Missile Works PET2+ User Manual And Instructions

System Overview

The PET2+ provides a highly advanced and versatile dual-event timing control system targeted for
high power rocketry. The design of the PET2+ utilizes a RISC microcontroller with a precise internal
factory-calibrated 4MHz system clock for accurate and reliable event timing control. In addition the
PET2+ uses a 3-axis "micromachined" accelerometer to detect specific inertial events during flight.
Some of the applications that can be achieved with the PET2+ timer include:
· Precise booster separation and sustainer ignition of multi-stage composite powered rockets
· Ignition of secondary composite motors after primary motor ignition for airstarted boosts
· Fail safe backup and redundancy of primary rocket recovery control systems
· Triggering a camera shutter, audible/visual tracking device, or other electrical devices
General Specifications
Arming Mode Inertial/Breakwire
Dimensions 1" W x 3.15" L
Inertial G trigger range 2-5 G's
Output current (sinking) 3A @ 0.5 sec
Handling Precautions
·Always handle in a properly grounded environment. ESD damage is not warranted.
·Never touch/handle the unit when it is armed and connected to live pyrotechnic charges.
·Allow the unit to adjust to ambient temps prior to arming/flying, and avoid extreme temps.
·Never arm the timer and then load your rocket onto the launch rail. Arm ONLY when racked.
·Always prepare your rocket and timer system components with the unit powered off.
All user input and output connections are made to the compression terminals as shown. These
terminals include: Battery (logic and/or pyro power), Breakwire (for a N/C wire loop or switch), and
Event1/Event2 (for external pyro events or controls). All terminals are marked on the board silkscreen
for reference.
User Manual and Instructions
PET2+ Programmable Event Timer
Version 2.0
Battery/Power range 6-10 VDC
Continuity current 9μa @ 9V
Nominal Battery load 6-14ma
Weight 17 grams
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Note: Before using the PET2+, familiarize yourself with the location and designation of all the
user connection terminals, pushbutton controls, and with the audible feedback and LED
functions. These functions, operations, and connections are covered in subsequent sections
of this manual.

Pre-Flight / In-Flight / Post-Flight Modes of Operation

The PET2+ has several distinct modes throughout the course of its operation during flight. These
modes of operation are easily identified by the function of the piezo and the LED.

Power-up mode

When power is first applied to the unit, it will provide a continuous 2-second chirp to indicate it has
been switched on. During this 2-second chirp the LED will be solid

Accelerometer initialization mode

After the Power-up mode, the unit goes through a 10-second accelerometer initialization start-up
delay. The LED will flash slowly in YELLOW
of the device and establishes the initial orientation and inertial references.

POST (Power Up Self Test) Verification / Error Chirp Mode

The PET2+ performs several sanity checks after initialization mode based on its current configuration
to ensure that the rocket and timer are oriented properly and within allowable launch angle and
calibration limits. If using the Breakwire trigger, this input is also checked for a proper "closed loop"
condition. If the unit detects no problems, no mis-orientation, and no mis- configuration, it will arm
both of the event timers and transition immediately into Launch Detect Mode.
If the PET2+ detects an error during Verification Mode it will NOT transition into Launch Detect mode.
Instead it will sound an alarm tone (buzz) and continuously chirp and flash
CODE to indicate what specific error condition was detected. DO NOT MISTAKE AN ERROR CODE
CONDITION for flight readiness and valid continuity feedback and inadvertently launch your rocket.
The error codes are as follows:
Error Code Error Condition
1 X-axis triggering and off-axis or off-cal limit
2 Y-axis triggering and off-axis or off-cal limit
3 Z-axis triggering and off-axis or off-cal limit
4 Auto-axis detection and no valid axis/orientation detected
5 Breakwire triggering with initial open circuit

Launch Detect mode

When all previous modes are complete, the unit transitions into launch detect mode. The piezo and
the GREEN LED indicate the continuity status of the Event 1 and Event 2 output terminals every
second as follows:
Status Code Status Condition
1 Long Beep/Flash No continuity on Event1 or Event 2 outputs
1 Short Beep/Flash Continuity on Event 1 output only
2 Short Beeps/Flashes Continuity on Event 2 output only
3 Short Beeps/Flashes Continuity on both Event 1 and Event 2 outputs
The unit also monitors the accelerometer and/or Breakwire input in order to determine the launch of
the rocket. After this event, the unit transitions into timing operation mode.
RED.
while in this mode. This delay period allows stabilization
YELLOW with an ERROR
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