Appendix A. Configuring the CL system for
IMPORTANT - "Pot-less" mode is now the default
mode for the system and all BLDRV-12/24 cards and newer CL_SPU +
BLDRV2-24 cards are supplied preset for this
In its original configuration the CL system used
game-controller joystick card potentiometers to report control axis
position (see the standard system
This potentiometer data was required for the power-up calibration of
the BLDRV-12/24 driver cards, and also as control position input to
the flight simulator software.
For systems using BLDRV-12/24 driver cards with
dsPIC v35 and 20X v28 (or later) the system can now be
operated by default WITHOUT potentiometer position data on the main control
axes. This allows the control mechanisms to be built without
position reporting potentiometers - a significant simplification of
the build. Instead control axis position is derived from the motor
encoder position and is sent directly to FS by the BFF CL Software
v1.1 (or later) via the FSUIPC control input offsets.
The "potentiometer-less" system wiring
Although this produces a simpler system, it does
mean that control input to FS is only available when the CL system
cards are powered-up and calibrated and the BFF CL Software is
running. When the CL system is inactive there will be no control
input to FS from the FFB flight controls. A separate simple joystick
configured as a standard game-controller input to FS might prove
useful for controlling FS in circumstances when the CL system is
inactive. So long as the output from this joystick is clean (no
jitter) FS will ignore it whilst it is not in use.
To configure the CL system for pot-less operation
the driver cards must be pre-set, and then a configuration change
made to the CL software background process settings. Note all
BLDRV-12/24 cards now supplied are by default configured for
pot-less mode operation.
"Potentiometer-less" operation configuration steps
- If required - Pre-set the driver cards for
"potentiometer-less" calibration. This is a once-only
procedure carried out using the BFF Driver Test App v28+.
Once set, the cards will be able to complete their power-up
calibration without the presence of live game-controller
joystick position data. Not required for new cards - they are
already pre-set for this mode.
See section 10 of the
BFF Driver Test App user guide for details of the procedure;
it is a simple procedure carried out on each card individually.
- Set the BFF CL Software for pot-less
operation. This will tell the CL software to read control
position data from the driver cards and write it to FS via
FSUIPC. The position data is written directly to
the FS control offsets WITHOUT additional calibration, as a
result the control input to FS is linearly proportional to the
drive motor rotational position. Usually (depending on the
flight control mechanics) this also means the control input is linearly
proportional to stick position.
To make the settings run the Configuration Manager and
select Tab 5 Item 1 "Use Motor Encoder Positions". Click
the Apply button.
Then set Tab5 Item 25 = 1 (Fixed x10 resolution enable).
Save the settings to file.
In operation the CL software will then check the driver cards for
valid firmware and if confirmed will proceed to read control
position from the cards (encoders) and write to FS via FSUIPC. A
healthy background process loop rate (50 Hz or ideally higher) is
required to minimise lag in the FS control movement. If necessary in
the Configuration Manager Tab 6 Item 13 Force loop delay
parameter can be reduced to increase the processing rate - but keep
it below 100Hz.
changes made to these settings apply whenever the
CL software runs and so to all aircraft configurations used by the
CL Software thereafter.
IMPORTANT If you are swapping an existing system
over to "pot-less" operation remember to remove the unused joystick
axis assignments in FS. If FS "sees" additional joystick control
inputs at the same time as receiving CL position instructions the FS
controls will jitter.
Although pot-less operation removes the need for
potentiometers on the main control axes, a joystick card will still
be required for the trim inputs to the CL system. These can be by
pot or by button - see the section 7.
FS control input calibration in "pot-less" mode
When operating in "pot-less" mode the FS control
positions are written directly to FS (via FSUIPC) by the CL software
- this prevents calibration of the FS control response using the
usual gamecontroller or FSUIPC calibration methods. With the BFF_CL_Background process v1.25 or later this calibration can be
done within the CL software.
Please use the Configuration Manager - use
Tab 5 Items 6, 7 & 8 to
set "sensitivity" factors for each of the control axes as required.
These factors adjust the movement response of the FS controls to the
movement of the real controls - read the displayed help tips for more
The settings can be used to either slow or
speed-up the movement of the FS controls with respect to that of the
real controls when operating around the mid-point region.
Inhibiting Flight Control position writes to FSX
when in "pot-less" mode
If the system is set for pot-less mode the control
position writes made to FSX via FSUIPC by the CL system can be
disabled. This allows users to provide their own position feedback
to the flight sim without changing the operating mode of the driver
To disable the position writes from the CL system
go to Configuration Manager Tab 5 Item 27 and set it =1.