Megasquirt, adding a VSS

nbuscemi · Post by **nbuscemi** » Mon Jan 25, 2021 8:18 am

After much trial and error I finally got a semi-working (still buggy) Vehicle Speed Sensor (VSS) feeding my Megasquirt 2.

Here is the tone ring. The ring itself if from an unknown source. It has 54 teeth and is welded to a hand made hub. The wheel is mounted using two of the CV bolts (of which are longer to compensate for wheel thickness).

The sensor is from a 2000 Ford Powerstroke (7.3L) Cam position sensor. This sensor has three wires and produces a square-wave that increases frequency as the wheel spins faster.

This is the "control module". The blue PCB is a voltage regulator (overkill for this project) that produces 5V. The green PCB is a Frequency->Voltage module. It takes the square wave from the wheel sensor and converts it a linear 0-5V that the Megasquirt can use.

On the MS2 itself, I am using ADC6 as a spare input. The only issue I have right now is the fact that Amazon sent me the wrong F->V module (0-10KHz) so the resolution from the sensor is rather poor. I have a 0-3Khz module in route so this should improve the VSS output.

I just wanted to share with the group.

-Nick-

panel · Post by **panel** » Mon Jan 25, 2021 11:35 am

Amazing work as always Nick ! What are you using this feature for ?

Schweg · Post by **Schweg** » Mon Jan 25, 2021 2:11 pm

I got pretty good speed resolution on mine with only the 5 axel bolts. I would imagine the tone ring will work more better.

nbuscemi · Post by **nbuscemi** » Tue Jan 26, 2021 4:38 am

panel wrote: ↑Mon Jan 25, 2021 11:35 am Amazing work as always Nick ! What are you using this feature for ?

Thank you! I wanted MS to see vehicle speed for datalogging and to display on my LCD dash board.

I was using the CV bolts in my first design, and it worked well at medium to high speeds but was twitchy at lower speeds. I wanted something with higher resolution. 90% of my "ideas" are stolen from modern OEM setups. The hard part is getting them to work on a 50+ year old car.

-Nick-

Schweg · Post by **Schweg** » Tue Jan 26, 2021 4:32 pm

nbuscemi wrote:
panel wrote: ↑Mon Jan 25, 2021 11:35 am Amazing work as always Nick ! What are you using this feature for ?
Thank you! I wanted MS to see vehicle speed for datalogging and to display on my LCD dash board.

I was using the CV bolts in my first design, and it worked well at medium to high speeds but was twitchy at lower speeds. I wanted something with higher resolution. 90% of my "ideas" are stolen from modern OEM setups. The hard part is getting them to work on a 50+ year old car.

-Nick-

Are you not getting speed from your gps? Also which gps are you using?

Any before shots of the ring adapter?

Sent from my iPhone using Tapatalk

nbuscemi · Post by **nbuscemi** » Wed Jan 27, 2021 5:02 am

Yes, I'm still using the GPS... for now. I will use it to help calibrate the VSS but it will eventually be removed. When the GPS worked, it works perfectly. The component in Tunerstudio that accepts the GPS signal works flawlessly. The issue is with the dongle and its my fault. I purchased a cheap one from Amazon.

It would take forever to connect to a satellite. I wanted something more consistent and reliable.

Sorry, no pictures of the tone ring / hub. I kind of made it up as I went.

-Nick-

Max Welton · Post by **Max Welton** » Wed Jan 27, 2021 2:05 pm

FWIW, I use Shadow Dash MS on my Android tablet to both datalog and display. Speed is supplied by the tablet's GPS.

20210127_150039.jpg

https://youtu.be/1nmcrYU_K-Q

Max

Schweg · Post by **Schweg** » Wed Jan 27, 2021 2:46 pm

I was afraid to click the link! I have the same gps and have / had the same hopes of using it.

Guess I’m going to look at a similar option to what you have for more low speed accuracy.

Thanks for the info!

Sent from my iPhone using Tapatalk

nbuscemi · Post by **nbuscemi** » Thu Jan 28, 2021 4:47 am

Schweg wrote: ↑Wed Jan 27, 2021 2:46 pm I was afraid to click the link! I have the same gps and have / had the same hopes of using it.

Guess I’m going to look at a similar option to what you have for more low speed accuracy.

Thanks for the info!

Sent from my iPhone using Tapatalk

This is the dongle that Efianalytics recommends. If I had spent the money purchased this instead of that cheap one, then I probably would have never messed with the VSS setup.

-Nick-

Schweg · Post by **Schweg** » Thu Jan 28, 2021 1:05 pm

I’m cash poor and time rich so the VSS option is very interesting. I would also like launch control so monitering driven vs not so it’s all practical in one way or another

Max Welton · Post by **Max Welton** » Thu Jan 28, 2021 1:21 pm

nbuscemi wrote: ↑Thu Jan 28, 2021 4:47 am This is the dongle that Efianalytics recommends. If I had spent the money purchased this instead of that cheap one, then I probably would have never messed with the VSS setup.

https://www.amazon.com/Qstarz-BT-Q818XT ... 910&sr=8-3

-Nick-

nbuscemi · Post by **nbuscemi** » Sat Jan 30, 2021 11:00 am

So I finally had a chance to test drive the car with the VSS setup and the new Frequency to Voltage converter (0-3KHz). I had my GPS running at the same time for verification and the VSS was impressively close. Maybe 2-3 mph off from what the GPS was showing. My only gripe is that the read out on the dash is a bit twitchy as the MS is receiving a raw input, no filtering or buffering, but I can live with it. Perhaps one day my arduino skills will be enough to create a signal conditioner.

Hopefully the group can get something out of this project. I'll post updates if I make any changes or upgrades.

-Nick-

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