speedo from vss

[62f100]

i not sure totaly sure how speed is calculated,but wondering if there way to use vss to get the speed.im not to sure my rear ratio or auto trans gears.any suggestions,thank in advance. dan

[dave]

there's a few circuits for this if your search the megasquirt forums.
basically it gets calibrated, since the sensor is on the diff or wheel the actual gearing doesn't matter.

[62f100]

i found a circuit ,but it talks about megatune use .how do i use it in tunerstudio.

[LT401Vette]

Should be the same. TunerStudio supports the MegaTune config files. But a whole bunch more

[62f100]

so ive got to download megatune to make the file to put in tuner studio.could u be more specific,only been doing this a few month.

[62f100]

the only circuit i could find was in "what happened to atirev page?"post.so using this circuit doi hook it to x6 or x7 for just the speedo funtion. do i need two circuits? what files do i need to create?

[LT401Vette]

Not files, but entries into the ini file. That will depend on the the firmware you are using supporting it and reporting it.
The tuning software can not see any hardware ports. To put it on a gauge, the firmware needs to return some sort of data that can represent the input to a hardware port.

So, you really need to check with the firmware. The Extra firmwares are good for having spare hardware pins that they do return an ADC value for in the OutputChannel return. If you get what is being returned in the OutputChannel command, I can tell you what you need to put it on a gauge or in a log.

[62f100]

im running 29y4 . using this firmware &the hz to voltage circuit 0-5v, i think i would set 2.5 v for 60mph given a top speed of 120mph for now.if ive under stood the post the input voltage would go on x6 OR x7.id like to use x7 on my ms1 v2.2 board. using as guage only at this time.thanks for the help, dan

[LT401Vette]

Check the [OutputChannels] section of your ini file. this is the line that captures the input of X7:

Code: Select all

   fuelADC          =  scalar, U08, 26, "ADC",    1.000, 0.000  ; ADC from X7 (second O2 or fuel pressure)

That will read a 0-255 ADC value that equates to the input voltage 0-5 in a linear fashion. But you don't need to do anything with that, it is just a reference to where the data comes from the controller.

At line 3328:

Code: Select all

   Speed = { 70 }    ; Change this to your actual speed @ 2.5V from VSS circuit

Do just what it says.... If you have 2.5 V @ 60 MPH, change the 70 into a 60.

That is all you have to do on MSnS-Extra 29y to have a valid Output Channel for speed if you have a speed sensor circuit on X7.
There are some final calculations, Then the final Output Channel that you would use is "mph"

If you create a new Gauge, and set it's Output Channel to mph you will read from your speed sensor in MPH.

If you want to log your speed, add this to the [Datalog] section of the ini:

Code: Select all

   entry = mph,            "MPH",     int,    "%d"

Now your data logs will contain a field called MPH with your vehicle speed. There are all sorts of things we can do with that in MLV if just more people had speed sensors

[dave]

I thought I would help search it out, since I also intend to be adding speedometer.

http://www.msextra.com/manuals/MS_Extra ... m#addgauge

the often-linked antirev page is dead, but luckily there's an archived one:
http://web.archive.org/web/200708242229 ... tirev.html

[62f100]

thanks for the reply. for the ini change,i change it in "poject name" 29y4 file?im runnin vista os .

[LT401Vette]

yes, change the ini file in the projectCfg sub folder of your project.

[62f100]

ah i see,says the blindman.ur help is great. i read the manaul that says megatune , so i have figure out were that is in tuner,but it becoming clear know.

[62f100]

is the circuit in the extra manual (referenced by daves post)needed if you use the twwo circuit on the antirev post? also in researching this i found a site that had a ford vss vrs discrete interface www.dainst.com/info/circuits/oldVRSstuff and was wondering if this would be better since im using a ford vss?

[62f100]

talked to the guy who made the circuit on dainst site. he said the one he posted are not the best ,to use the one on the antirev post.hopefuly il finish the install of the circuit & try it sometime this week .