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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

ServoChron(tm) Firmware Update (Dual servo control)

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by bugwubber » Wed Jan 16, 2013 12:47 am

Does the switch circuit carry the full voltage? I was kicking around the idea of adding LEDs inline with the switch so I could visually tell from a distance if the switch was in the proper state and tripping during flight. I'm using a pressure switch that will close once the pressure gets above 10-15psi. So I wanted to add an indicator light to confirm the swith moved to the closed position, and that it properly opens after pressure drop.


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by bugwubber » Wed Jan 16, 2013 12:48 am

edit <oops duplicate post>


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by bugwubber » Wed Jan 16, 2013 2:40 am

So the answer to that according to my multimeter is no. 3.4 volts, 93 microamps if I'm reading that correctly.


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by U.S. Water Rockets » Fri Jan 18, 2013 3:53 pm

The switch can operate in either a normally open or normally closed arrangement. The firmware looks at the state of the switch at power up/reset and remembers this as the "waiting for launch" switch position. When launched, the switch opens or closes and causes the state of the input to invert to the opposite value. This is the "Launch Detected" state.

You could connect your LED like this:
pressure_indicator.GIF
This should work (we did not test it yet). The LED will be illuminated because the pressure switch will be closed when pressure is over 15PSI and the launch detect input of the ServoChron will see GND at the input because the pressure switch closure will ground it.

When presssure drops, the switch opens up, breaking the circuit to ground on the lLED, turning it off, and also the aunch detect input, so it will see +3V and detect the launch.

Just be aware that the rocket must have enough pressure in it when you reset the ServoChron so that the switch is closed. Make sure you know the rocket is at a very safe pressure when you are starting the electronics. We normally don't recommend working on a rocket with any pressure in it at all, but your switch operates at a reasonable pressure for a smallish volume like a water rocket. 15PSI of air in 10 liters is a small amount of energy... 15PSI of air in an 10,000 gallon oil tanker is a huge potential energy!

Let us know how your design goes, and be safe!
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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by bugwubber » Fri Jan 25, 2013 7:09 pm

Thanks for the diagram! I suppose once I have done more test cycles I'll be more comfortable with the switch. It is located down in the distorted view portion of the bottle neck so it is difficult to visually confirm it is fully closed. The LED would really help. I've got a 1S 160mah3.7v lipo that will be providing power.

Just wanted to say y'all rock! I down loaded the software, for some reason the FET-PRO install ran into an error whenever I would select the install to include the driver. Got around that by just downloading the drivers directly from TI. Beyond that snag, the ServoChron software installed perfectly and has been bench testing flawlessly with my 5v RC servos! Can't wait for the micro servos to come in. Thanks for the advice, friendly support, and the software!


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by U.S. Water Rockets1 » Sun Jan 27, 2013 12:14 am

bugwubber wrote:Thanks for the diagram! I suppose once I have done more test cycles I'll be more comfortable with the switch. It is located down in the distorted view portion of the bottle neck so it is difficult to visually confirm it is fully closed. The LED would really help. I've got a 1S 160mah3.7v lipo that will be providing power.

Just wanted to say y'all rock! I down loaded the software, for some reason the FET-PRO install ran into an error whenever I would select the install to include the driver. Got around that by just downloading the drivers directly from TI. Beyond that snag, the ServoChron software installed perfectly and has been bench testing flawlessly with my 5v RC servos! Can't wait for the micro servos to come in. Thanks for the advice, friendly support, and the software!
Glad you got the software installed. If we understand correctly, you had an issue with the programmer software?


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by bugwubber » Tue Jan 29, 2013 11:38 pm

U.S. Water Rockets1 wrote:
bugwubber wrote:Thanks for the diagram! I suppose once I have done more test cycles I'll be more comfortable with the switch. It is located down in the distorted view portion of the bottle neck so it is difficult to visually confirm it is fully closed. The LED would really help. I've got a 1S 160mah3.7v lipo that will be providing power.

Just wanted to say y'all rock! I down loaded the software, for some reason the FET-PRO install ran into an error whenever I would select the install to include the driver. Got around that by just downloading the drivers directly from TI. Beyond that snag, the ServoChron software installed perfectly and has been bench testing flawlessly with my 5v RC servos! Can't wait for the micro servos to come in. Thanks for the advice, friendly support, and the software!
Glad you got the software installed. If we understand correctly, you had an issue with the programmer software?
Yes, more with the installer. I could install just the program ok but if I selected the option to install the program and the device drivers, it would error and quit. The 430 came packaged with instrutions for downloading software and driver files from ti.com/launchpad so I tried that first and it worked just fine. After I got the driver installed, everything went perfectly.


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by Tony » Tue Feb 19, 2013 2:42 am

Feb 18, 2013

FET-Pro430 software has been updated. Release 3.1 is available!


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by U.S. Water Rockets » Tue Feb 19, 2013 9:51 pm

Tony wrote:Feb 18, 2013

FET-Pro430 software has been updated. Release 3.1 is available!
That's great news. We will check our links and make sure we are pointing to the correct download.



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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by bugwubber » Fri Feb 22, 2013 12:12 am

Gasp! The price of the 430 launchpad has skyrocketed 14% on ti's site to $5.00! Shipping still included. Apparently they also have a free chip sample program.


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by U.S. Water Rockets1 » Sat Feb 23, 2013 11:11 pm

bugwubber wrote:Gasp! The price of the 430 launchpad has skyrocketed 14% on ti's site to $5.00! Shipping still included. Apparently they also have a free chip sample program.
When did that happen? We just ordered some and they were $4.35


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by bugwubber » Fri Mar 08, 2013 3:22 am

U.S. Water Rockets1 wrote:
bugwubber wrote:Gasp! The price of the 430 launchpad has skyrocketed 14% on ti's site to $5.00! Shipping still included. Apparently they also have a free chip sample program.
When did that happen? We just ordered some and they were $4.35
I don't know but something weird is going on. The TI store is now showing 2-4 week backlog and a price of $9.99.

There's an interesting note on the 43oh.com forum about it.

http://forum.43oh.com/topic/3460-is-it- ... entry30573


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by U.S. Water Rockets1 » Sun Mar 10, 2013 12:05 am

bugwubber wrote:
U.S. Water Rockets1 wrote:
bugwubber wrote:Gasp! The price of the 430 launchpad has skyrocketed 14% on ti's site to $5.00! Shipping still included. Apparently they also have a free chip sample program.
When did that happen? We just ordered some and they were $4.35
I don't know but something weird is going on. The TI store is now showing 2-4 week backlog and a price of $9.99.

There's an interesting note on the 43oh.com forum about it.

http://forum.43oh.com/topic/3460-is-it- ... entry30573
We've been discussing this on Twitter and it turns out that TI has had complaints from their education channels that the TI store was selling the LaunchPad for $4.30 with free shipping and so people would buy their launchpad from the TI store instead of the partner channels. The thinking is apparently that if people could get the Launchpad from TI with free shipping then the partner would lose the sale. The partners were mostly not worried about the loss of the Launchpad sale, but the loss of the additional items people typically order to pad out the purchase to spread out the shipping cost over several items.

In the end, TI decided to raise their price to $9.99 (still free shipping) to get people to purchase through the TI partner sales channels. They are working on a FAQ that explains this in more detail and we were told it would be published soon.

In the end it looks like there still will be sources where you can get it for $4.30, just not through the TI store.

Keep in mind, that TI has a generous sample program, so you may be able to get one for free by asking for a sample. Just don't abuse the service.

We will post more info and vendor list when the info is published.


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by bugwubber » Tue Mar 19, 2013 12:55 am

U.S. Water Rockets wrote:The switch can operate in either a normally open or normally closed arrangement. The firmware looks at the state of the switch at power up/reset and remembers this as the "waiting for launch" switch position. When launched, the switch opens or closes and causes the state of the input to invert to the opposite value. This is the "Launch Detected" state.

You could connect your LED like this:
pressure_indicator.GIF
This should work (we did not test it yet). The LED will be illuminated because the pressure switch will be closed when pressure is over 15PSI and the launch detect input of the ServoChron will see GND at the input because the pressure switch closure will ground it.

When presssure drops, the switch opens up, breaking the circuit to ground on the lLED, turning it off, and also the aunch detect input, so it will see +3V and detect the launch.

Just be aware that the rocket must have enough pressure in it when you reset the ServoChron so that the switch is closed. Make sure you know the rocket is at a very safe pressure when you are starting the electronics. We normally don't recommend working on a rocket with any pressure in it at all, but your switch operates at a reasonable pressure for a smallish volume like a water rocket. 15PSI of air in 10 liters is a small amount of energy... 15PSI of air in an 10,000 gallon oil tanker is a huge potential energy!

Let us know how your design goes, and be safe!
Here's my final electronics and pressure switch assembly. I followed your diagram for adding the LED indicator and it is working perfectly. Below is a video where I am operating the switch manually.

http://www.youtube.com/watch?v=fZC9IRHL238


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Re: ServoChron(tm) Firmware Update (Dual servo control)

Post by U.S. Water Rockets1 » Sat Mar 23, 2013 10:46 pm

bugwubber wrote:
U.S. Water Rockets wrote:The switch can operate in either a normally open or normally closed arrangement. The firmware looks at the state of the switch at power up/reset and remembers this as the "waiting for launch" switch position. When launched, the switch opens or closes and causes the state of the input to invert to the opposite value. This is the "Launch Detected" state.

You could connect your LED like this:
pressure_indicator.GIF
This should work (we did not test it yet). The LED will be illuminated because the pressure switch will be closed when pressure is over 15PSI and the launch detect input of the ServoChron will see GND at the input because the pressure switch closure will ground it.

When presssure drops, the switch opens up, breaking the circuit to ground on the lLED, turning it off, and also the aunch detect input, so it will see +3V and detect the launch.

Just be aware that the rocket must have enough pressure in it when you reset the ServoChron so that the switch is closed. Make sure you know the rocket is at a very safe pressure when you are starting the electronics. We normally don't recommend working on a rocket with any pressure in it at all, but your switch operates at a reasonable pressure for a smallish volume like a water rocket. 15PSI of air in 10 liters is a small amount of energy... 15PSI of air in an 10,000 gallon oil tanker is a huge potential energy!

Let us know how your design goes, and be safe!
Here's my final electronics and pressure switch assembly. I followed your diagram for adding the LED indicator and it is working perfectly. Below is a video where I am operating the switch manually.

http://www.youtube.com/watch?v=fZC9IRHL238

That's really impressive. Nice work! Glad you were able to make use of our idea.


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