I have developed a small circuit board that is 2.25" square that directly converts a
SENT signal into two 16-bit analog output voltages. I could probably sell you one
(or some) of these boards. Visit my site http://www.biltronix.com, enter the
Biltronix site and send me an email from there and mention this thread. There is no
information on my site about the board because I developed it very recently.
I use this new board to convert the SENT output of DC-motor powered throttle bodies
with Hella position sensors into analog signals. This allows the valves to be tested
and cycled on existing equipment that was built for products with analog inputs. The
analog signals are easy to capture with Labview or any other common data logger. I
also have developed a very nice small closed-loop controller board/box that operates
the DC-motor type valve assembly. This board/box is used as a single-channel desktop
controller and has been used underhood. The closed-loop controller boards have also
been installed in groups inside larger boxes to cycle multiple parts. The controller
has a dial that you can turn to control the position of the valve. It also accepts
PWM and analog reference signals and it has a PWM status output. My point here is
that the closed-loop controller was built to accept 1 or 2 analog position sensor
inputs, not SENT, but by hooking up the SENT-to-analog converter board, there's no
more problem.
My SENT converter board runs on +6V to 20V and it has reverse polarity protection and
transient protection. It powers the SENT sensor with a regulated +5V output. It
syncs to and reads and analyzes the entire SENT pulse frame. It checks for valid
sync and nibble pulse times, normalizes the nibble pulse times to the sync time, then
converts the nibbles to data. Then it checks the checksum and applies some other
error detection tests as well. If all is well, the data is converted into 12-bit
word values and then loaded into a pair of 16-bit precision DAC's. The voltage
outputs are then buffered and available at a set of plug-in screw-terminal blocks
where you can easily attach wires.
The board has a two-color LED on it that indicates the operating status. If it is
green, everything is running perfectly. If it is red, there is some sort of error
converting the SENT signal (ie: bad checksum, sensor is indicating a fault, data is
incorrect, etc.).
The board also has a serial interface that can be connected to a PC using
HyperTerminal or other terminal application. Using the interface, it is easy to runs
tests on the board (it tests itself thoroughly) and to manually control the two
voltage outputs. There is also an output scaling feature so that you can change the
output range if desired. At present, the board converts every SENT frame in real
time with scaling off but most people prefer that mode anyway. With scaling turned
on, it converts every other frame. I am thinking about adding a "bootloader" feature
so that the end-user can update the firmware from their PC. It is likely that I will
be producing new firmware in the future that will handle different SENT-type sensors.
I presently have firmware only for the position sensor type such as that presently
used on GM ETC.
The board also has a few test points including ground, wave-shaped buffered digital
SENT output, +5V output, +2.5V reference output.
In case anyone is wondering, my SENT-to-analog converter board is based on a 40 MHz
PIC microcontroller that is programmed (flashed) on-board through a dedicated
programming interface or (if supported by firmware bootloader) through the serial
port interface. I designed and built the entire board myself and wrote all of the
source code as well.
To anyone who is interested in this converter or if you'd like me to do some custom
programming for your application, please just go to my site and email me from there.
I won't likely be checking back to this forum.
Cheers
