Well, I'm excited to discover that I have successfully been able to send the
pressure
altitude reading received from the iLevil 3 AP to the Garmin GTX327 transponder.
As you probably know, the GTX327 accepts altitude messages over RS232
---From a Garmin 480, RS232 from fuel/air Data Computer (if configured with
ALT),
gray code, Icarus, or Shadin.
Looking into the Icarus format, it was very easy to send over my computer's
serial
cable using Putty. This gave me the idea that if I could get pressure alt
---From a source, I could then convert that to Icarus format and send it over
RS232.
I chose the Raspberry Pi Pico to be the 'handler' of this conversation. It
has two serial interfaces that communicate on RS232.
I was hesitant to purchase the iLevil3 due to no information about the output
and
was considering using an MGL Blaze just for a backup/altitude encoder. I did
some testing and discovered there are many options for data output on the
iLevil,
one being 'Data output.' I connected this pin to my RX port on my computer's
serial cable and started to receive binary data. Not easy to read but knew
it had some good info. A quick email to Levil gave me the information needed
to decode the protocol and find the pressure altitude. Armed with this
knowledge,
I wrote a program in Python 3 to read the iLevil data and store the pressure
alt as a variable. Then the program converts that to Icarus format (ALT 12345r)
and sends it to the GTX327.
Also, the iLevil3 (with the GPS upgrade) works with the EchoUAT as a GPS source.
Right now I'm trying to determine the protocol the EchoUAT uses to populate
the pressure altitude over RS232 on COM1. I'm guessing it's GLD90, but not sure
of the message ID or framing.
Other thoughts are with being able to 'export' the live data from the iLevil3,
you can run other instruments like a digital display for ground speed, etc. I
hope this is helpful for someone. Please message/email me if you have any
questions.
In this photo from left to right, first is the ground (connected to both sender
and receiver), the middle is the TX to the GTX327, left is the RX from the
iLevil3.
Here, you can observe the pressure altitude at 515 feet. I've observed that on
the GTX327, the output is also in Icarus format, rounded, but I'm not certain
about the resolution without conducting further testing. I can readily adjust
the program to match this format, but currently, it's reflecting the resolution
that the iLevil is transmitting (1 foot).
--------
Kyle
Europa Tri-gear (under construction)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=513375#513375
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