There are two kinds of serial interfaces in most single chip microcomputers. SPI and
UART/USP.
SPI is the simpler of the two but it is unsupported in tablets, cell phones and PC's
of all kinds. The so-called "terminal" programs that run in these devices requires
data in ASCII form. There are three different "terminal" programs for my wife's Asus
Transformer tablet alone. Look it up. Unfortunately, I think, Tracy is using SPI to
send data to his EM-2. To get that data into a PC I think would require another
single chipper to reformat the data to ASCII and send it out a RS232 or USB interface.
Now, what I am doing in this EFI design is converting the binary engine parameter
data to ASCII format in real time and sending that out the RS232/USB.
Once it is in the PC and saved to a hard disk file it can be read directly as a
spread sheet csv text file. That is a human readable file where the numbers are
separated by commas. AKA "comma delimited file". It then becomes a piece of cake to
write a QB or VB program that displays the file in some sort of a graphic form. Or
one can load it into a spread sheet and let the spread sheet plot the data. The late
great Mistral had all that worked out in their EFI system.
Here is an example of the data from the Mistral Turbo-Piper crash.
Be careful with those cheap car mufflers on rotary powered airplane.
If you have one on there now inspect it with a bore scope (home depot) on a regular
basis.
Paul Lamar
Paul,
Most uC can handle SD [card] interface.
Pretty simple to have write the data to a SD card, using a FAT16 file format. Pop
the card out, and use a SD card reader in the PC.
I'm still thinking of using Ethernet connections due to the electrical isolation.
Solves a lot of issues if you do a data dump between aircraft computers and Home PC's.
1500V isolation is more than adequate, one reason the new SAE diagnostic port will be
Ethernet.
Tom W
I don't have a SD card interface in the AT89S2853. (AVR 8051).
I have one in the ARM. The ARM also has an Ethernet connection.
I want to display the engine data on the tablet or notebook LCD display mounted on
the instrument panel in real time. When you need it as you are flying around. That is
what Tracy does with the EM-2 but it is very limited display IMHO.
No pulling out of SD card and plugging it in :) It is simple to use the note book
display as it can run QB or VB and talk to the EFI directly. In QB it is real simple
as you can use the ON COM hardware interrupt but that means you are running DOS.
I have an old Lenova X61 that is either a notebook or a tablet depending on how you
twist around the LCD touch screen. Great for mounting it on the instrument panel. It
has system 7 on it now but it could boot DOS no problem. Of course the touch would
quit working I think. I have installed DOS in the past on old notebook computers.
DOS is the closetet thing to a real time OS with direct hardware access as one is
likely to find. No scheduler.
I am a simple man :)
Paul Lamar
Paul,
Ethernet buffer management is a nightmare for simple stuff like this.
Don't go down that route. You have to break down the data into
packets, keep them in sequence, ack for each packet, do
re-transmission, etc. then re-assemble them into a single packet. It
it like re-writing the entire TCP protocol in BASIC, not to be taken
likely, and forget about assembly for this purpose.
RS-232 is a current loop interface with build in isolation. Usually
optical isolation with chips like MAX232. SPI is not appropriate
because of lack of protection. It is OK to be used within a single
system. Not if you have many things on different power supply and
potential sparks from static build up.
It is really simple to convert byte data into ASCII with Basic. I
think a simple print statement would do the trick.
Henry
Thanks for the tips Henry. I have all the parts ordered and I am about to order the
PC board but I had a better idea for the tach. So the board needs more work.
Paul Lamar
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