Eggtimer Rocketry Eggtimer User Manual page 16

might want to increase its diameter, to keep it from "whipping" as the rocket travels along its
path, or better yet use a rail launcher. If you can, you can also shorten the length of the booster
to bring the CG towards the rear; you should check this carefully with a flight simulator program
first before you start cutting, however!
Programming Your Eggtimer
Before you attempt to mount the Eggtimer in a rocket or fly it, you will need to know how the
programming screens work. The Eggtimer can be programmed from just about any USB-
compatible computer using the included USB-serial data cable. This cable has the interface
circuitry imbedded in the USB connector, so it doesn't use up any board space or power on the
Eggtimer. It uses a Prolific PL-2303 serial interface chip, which is recognized as a native serial
port on Windows XP SP3, Windows Vista, and Windows 7, Windows 8, as well as by Mac OS
X and many Linux distributions. The interface is a simple text terminal, VT100/ANSI
compatible. No fancy GUI graphics, but it's fast and easy to use, and free terminal emulator
software is readily available for every OS known to man. We like TeraTerm and PuTTY, but
any emulator will do; however, to download flight data you need to be able to "capture" the data
stream to a file, so make sure your terminal program supports this. If it doesn't, you can get
around it by doing a Copy of the text that gets output to your screen, and doing a Paste into a text
editor such as Notepad.
If you do not already have a suitable terminal program, or you need the USB-Serial driver for the
cable, go to www.eggtimerrocketry.com, click on the Links tab, and you will be directed to a
suitable download location. Note that we try to support non-Windows operating systems since
the Eggtimer is OS-agnostic, however we're Windows geeks so we can't guarantee that we've
had a chance to try every possible configuration (especially with Linux!)
Before you try flying your Eggtimer, we recommend that you play around with the programming
screens on your workbench, until you are comfortable with it. You can't hurt anything, and if
you totally mess up the memory you can always do a Master Reset to clear out all of your
experimental values.
To get to the Eggtimer menu screen, be sure that the power on the Eggtimer is OFF. Connect the
GND, RX, and TX connectors of the USB-serial cable to your Eggtimer, being careful to match
them up to the terminals so marked, then plug the USB end into a USB port on your computer.
Launch your terminal emulator program, configure the serial port for 19,200 baud, and connect
to the serial port. Power up your Eggtimer, and you will see this screen. You will also hear a
beep-beep sound to let you know that you're in programming mode. When you do, hit the Enter
key a few times, this will let the Eggtimer know that you have a terminal connected and you're
not ready to start a flight. Note: Be sure to hit Enter within 30 seconds of the beep-beeps, or it
will go into flight mode and you'll have to reset it again to get to the programming screen.
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