Matt,
I set mine up for analog on pin 1.
I used a pot off the 3.3 v supply
Here is the results.
There is quite a bit of variation in the hundreds of volts.
(.01) I need to look at the 3.3 volt supply with my scope to see if
there is any noise on it.
It also takes about 6 msec for the A to D and the print on the screen.
I'll remove some of the characters sent to the screen and see if that helps.
I suppose saving the data on the SD card would take longer than writing
to the screen. We shall see.
Mode 1
SetPin 1, 1 'set pin 1 to analog in
Timer = 0
For x = 1 To 35
data1=Pin(1)
Print data1;
Print " ";
Print " Number of msec =";
Print Timer
Next x
-------------------------------------------------------------------
As I suspected it took a lot of time to display all those characters.
As a matter fact for an EFIS you want to set a 1 second hardware
interrupt and update the screen every second. If it has a noticeable
blink set the up date interrupt to a half second update. Then the time
to send characters to the screen is minimized.
I was curious about how long an actual A to D conversion took so I
wrote this program and connected by scope to pin 19.
Mode 1
SetPin 19, 8 'setpin 19 to output
SetPin 1, 1 'set pin 1 to analog in
start:
Pin(19) = 1 'put pin 19 high
data1=Pin(1) 'actual A to D conversion
Pin(19) = 0 'put pin 19 low
GoTo start
For the actual A to D it took about 450 usec. Then to go back and set
the pin hi again
it took about 50 usec. This is a BASIC interpreter a BASIC complier for
the Maximite would
be nice. Setting a pin hi and low in a Coridium ARM BASIC compiler happens
in one or two microseconds.
The idea for sampling the manifold pressure at the oil injector hole
should be done
just after the apex seal closes off the p-port. This happens about 90 to
110 degrees
after top dead centre. Since the second gen crank angle sensor has two
triggers
one about 20 degrees BTDC for the ignition and a second trigger every 30
degrees.
(24 teeth running at half e-shaft revolutions.)
This allows you to sample the manifold pressure at the same place in the
intake cycle
every time. That should result in a much more consistent mixture setting.
Tracy never told me when he sampled the MP. I suspect it was at random.
In addition
it varied with the turbulence in the intake manifold so everybody had a lot
of trouble tuning Tracy's EFI system. No two system sampled the manifold
pressure in the same place. The Mustang 2 p-port had the oil injector
hole pressure
tap which yielded more consistent data. If sampled at random you had to use
a container to average out the pressure variations. That was a less
accurate way
of doing it.
Paul Lamar
Will the Maximite be able to monitor and change the fuel/air ratio via
the o2 sensor.
Regards Andrew Campbell.
Yes but be aware 100LL aviation fuel kills O2 sensors. I would not use
that as the only sensor to set the mixture. I would still have a MAP
or Mass Airflow Sensor. I would also use the wide band variety and place it
at the end of the exhaust pipe. Aviation rotaries run hotter exhaust as
they are on average a higher percentage of max power.
Paul Lamar
The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
You Tube
http://tinyurl.com/beqqxas
Copyright 1998-2015 All world wide rights reserved.