The plot continues to thicken…
…I think have had an AH MOMENT… but first see the quote from this e-mail thanks to R Denton.
Subject: Solution to the VEX single-frequency problem with two transmitters
Hi, I’m the mentor for FRV-40, a group of mostly home-schoolers from
northeastern counties outside Atlanta. As you probably have read, FIRST
will assign only one frequency to control each robot, but gave no
guidelines for how to avoid signal conflicts between a team’s two
transmitters. Daniel, one of our student members, has figured out a
programming solution for using only one frequency while operating two
Use the EDIT_PT command to turn down the motor ports on each transmitter
that you do not want it to control. For instance, on our first
transmitter currently motor ports 4, 5, and 6 are turned down to zero
percent. On the second transmitter, currently motor ports 2, 3, 7, and
8 are turned down to zero percent. Motor port 1 can be turned down to
zero, but only by the SCALE command, and every time you use EDIT_PT that
command erases SCALE. Our team at least for the moment has chosen not
to use motor port 1; they can control it using SCALE but they don’t feel
it’s worth the trouble and they can get by without it. Daniel thinks
the overall solution is crude, but the more important point is, it works.
Our team also posted this solution on the VEX forum website,
www.chiefdelphi.com/forums/showpost.php?p=368278&postcount=5, (credit to
Daniel). This posting is at the VEX robotics section (it’s not the
official VEX forum).
Best wishes in your robot design, our crew is still sweating out some
critical details. See you in Atlanta.
– R. Denton
I PM’ed Colleen-t190 to give us the skinny on the WPI scrimmage. This is what she said:
As far as I know, but I’m going to double check with folks to be sure, teams used one crystal set because there is only one receiver on the robot side. There are two plug-ins on the field though such that two different transmitters can be plugged in per team.
Now do I know that this works correctly, no. I do not believe anyone tried using multiple transmitters. One of our teams had planned on it, but they were waiting for FIRST to send out the team update on how that would work (apparently they said it would be released Friday). It never got sent so they just made theirs work with one transmitter. It was mentioned to FIRST that the update never went out to which the response was “Oh… it didn’t?”. So I’d expect to see an update on it soon.
I’m heading to campus now and I will ask the people who were actually switching crystals (and will be working VEX staff in GA for that) what the good word is on the topic and let you know.
Now hear is what I am guessing they MAY be doing at in Atlanta… They may be tething teams up to the field and letting the field broadcast the signals. This solves 2 problems, 3 actually, no 4…
- it give them the chance to combine the signals from 2 transmitters with before sending them to a single common transmitter station set to the right frequency for your robot
- it solves the 4 pointy sticks the driver station problem
- it means 1 channel per team - so they would not run of crystal frequencies
- it lets them turn on and turn off your robot! – how were they going to do this with teams directly sending signals to their robots?
I think I have noodled it out. I HOPE FIRST will give us an answer soon. In the mean time, hopefully the work around by R Denton will help.