I've been kicking around some ideas for building an engine control
unit for my gas turbine and have looked into the PIC route using LCD
character screens, etc etc, but the amount of development time
constructing the proto board, having a final board produced,
soldering everything together, and further development to refine the
control just doesn't float my boat all that well.
My professional specialty mainly deals with modification of OEM
engine computers for the Nissan Z-cars and I've got thousands of
hours over the past seven years disassembling code, modifying it,
creating my own EPROM emulation system for real-time tuning, as well
as R&Ding and manufacturing many other bolt-on performance parts, but
of course, all that hard work pays. :)
So I got to searching for any sort of solution for using a PDA with a
data acquision device and finally came across a "budget" solution
that looks promising. Many of the PDAs available have a serial port,
and newer ones have a USB port, which can be converted to a serial
port using an adapter. I came across a company,
www.bb-elec.com
which has a ton of DAQ solutions. And I came up with this device:
http://www.bb-elec.com/bb-elec/literatu ... 3804ds.pdf
It has:
7 channels of 12-bit A/D
4 channels of 8-bit D/A
2 Digital Inputs
1 Digital Output
37 samples per second when sampling all channels (~120S/s for single
channel)
9600baud, 8,1,N communication protocol
Power supply voltage of 12V-18V.
Programming for this device will be really simple as there are only
four commands.
The fact that is has more than enough channels for inputs and outputs
and a reasonable sample rate for controlling/monitoring a GT is nice,
but to top it off, this device is only $89.95 US.
A/D channels can accept inputs from a TIT thermocouple, pressure
transducer, and RPM pickup (using an LM2917 freq to voltage
converter). With expansion capability for four additional inputs
(afterburner temp & pressure sensor for "tuning" the A/B?). Or also
for monitoring oil pressure/temperature? In my case, I am thinking
to use a potentiometer on an input for controlling one of the analog
outputs to handle fuel delivery (pot on a thumb throttle for the jet
scooter). Other fail-safe functions can be implemented as well such
as using a digital output connected to a fuel solenoid to completely
cut off fuel flow, user-adjustable max TIT and RPM with closed-loop
fuel control to prevent overspool or overheating the turbine.
A PDA unit is quite compact and this DAQ device is also rather
small. The DAQ device can be located closer to the engine to avoid
having to lengthen thermocouple wires and a serial cable can connect
the DAQ to the PDA.
I haven't written any code for PDAs but given that many of them are
running WindowsCE or PocketPC, finding a compiler for these OSes
shouldn't be difficult at all, and a program to handle something like
this can be forged over a lunch break.
I'm not looking to reinvent the wheel here so if someone else has
already done this and is using such a system for operating their GT,
I would love to hear from you (and hearing from anyone is always nice
too.:)
Thoughts?
