QSI Back EMF in the Q1a Upgrade
firmware.
QSI Yahoo Group message on 01 Sep 06.
Rick
asked ,
>>>
It sounds like BEMF is not included in the upgrade chip, but instead RTC?
Calibrated
Speed Control is not included in the Q1a upgrade firmware. But all Q1a firmware
measures BEMF to determine the locomotive's speed, and the measured BEMF is
used in the RTC control loop. The use of BEMF in QSI locomotives has been
discussed before on this group.
Copied
below is the message 3001 that Gerry wrote
>>>
Is there a way to further reduce starting speed?
Try
decreasing the value of CV56.5, RTC Minimum BEMF. See page 167 of the Quantum
DCC Reference Manual, version 4.0.2, available at:
http://qsisolutions.com/pdf/q_dcc_man_402.pdf
Gerry
Pruss
QSI
---
In
There
seems to be some confusion in regards to the use of BEMF in QSI equipped
locomotives. Hopefully I can clarify the matter in this note.
All
QSI equipped HO locomotives use BEMF voltage to measure the speed of the
locomotive. One or more pre-production models of each of these locomotives are
calibrated at QSI to map the BEMF voltage to scale MPH.
The
BEMF to SMPH mapping is used in a variety of ways in all locomotives,
including:
(1) To determine the amount of doppler shift.
(2) To determine whether the locomotive is
quickly decelerating so
that the brake
squeal should be played.
(3) To determine that the locomotive is
moving or stopped.
BEMF
is also used to determine the chuff rate in steam locomotives.
All
the above uses of BEMF are present in all QSI equipped HO locomotives and have
never been disabled.
What
has been "disabled" is the use of BEMF to try to maintain a constant
locomotive speed. QSI equipped models which support Calibrated Speed Control
try to maintain the BEMF which maps to the SMPH corresponding to the DCC
throttle speed step. For example, if the throttle setting were at 10 the
locomotive would attempt to maintain a BEMF which maps to 10 SMPH.
It
is this Calibrated Speed Control feature which has been "disabled".
The
legal issue does not really have anything to do with BEMF. It is the Calibrated
Speed Control. It does not matter if BEMF or a optical
or mechanical cam is used to measure the speed. The legal issue is maintaining
a constant speed based on a throttle position communicated digitally to the
locomotive.
As
far as you model owners are concerned, the Calibrated Speed Control feature has
been REMOVED from the firmware. QSI deliberated whether or not to keep this
feature in the firmware in a disabled state to be enabled later by some
mechanism, but our lawyers advised against this. If one of you clever guys
actually discovered the enabling mechanism and posted the mechanism on the
internet, then it would be as if we had not disabled the feature in the first
place.
From
my point of view as a software developer, the Calibrated Speed Control feature
is DISABLED. The feature exists in the source code for the firmware and I can
enable/disable it at will for each firmware build by defining/not defining a
compiler flag. When the compiler flag is not defined, the source code for the
feature is skipped by the compiler and the executable code for the feature does
not exist in the resulting firmware module.
It
is often hard to communicate subtle distinctions such as the difference between
"disabled at compile time" and "removed from the firmware",
but hopefully you can see the difference.
Will
future QSI equipped locomotives include Calibrated Speed Control?
I am
told not until the legal issues are settled.
However,
the issue of Calibrated Speed Control is becoming less and less important to
QSI. We believe we have a much more prototypical control mechanism in Regulated
Throttle Control (RTC). Calibrated Speed Control is roughly equivalent to
automobile Cruise Control, where the automobile attempts to maintain a constant
speed up hill and down hill, regardless of load.
Do any modern Diesel or Electric prototypes have Cruise
Control?
RTC
operating under Analog DC has been available in all version 6 firmware modules.
With
the Quantum Upgrade Program, RTC operating under DCC will also be available.
Gerry
Pruss
QSI
See
message 3001
http://groups.yahoo.com/group/QSIndustries/message/3001