Water Rocket Servo Timer for Parachute Recovery

[U.S. Water Rockets1]

U.S. Water Rockets officially announces the release of their free parachute servo timer deploy system software. The free ServoChron(tm) software download for the $4.30 Texas Instruments MSP430 LaunchPad board turns it into a servo controller anyone can use. Sometimes referred to by the generic term 'flight controller', the free ServoChron(tm) software creates a launch triggered delay servo timer for staging or recovery mechanisms.

Complete Servo Parachute Deploy Timer for about $10 US!

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Description:
The ServoChton(tm) is a FREE download which you will load into the MSP430 launchpad with free download software and a standard USB cable. With the addition of a servo motor and a launch detect switch, you will have a flexible servo deploy timer for water rocket parachute recovery or water rocket dragster drag chute deployment.

The ServoChron(tm) is based on the MSP430 LaunchPad

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The innovative design utilizes the latest in servo technology to reduce the power requirements to a single LiPo battery! Using a servo motor capable of operating at 3.7V eliminates the inefficient power sapping voltage regulators which would be required to power older 5V servo motors and the associated driver circuitry. The low power requirements naturally mean you can use a smaller battery and save cost and weight!

A single cell servo powers the innovative design

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A few simple connections are all that is required to assemble the ServoChron(tm). The diagram below shows the wiring is so simple that anyone can build the system.

Wiring Diagram for the ServoChron low cost Servo Timer from U.S. Water Rockets

ServoChron_Wiring_Diagram.png (19.22 KiB) Viewed 291 times

The video below gives a brief demonstration of the simplicity of setting up and operating the ServoChron(tm).
[youtube][/youtube]

Technical Information and Downloads:
ServoChron(tm) Firmware Download: http://www.uswaterrockets.com/shared/Se ... _V1.00.zip

ServoChron(tm) Assembly Instruction Manual Download: http://www.uswaterrockets.com/shared/Se ... y_V101.pdf

ServoChron(tm) Programming Instruction Manual Download: http://www.uswaterrockets.com/shared/Se ... g_V100.pdf

ServoChron(tm) Operating Instruction Manual Download: http://www.uswaterrockets.com/shared/Se ... g_V100.pdf


Comments and Suggestions:
If you have any comments or suggestions for added features or wish to report any software bugs, please add them to this thread. We check this forum regularly and will be monitoring this topic for user feedback. In the event of any firmware updates, we will be posting them here and you can download the update and load it into your ServoChron(tm) using the method described in the programming manual.

[BBruce]

This is wonderful! I have been looking for someone to make something like this forever.
My question is about the battery. Can I use regular alkaline batteries like AAA batteries with this? I have piles of rechargable AAAs already and would like to use them. Thank you for this cool project!

[Nickholas]

Can I use a 5V servo with this? I have many around the shop.

Thank you guys for sharing your design.

[tcarnahan]

I purchased one of these TI LaunchPad boards about two months ago thinking this would be a great way to create a "flight timer' to control my servo using PWM. I just didn't get around to figuring it out ... thanks for running this "into the end zone"!

By the way, the MSP430 is very low power. Have you considered using a Capacitor to hold a charge, charge it before launch, then leave the battery behind to save weight?

[U.S. Water Rockets2]

This is wonderful! I have been looking for someone to make something like this forever.
My question is about the battery. Can I use regular alkaline batteries like AAA batteries with this? I have piles of rechargable AAAs already and would like to use them. Thank you for this cool project!

You can use 1.5v cells but you would have to connect them in series to step the voltage up but be sure not to exceed the specs of the regulator on the MSP430 LaunchPad. The design is able to function from 3.8V to 10V, so any combination of batteries you can come up with that generates a voltage in that range is fine.

You should be fine down to around 3.6V but the regulator is below the dropout voltage and will not be stable but it should still work. Above 10V is stressing the regulator part and it may burn out. A 9V battery should be a nice compromise if you don't like LiPo.

Here is a link to a 9V battery connector you can use:
http://search.digikey.com/scripts/DkSea ... me=BS6I-ND

Here is a 3-cell AAA holder:
http://search.digikey.com/scripts/DkSea ... e=2480K-ND

Here is a 4-cell AAA holder:
http://search.digikey.com/scripts/DkSea ... H24AAAW-ND

P.S. Hopefully, you are not recharging alkaline batteries... did you really mean to say that?

[U.S. Water Rockets2]

Can I use a 5V servo with this? I have many around the shop.

Thank you guys for sharing your design.

Many 5V servos will work fine at the 3.6V power this design supplies but they don't swing as fast at lower voltages. Some 5V servos we tested did not work at all at 3.6V. You should test what you have and see if it works at the 3.6V level.

However, almost all 5V servos will take a control signal as low as 3.0V so the ServoChron(tm) should be able to supply the control and the battery would supply power directly to the 5V servo. If you use one of the AAA battery holders we noted above to get a battery voltage of 4.5 (3-cell) to 6V (4-cell), you can tie the (+) Red and (-) Black of the 5V servo to the battery pack (+) Red and (-) Black leads for power. Then, all you need to do is connect the gray control wire to the pad on the MSP430 LaunchPad for the control signal.

Since the MSP430 microcontroller provides the control signal at 3.6V, it is plenty to satisfy the 3.0V required bu the 5V servo.

We happen to like the single cell servos because the single Lipo weighs 3.8g and the servo weighs 3.8g with wiring and horn connected. We like the weight savings.

[U.S. Water Rockets2]

I purchased one of these TI LaunchPad boards about two months ago thinking this would be a great way to create a "flight timer' to control my servo using PWM. I just didn't get around to figuring it out ... thanks for running this "into the end zone"!

By the way, the MSP430 is very low power. Have you considered using a Capacitor to hold a charge, charge it before launch, then leave the battery behind to save weight?

We have been designing projects with the LaunchPad for over a year now. We bough several of them and have some other projects that will be of interest to Water Rocket folks that are in various stages of completion. There are tons of things you can do with this board and it's so inexpensive that nobody cares if you break a few of them along the way.

On our USWaterRockets Youtube Channel (http://www.youtube.com/uswaterrockets), we have a MSP430 LaunchPad project to reprogram the flash memory chip inside the MD80 clone and the 808 carkeys keychain spy camera that will disable and completely remove the timestamp/date from the video files.

It's great to hear that we were able to boost your idea with our software. It seems that great minds think alike! The MSP430 LaunchPad is an obvious choice for projects like this. We were amazed that nobody had mentioned they were making a servo timer like this. It's not surprising to hear you had the same thought.

Regarding your question about capacitors, it turns out that the energy density of LiPo batteries is the highest you can get for a low price. You could probably do better with aerogel supercaps, but those cost an awful lot of money and a crash would destroy them for sure. Regular cheap capacitors would easily run the MSP430 for a long time because it is so low power, but the issue is the servo. The servo can draw a lot of power and would quickly drain the cap. In short, the MSP430 is low power, but the servo is not. The most cost efficient way to power the servo is a LiPo.

The MSP430 is so low power that it can run from a small photo sensor practically forever, and there are piezo transducers which could power it from the vibrations of a launch.

Thanks for the feedback!

[PepsiMax]

US Waterrockets, I saw your video and wanted to say you have really put together a great little product. I am really impressed by the work you put into what is obviously a llabor of love. I have ordered the parts to build 4 systems and will use it to teach a bit of electronics to my grandsons. Keep up the good work and thank you for contributing the plans for this design!

[tcarnahan]

... it turns out that the energy density of LiPo batteries is the highest you can get for a low price.

I need to spend more time reading your documentation ... sorry ... been a little busy lately, which is the reason I didn't get very far on using the MSP430 for a servo controller.

Question: LiPo battery ... "Lithium ??? what ???" ... that acronym doesn't ring a bell. Also, can you recommend a source for the batteries (on the web?), or are they available locally in the U.S.? Thanks!

[U.S. Water Rockets]

US Waterrockets, I saw your video and wanted to say you have really put together a great little product. I am really impressed by the work you put into what is obviously a llabor of love. I have ordered the parts to build 4 systems and will use it to teach a bit of electronics to my grandsons. Keep up the good work and thank you for contributing the plans for this design!

Thanks for the great feedback. That is highly motivating. We are excited to finish the other MSP430 projects we have ongoing.

This is a great platform because you can keep using the same board for all of these projects.

Keep watching for more firmware projects!

[U.S. Water Rockets]

... it turns out that the energy density of LiPo batteries is the highest you can get for a low price.

I need to spend more time reading your documentation ... sorry ... been a little busy lately, which is the reason I didn't get very far on using the MSP430 for a servo controller.

Question: LiPo battery ... "Lithium ??? what ???" ... that acronym doesn't ring a bell. Also, can you recommend a source for the batteries (on the web?), or are they available locally in the U.S.? Thanks!

No problem. Take your time with the docs.

As for LiPo, it stands for Lithium Polymer Battery. There are different formulations of them. Just be aware these are the type that are used in electric flyer planes, laptops, cellphones, and electric cars. Not the cheapest, but the highest density and most bang-for-the-buck.

[U.S. Water Rockets1]

The intent of this post is to correct a number of myths and misleading statements being made regarding certain deployment controllers:

Myth: The launchpad timer is certainly a cost effective option to go with if you like to tinker with micro controllers.
Fact: the ServoChron(tm) was designed for everyone to use and the instructions were written so that people with no electronics experience would be able to follow them. Persons with no interest in microcontrollers are not excluded. An interest in building water rockets is all anyone needs!

Myth: Texas Instruments actually make a loss on these development boards, but for them it's worth the few lost dollars if they can get a new developer to learn about their controller family.
Fact: TI is not selling their LaunchPad at a loss. They make a majority of the parts used in the design and can afford to sell at such a low price. But what does their margin have to do with the question from the OP? Paying less for something is considered a GOOD thing by most people.

Myth: The cost of the launchpad timer is actually closer to $10 by the time you add a power switch, push button, battery connector and servo motor connector.
Fact: The ServoChron(tm) cost is closer to $4.30 than it is to $10, even with those optional accessories. The assembly manual has a parts list that includes these options, and the total price for a "Loaded" system would be closer to $6.00 fully optioned. 6 is closer to 4.3 than it is to 10. Unless you have some newfangled "fuzzy math".

Myth: The most expensive component on the board is the built-in acceleration switch which costs close to $8.
Fact: http://uk.farnell.com/assemtech/asls2/s ... dp/4229058 which at the current exchange rate is 4.3699 Australian dollars. Only after applying your "fuzzy math" is this "close to" $8.

Myth: The servo timer II comes fully assembled & tested and is ready to use out of the box. There is no need to download and install any software, and no soldering is required. Just plug in a servo and battery and you are good to go. For people who don't own a soldering iron or are not comfortable with having to do their own assembly, and doing firmware updates then the STII is a good alternative.
Fact: People who build and fly water rockets are offended by comments such as the above that imply that somehow they are not good with their hands or that they are afraid to make something with their own two hands. It's mind boggling to consider that someone who can build a water rocket and launcher is too lazy or frightened or unskilled to solder 7 connections to a board. The suggestion that downloading firmware is a huge burden is also intellectually dishonest as well, since most people have come to expect that electronics devices should come with the ability to update them to improve them and add features.

Myth: While it is possible to add extra components to the launchpad to match some of the features of the STII, you may have to order them, and not only pay for the components but also their shipping costs. For example purchasing anything outside the US from digikey incurs a flat $30 delivery fee.
Fact: There companies all over the world that sell electronics components. To try and criticize the price of an item by finding the worst retailer and quoting their price is just making straw man arguments.

Myth: If you are really pressed for space for example in a narrow body rocket then the STII has a footprint of around 1/3 the size of the launchpad, and weighs less than half the weight.
Fact: If you read the documentation for the MSP430 Launchpad, you would see they printed a "dotted line" on the board and included a connector you can cut the board apart and install so the programming portion of the board can be separated from the application portion. People interested in weight savings or concerned about size have this option.

Myth: That's why we always make the circuit diagrams, PCB layouts and code available for free for those that want to make the timers themselves.
Fact: The code only seems to become available after the products are no longer profitable.

This concludes our corrections. We thought that after 2 weeks without being attacked that people were willing to let people make up their own minds, but the peace was short lived. Hopefully, future discussions will be more discussion and less TV commercial.

[milly]

Hello

I want to thank you guys for making this servo timer available as a free download. This is just what my son was lookig for.

Milly

[tcarnahan]

As for LiPo, it stands for Lithium Polymer Battery. There are different formulations of them. Just be aware these are the type that are used in electric flyer planes, laptops, cellphones, and electric cars. Not the cheapest, but the highest density and most bang-for-the-buck.

After reading your comments about LIPO batteries, I rushed out and bought several on the web. When they arrived, I discovered the error of my ways ... "How does one charge these things?" and "How do you connect them to other electronic components?"

The LIPO battery I bought was: http://www.hobbyking.com/hobbyking/stor ... oduct=7566

Any suggestions?

[U.S. Water Rockets2]

When you buy those batteries from Hobbyking, they usually have a link to the recommended charger for them. In this case there is no link, but you could probably just ask their customer service, they are probably pretty helpful.

You could also look on ebay for a 3.7V LiPo charger. Just make sure to get the right voltage and current rating for the mA/hr of your battery.

Another option is to build a simple charging circuit. If you tinker with electronics you could look up LiPo charger IC's on Digikey and put together a breadboard using the reference designs.

The really simple method is to repurpose some other device that has the charger built in. For example:

To recharge our ServoChron(tm) batteries (The little Turnigy ones in the recommended parts list) we made a charger out of an MD80 clone camera. We just replaced the battery inside with a lead for the LiPo and plug it into the USB port of a PC and it charges them and didn't cost anything. We made a second charger out of a bluetooth headset the same way. It plugs into a charger stand that works off AC line or a car +12VDC port.

The batteries you have will need to have wire soldered to the tabs to connect to a board or device. If you want to charge them you would need to use alligator clips or something to connect to them.

Always be careul with these batteries. They are very powerful and if you short circuit them the wiring gets very HOT. They should be handled with care as the material inside is pretty nasty and you should not leave them charging unattended.

The power LiPo provides is so much more than other batteries you will never go back!