P-Mag capability demo

Moving to the 21st Century with my airplane's ignition system has brought some benefits...

I built this simple LCD display that ask the P-mag to start streaming ignition data upon startup and then parse the data and display it on a simple 4x20 backlit LCD screen.

The results are shown below. I am not going to go into details on how and what it takes to do this because I do not want to have this compete at all with the EI Commander that Bill Repucci has developed. My device only monitors the P-mag. The total cost to go from P-mag to what you see in this video is $44.45 and over half that is the LCD (no I am not planning to sell them)...

If you are a tech geek and would rather play with electrons than eat, build you one but if not, get the one that Bill Repucci sells. Also buy his if you want to control the P-Mag (that could be expensive if you screw it up playing around with a device like this)

Disclaimer, the data displayed in this example is strictly sample data only and does not mean anything!!!

http://www.youtube.com/watch?v=Bo5HLxaXPbQ

Brian,

That is really nice.

Brantel said:

...
If you are a tech geek and would rather play with electrons than eat, build you one but if not, get the one that Bill Repucci sells. Also buy his if you want to control the P-Mag (that could be expensive if you screw it up playing around with a device like this)...

Click to expand...

Thanks for that and I caution you and anyone else who wants to play with the E/P-mags. It is very easy to issue a command that can either shut the E/P-mags off or screw up their timing.

We spent a lot of time working on the EICommander so that it wouldn't shut your ignition down in flight and if you wanted to make timing changes, you had to step through them, one notch at a time.

Before reading on below...head Bill's warning above. I am not responsible if you screw up your ignition!!! Keep in mind that my project is for MONITORING only and other than commanding the P-Mag to go into stream mode, I do not write anything to the P-Mag. If you decide to write to the P-Mag, make sure you know what you are doing!!!

I have talked to Bill and he is fine with this as a personal project and we agree that this fun project and his EI Commander are different enough that it should not impact him so here goes:

This thing is self contained and can run off of a 9 volt battery or lighter plug or ship power. It all will fit in a project box the size of a pack of cigarettes.

Emagair already has a free software program that will run on a laptop that monitors their P-Mag but for me that is too big and bulky and a real pain. Not to mention hard to see outside in the bright light.

Here is what I am using:

An Arduino based microcontroller board, very inexpensive and very powerfull
A LCD117 Serial LCD microcontroller board, very inexpensive and has a great built in library for the serial LCD screens
A TTL to RS232 converter board, required and cost nearly nothing
A 4x20 Blue LED Backlight Serial LCD screen, awesome and inexpensive
The above and some code and the sentence structure/command codes from EMagAir is all you need to make this thing work....

That is it......simple hu??

I will answer any questions I can. I am not at liberty to give out the command codes or sentence structure provided to me by EmagAir. If you want em, contact those guys yourself.

Once I test this code for a while, I might be persuaded to load it onto your Arduino for you but I will not give out the source code since it contains the command codes and sentence structure.

This was a "for fun" project for me and I do not intent or want to make money off of it....I have another fun project in store for the Dynon!!!

Emag + Dynon

Brian - that is very cool!

If we could only convince the guys from Dynon to display the PMag params on the EMS we would be really talking. Better yet, allow a EiCad-like interface from the EMS!

I know, I know, it might be dangerous - but it would be cool!

Brantel said:

That is it......simple hu??

Click to expand...

Ummmmmm, yeah, simple. So simple that only you and Bill have done it.

No worries about ME sending commands to my Pmags

Erich

The guys at EmagAir have stated that they have made their protocol available to the EFIS makers but as far as I know none of them have took that ball and ran with it. Even if they did not want to program the P-mags, they could display the data like I am only in a graphical way. That would be kid stuff to them....

petehowell said:

Brian - that is very cool!

If we could only convince the guys from Dynon to display the PMag params on the EMS we would be really talking. Better yet, allow a EiCad-like interface from the EMS!

I know, I know, it might be dangerous - but it would be cool!

Click to expand...

erich weaver said:

Ummmmmm, yeah, simple. So simple that only you and Bill have done it.

No worries about ME sending commands to my Pmags

Erich

Click to expand...

It really is simple (ok the code is not trivial but the hardware is!). I took a pic of what it takes to do this. The hardware is available for the most part fully assembled but it is easy to put it together out of kits or raw parts. There are many versions of the uController boards out there and mine is not the most basic one. You can get em even more bare bones depending on what you need.

Here is my setup:

The white board on the breadboard is the uController, the red board attached to that is the TTL to RS232 converter board.
The LCD can be remote mounted or not. It has a daughter board on the back of it that contains the controller for it.



The age of that breadboard makes me start to feel old!

Here is a really bare bones version of that same uController board that is available:

Protocol?

Brian, that is really cool! Is the communication protocol available somewhere?

-Chris

It is just ASCII text streaming out of the P-Mag. The command codes and structure are available from EmagAir. I am not at liberty to share those directly.

Lots of people are asking where to get these parts....

I bought all mine thru http://shop.moderndevice.com/

Their stuff seems well thought out and works great.


uProcessor Board

4x20 Blue Backlit Serial LCD

LCD117 Daughter board/processor for the LCD

TTL to RS232 adaptor board

If you want to program over USB, you will need this USB BUB board. Not required as you can also program over the serial adaptor as well.

Note: Most of the above is available in raw components, as well in kit form and fully assembled and tested. The price for fully assembled and tested is a little more but not much....
Lots of options out there...

Έλληνας για μένα.

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I had a few flights this weekend with the Pmag display and the results are very promising.

The Pmag display is plug and play, plug in the Pmag serial line, add power and it just works. The Pmag display automatically negotiates with the Pmag and puts it into data stream mode.

Most of the data points are working very well. I have sent the following to Tom and Brad at EmagAir. There are a couple more questions about their data format I need in order to finish this up 100%...I put ???? in place of the command codes since I am not at liberty to disclose those.


This is where this is at at the moment. I will shoot some in flight video once I get answers to the above questions....

I can see eventually being able to send text messages to your ignition from your i-phone and asking it how the engine seems to be running. At an advanced stage, if the ignition thinks something doesn't seem right, it could send you a priority text advising of what it thinks is wrong. Finally you can go the full AirBus route and have it fly the plane from takeoff to landing; all that you'd have to do is text it before takeoff with where you want to go. Just don't send it any text that might not agree with what it's doing, as it just might totally takeover and eject you. HAL! HAL, do you hear me?

Not sure where you are picking up RPM out of, but be aware that the RPM out of the RS-232 data stream is not 100% accurate. We ran into this with several customers that had their laptops connected to the Pmag and the RPM indicated was different than what our EFIS was showing. Talked to Pmag and they said the indication out of RS-232 doesn't have a very fast sample rate and is subject to error.

I flew with it the other day and it is accurate enough for monitoring purposes. In a steady state, the P-mag output always matched my Dynon 100%. The RPM out of the P-mag is displayed in their EICAD program with a resolution of 10 rpm. The serial data has it in a resolution of 1 rpm and I am displaying it that way. The EICAD RPM display can be wrong by a significant amount due to rounding errors. I do not round the RPM display....

The rate at which the P-mag sends data is about once a second so if you are rapidly changing RPM it will not keep up.

Again this is for monitoring purposes and is not intended to replace a normal RPM readout. I display it just because it is there in the data stream.

Where to get RPM

Brantel,

What are you using to get RPM data to the Dynon? I will have a dual P-Mag setup and I thought I could hook up the wire from the Dynon to the P-Mag to get RPM sent to the Dynon 180 (I assume you just use one of the P-Mags for this). Are you saying this is not accurate, or is there an RPM connection and also RPM data sent via the serial signal? Thanks for any help?

Also curious if there is a need for a Hobbs meter with the Dynon products.

Brantel said:

I flew with it the other day and it is accurate enough for monitoring purposes. In a steady state, the P-mag output always matched my Dynon 100%. The RPM out of the P-mag is displayed in their EICAD program with a resolution of 10 rpm. The serial data has it in a resolution of 1 rpm and I am displaying it that way. The EICAD RPM display can be wrong by a significant amount due to rounding errors. I do not round the RPM display....

The rate at which the P-mag sends data is about once a second so if you are rapidly changing RPM it will not keep up.

Again this is for monitoring purposes and is not intended to replace a normal RPM readout. I display it just because it is there in the data stream.

Click to expand...

My RPM display on the Dynon is fed from the Tach signal of the P-Mag on the right side and the P-Lead thru a resistor of the regular mag on the left side. Has nothing to do with the serial output from the P-mag...

If you have dual P-mags, you can hook up both sides to the Tach signal on each P-mag and be Golden.

With a dual P-mag system, you really only need to hook up one side since the tach signal is there even when the P-mag P-lead is grounded. Nothing wrong with hooking em both up though...

The RPM is also output over the serial output in the serial stream.

I have found the tach signal very accurate and the serial RPM accurate enough.

The Dynon has a built in Hobbs meter. No need for an external one.

One More Tach Question

I have on P-Mag and one Slick. Is there any reason to pick up the tach signal anywhere EXCEPT the P-Mag. My understanding is the only time it doesn't put out a signal is when it's not powered. Seems like the only time that will happen is very low RPM's and the master is off or the breaker pulled.

No reason that I can tell.. I did both just because I was too lazy to remove the other one that was already connected to the left mag....

Mag Failure

I am not interested in programming electronic mags, I just want to know that BOTH are working and if one fails I am advised. I don't want to unknowingly be flying around on one mag.
Is there a simple monitoring system available?
Jim Wright

Jim,

Bill's EICommander is the only commercially available device I know of.

One should be able to build a simple dual channel uController project to do what you want.

Update?

Brian,
Do you have an update on your PMag LCD Monitor? Did you figure out what MAP was?
Are you monitoring a single PMag or Dual PMags? Got a picture of it mounted in your panel?

Dan

Yes, mine works great. It is setup to only monitor one because one P-Mag is all I have.

MAP is manifold pressure scaled across a 0-31 range.

Mine is a portable unit not panel mounted.

If you want a panel mounted one, Bill's EI Commander is the way to go. His is way more advanced and can also control the ignition. He can also do dual P-mags.