User`s manual

- 7 -
Programming is performed using a standard VT100/ANSI serial terminal program, connected to
your computer with a USB-serial cable. Since there is no special software required, you can use
just about any computer, running Windows, Mac, Linux, or just about anything else you can
come up with. Flights can be downloaded to a standard CSV-formatted file, and can be
imported into virtually any spreadsheet or data analysis program to produce flight graphs.
The firmware on the processor chip performs real-time data analysis during flights to detect and
report significant flight events such as launch, burnout, apogee, deployment, and landing.
Hardware breakwire support is provided to provide an extra level of redundancy for airstarts, this
ensures that the rocket has indeed left the pad and that a sudden gust of wind isn’t going to trick
the Eggtimer into thinking that it’s reached the launch detect altitude.
Getting to know your Eggtimer
Although the Eggtimer seems relatively simple, you will want to familiarize yourself with it
BEFORE you install it in a rocket, and certainly before you try flying it.
Battery (3V) – Two solder pads, marked “+” and “-“, for connecting the Eggtimer battery.
Typical draw is about 8 ma when running, recommended battery voltage is 3v-4v.
Push Button (ACT) – Performs various actions when pressed.
Indicator (IND) – Glows solid or blinking, depending on the status of the Eggtimer.
Ready Indicator (RDY) – Glows on when ready for launch, blinks when flight is done or the
Eggtimer is in download mode.
Beeper (BUZ) - “Beeps” out status, warnings, altitude, and other important notifications.
Channel A (Main) Deployment (CHA) - Two solder pads, marked “+” and “-“ for connecting
an electric match or other low-to-medium current device. Deployment delay/altitude is
programmable. Maximum 8A current, 30 VDC, 60 W. You can also connect the input for a
standard analog hobby servo to the “+” terminal (along with a 39 ohm ¼ W resistor in parallel)
for non-pyro deployment.
Channel A (Main) Battery (BCHA) - Two solder pads, marked “+” and “-“, for connecting an
external battery for the deployment device (if used). Typically, these batteries are 3.7v LiPo
cells for low-current igniters such as a Quest G2Q2, or 9-12v alkaline batteries for #36 nichrome