappy if it was buzzing as soon as i turned the ignition key on.

Instead of a buzzer, my idea is that the Android app will provide a similar functionality. The plan is that the app can be configured by the user to run in the background and reconnect to the ECA once its powered up. Then the Android app will be able to notify you about contaminated fuel.

Last days i have made some major code changes that makes it possible to control the failsafe output voltage that can be read by the ECU via the bluetooth link. This makes it possible for the user to set the desired output voltage that the ECU would get in case of a ethanol sensor failure or when it reads contaminated fuel (I'm not sure if this is a useful feature or not, but its cool =)).

The App which currently only is built for Windows can also read the current %, Min/Max % detected (resettable from within the app) and configurable timing/Hz compensation to make sure that the % reading is as accurate as possible. - Maybe i'm overdoing it, but i have tried to make the settings that was hard coded within the code earlier to be configurable from an app (saved into EEPROM on the ATTINY) so that the IC firmware doesn't need to be changed.

Originally Posted by moto-mike

You figure the board, components, case & accompanying labor are going to be at least 100 (unless you off-load to china with quantities in the 1000's). Then add the sensor, and two harnesses (display and sensor). Then the display itself. Followed up with QC on components you end up with a price that is not too far off what zeitronix does wholesale. But if you can get the frequency - voltage conversion done for under a hundred there will be a market for sure. What's your total build cost so far?

If it turns out that there is a big interest in this product then i will produce this board in batches and sell.

I have all the tools needed for performing reflow-soldering and such on my own, so no off-loading to china or someone else.

This device will probably never have a fancy display and case. The Display is replaced by bluetooth output since i don't like adding "single purpose" displays in my own car. Also, the ATTINY85 device memory that holds the running code is only 8KB(!), and its about full now so there is no more room available for the code needed for display output since the serial/bluetooth output was selected instead of a display. - Maybe sometime I integrate it in a OBDII devices/display that shows both ODBII and Ethanol information as described in my first post.

Regarding the case... The case will consist of a really simple transparent heat shrink tube =). The idea from the start is that it will be placed behind the dashboard and this can be considered as a more "protected" environment compared to the engine bay. Also, i suspect that the bluetooth signal might be poor if the devices is placed in the engine bay with the engine running, but i have not tested it yet so maybe it would work to store it in the engine bay fusebox.

I will send one of this devices out for testing to a person tuning Nissan:s and he will help me evaluate it. If someone else would like to help with the testing then let me know. I will need a few more weeks for it to be ready for testing.

I have attached a image showing a preview of how the windows app looks in this alpha stage.

[JETFAST]

Nice work! pm sent.

[rbimdxe]

Just seeing if there was any further updates?

[Fiskafan]

Some more work have been done lately and i have now fabricated a couple of boards that will be sent out to some beta testers.

Features that exists in this version of the board is:

• Current Ethanol % and Temperature readings from within the App.
• Min/Max Ethanol % readings are stored in EEPROM which means that those will be stored and updated even if the computer/phone isn't connected.
• Settable "failsafe" voltage (contaminated fuel, broken ethanol sensor) from within the App.
• The "pullup" voltage can now be controlled from within the App, which means that this board can be used as a standalone device or connected in parallel to an existing ECA as shown in the previous connection diagram without needing to solder/desolder the jumper on the PCB.

I still have a couple of boards available that i will be able to ship in a few weeks once i know that the beta testers are satisfied with the tests. - So let me know if you are interested.

Images show the finished board, the windows app and the android app. The layout in the Android app will be reworked in the upcoming weeks. Also, don't bother about the incorrect % reading since this was due to the signal generator used when testing: