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Tim's Universal Timer

picture of TUT-FC timer circuit board

The TUT-FC circuit board

Tim’s Universal Timer (TUT) is designed to do a wide range of timing tasks, with a versatility and programmability that has not been achieved by any other control-line timer yet marketed.

This versatility is achieved in the TUT with a combination of two factors: a greater number of input/output ports (a total of four configurable ports), along with the ability to write custom sequences for the TUT and load them in.

Tim’s Universal Timer comes in three configurations: the original TUT, the TUT-HR, and the TUT-FC. The TUT-HR is a size-reduced version of the timer designed specifically for use in the 2014 World Championships by Howard Rush. The TUT-FC is a cost reduced version that uses the circuit board from a TUT-HR and leaves out some expensive parts.

All three TUTs have the same four I/O ports, processor, and USB communications hardware. The TUT-HR adds a gyroscope, while the TUT has a data logging memory and an accelerometer. Anything that can be done by the TUT-FC can be done by the TUT-HR; anything that can be done by the TUT-HR can be done by the TUT.

Things that have been done with the TUT

The TUT is so very versatile that it is difficult to describe what can be done. So instead, I'll describe what has been done with the TUT. Each of these programs is written in a scripting language that is unique to the TUT, and is designed to make it easy to write such programs -- so if you see that the TUT does almost what you want but not quite, please contact Atomic Zombie Workshop with questions about what the TUT can do.

Howard Rush's FAI Program

The driving force behind the TUT development program was Howard Rush's desire to tweak the behavior of his airplane beyond what was available from an Igor Burger accelerometer-based timer. Howard still wanted to use an Igor Burger timer to control his motor during the main part of the pattern, but he wanted different behavior during the starting and ending phases of the flight.

This was accomplished by with the TUT by writing a custom program. The Igor Burger timer is plugged into one of the TUT ports, and the airplane's ESC is plugged into another. (The other two ports are used for annunciator lights to alert the pilot to the active flight phase).

With Howard's FAI program running, the flight is divided into six phases. Most of the times and throttle settings can be changed using the JetiBox or USB port.

Howard's FAI program uses all four I/O ports in the TUT: one is used for input from the Igor Burger timer, one is used for output to the ESC (electronic speed control), one is used to indicate whether the TUT is taking input from the Igor Burger timer or is using its own internally-generated throttle command, and one is used to indicate the end of the flight, in a manner that helps the pilot locate the motor cutoff in a desirable spot relative to the wind.

This program can use the gyroscope on the TUT-HR to determine the cutoff point of the approach lap. However, the way that Howard Rush set his program up for the 2014 World Championships, the gyro was not used. So one could run this program on a TUT-FC and get the same functionality as Howard did at the World Championships -- but using the gyro is more fun.

Howard Rush's AMA Program

One of the salient features of Howard's FAI program was that the TUT did not provide any shutoff mechanism. This was done because Howard felt that there was an ambiguity in the rules, and he neither wanted to make any waves about the wording before the contest, nor did he want to be challenged on the rule at the contest.

This was not an issue for AMA competition. For AMA competition, Howard wanted to be able to use the TUT to detect a shutoff loop late in the pattern, and enter an approach sequence after a shutoff loop is executed.

The same four I/O ports are used in Howard's AMA program, except that instead of blinking, the "end of flight" annunciator channel is used to tell the pilot that the TUT is armed and ready to detect a cutoff loop.

The initial flight phases are identical: they only differ in the final phases:

Tim Wescott's Test Program

An amusing aspect of the TUT development is that while its primary use is as a timer for electric flight, its developer, Tim Wescott, flies with glow engines. There are a number of initiatives active at the Atomic Zombie Workshop to use the abilities of the TUT to fly better with internal combustion, but Tim has yet to use it in competition.

In order to test the TUT, and Howard's competition programs with a glow-powered setup, and to have a platform for gathering data with it, Tim has his own program which is customized for use with an internal combustion engine.

Like Howard's TUT programs, Tim's uses all four of the available I/O channels. One channel is configured to take input from an Igor Burger timer (although this has never been tried). One channel is connected to a switch, and is used to set the engine needle valve before launch. One channel is used to drive a throttle servo. The final channel is configured to blink an annunciator LED in a similar manner to Howard's FAI program (although it has not been used).

The phases of Tim's test program are as follows:

Fred Cronenwett's Engine Sequencing Program

Fred Cronenwett's engine sequencing program really shows the versatility of the TUT's programming model, because the staff at Atomic Zombie Workshop had no inkling that anyone would want such a thing, yet it turned out to be a fairly simple program to write.

Fred's engine sequencing program is designed to give a realistic engine startup sequence to a multi-motor, electric powered model airplane. With this program, the first motor and the TUT are both connected to the receiver with a Y harness. The other motors (up to three) are connected to the other three TUT channels.

When the throttle is advanced above 5%, the motors start up in sequence, with five seconds between motor starts. When the throttle is cut, the motors shut off in sequence.

Traveling through the phases of Fred's program is more confusing, because the program will go through them in both directions, depending on the throttle setting. Also, if the throttle is suddenly advanced, the program will jump to the final phase.