User`s manual

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Reset Pads (RST)
When shorted, the Reset terminals put the Eggtimer TRS “on hold”, i.e. resets it so that it does
nothing. When it is in reset mode all outputs are held low, so this is the “safe” mode when
multiple deployment systems are used; they cannot be triggered while the Eggtimer TRS is reset.
This can be used to disable Eggtimer TRS while it’s sitting on the pad for a long time, and can
be released shortly before launch. Although the flight computer side is suspended, the GPS
module will still be running and tracking satellites, and the transmitter will be sending out your
NMEA positional data.
When the reset switch is opened, the Eggtimer TRS begins the startup sequence. You will hear a
continuous slow “beep-beep” sound as it tries to pair up with an Eggfinder LCD receiver. If it
can’t find one, you’ll hear a faster “beep-beep” for another 30 seconds as the programming
screen is displayed through the data port and it waits for input from the data port. If it doesn’t
see anything, you must be on the pad waiting to fly, so you’ll hear a long beep, and after
approximately 10 more seconds the Eggtimer TRS begins taking altitude readings and recording,
and chirps until launch to let you know that it’s ready for flight.
If you are NOT going to be using an Eggfinder LCD display receiver, we recommend that you
use some kind of switch or jumper to short the Reset pads while at the RSO table and on the pad
prior to launch. This acts as the equivalent of an “ON/OFF” switch, but does not power off the
GPS module. This is important, because you don’t want to turn off power to the GPS or it will
lose its satellite data and have to reacquire the fix, which may take 5 minutes or more to
reacquire in some (rare) cases. If you ARE using an Eggfinder LCD receiver, the flight sequence
won’t start until you arm it remotely AND both deployment channels have passed the self-test,
so you do not need to use the Reset pads if you’re using one.
The Reset terminals are also used to update the firmware on the Eggtimer, see the instructions on
the Eggtimer web site ( www.eggtimerrocketry.com ) for details.
Note: When you first get your Eggtimer TRS, the flight memory is NOT
initialized. Please see Appendix A for instructions on how to clear the flight
memory by performing a Master Reset. You will need to do this before you can
program or fly the Eggtimer TRS, or unpredictable results may follow!
A Note on Wiring
The Eggtimer TRS is designed to have the wires directly soldered to the board. This allows you
to choose whatever method of terminating the connections you want: barrier strips, solder
directly to the switches, etc. We’ve found that simply wire-wrapping the igniters to a tinned
“pigtail” wire soldered to the board works very well for smaller rockets. By soldering the
pigtails to the board rather than having screw terminal blocks, you eliminate the possibility that
the wire may work loose from terminal blocks in flight.
We recommend using #22-#26 gauge wire for wiring to the Eggtimer board, we like to use the
#24 gauge stranded wire that’s found in Cat-5 network cables. It’s cheap, easy to find, and just
the right size. It’s also twisted together in nice solid-striped pairs, so it’s easy to tell the “+”