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Portela

Confusing signal from the receiver futaba 127df

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I created a circuit that connects to the PIC channel 5 or 6. Tthis circuit receives the signal that channel and increases a counter. My problem occurs when the receiver is turned on the radio before, it makes the circuit increase unduly because of a false pulse. I need to find a way when the receiver is turned on before the radio, not increase the meter (does not have this false jump). I need to treat this disturbing signal.

Jean Portela

Brazil - SP

17/10/2008

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Cannot you add a short power up delay before your counter starts?

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Hi, Jean

The safer way would be to verify the signal length : must be 800 to 2200 µs.

The safest would be to verify if this filtered signal keeps the same value for, say a second or two.

You'd be sure this is a valid signal ( supposing another transmitter on the same channel isn't turned ON !!! )

When using those signals for commutating devices, I read the pulse 4 to 10 times to be steady as a value before switching on ...

one value outside the "gap" resets the counter ...

5 to 11 "outside" lead to the failsafe stubb of the program ...

Alain

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Cannot you add a short power up delay before your counter starts?

Unfortunately I can not put a delay.

What I would do is put something mechanical to interpret and defeat this false signal.

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Hi, Jean

The safer way would be to verify the signal length : must be 800 to 2200 µs.

The safest would be to verify if this filtered signal keeps the same value for, say a second or two.

You'd be sure this is a valid signal ( supposing another transmitter on the same channel isn't turned ON !!! )

When using those signals for commutating devices, I read the pulse 4 to 10 times to be steady as a value before switching on ...

one value outside the "gap" resets the counter ...

5 to 11 "outside" lead to the failsafe stubb of the program ...

Alain

You'd be sure this is a valid signal ( supposing another transmitter on the same channel isn't turned ON !!! )

I can measure the time of false pulse on futaba 127df and if it will happen, not increase the meter. More if I use another receiver from other technology as

R617FS is that the false pulse is the same.

What with the apparatus to measure the pulse false?

Jean Portela

Brazil

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With every R/C system on the market, the valid pulse range is 800-2200us. So it's no problem if you change receiver. Servos have to work across all brands after all.

However your post makes me wonder what you are actually doing with your PIC. What's the goal of the project? Are you just counting how many pulses the receiver gives, regardless of the stick position? Have you read about what a servo pulse looks like?

Edited by Kilrah

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I can measure the time of false pulse on futaba 127df and if it will happen, not increase the meter.

Hi, Jean

No, you can't : these false pulses can have any valid value in the 800 - 2200 µs range ... I observed it on the pulsemeter I built these days ...

Th only "marker" of these false pulses is the not-steady duration.

BTW this leads mes to ask you what you want to do ... as a project. ( Could be i.e. a "multi switch" device ... ).

Knowing what you want to do will lead us to find how to prevent those false pulses ...

Alain

post-1105-1224407337_thumb.jpg

Edited by Acetronics

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You'd be sure this is a valid signal ( supposing another transmitter on the same channel isn't turned ON !!! )

I can measure the time of false pulse on futaba 127df and if it will happen, not increase the meter. More if I use another receiver from other technology as

R617FS is that the false pulse is the same.

What with the apparatus to measure the pulse false?

Jean Portela

Brazil

Friends,

I created a rocket launcher in which call for "LM" to my Tucano aircraft. I did the whole circuit using PIC 16F877. This circuit can fire up to 8 sparks that trigger the rockets. I have many care about safety such as using rockets with explosives, battery exclusive to this circuit and to fire a spark is needed up and down the keys of the radio channel 5 or 6 for two consecutive times. However I found a false signal problem, that is, assuming that someone reverse the order of linking the system Model aircraft (Wrong: Turn on the LM, connect the receiver, turn on the radio) This is a spark shooting wrong.

I thought it was possible that sh*t false, he was always a constant, could program the PIC to reject them. Not discarto another circuit to help deal with this sign.

Edited by Portela

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With every R/C system on the market, the valid pulse range is 800-2200us. So it's no problem if you change receiver. Servos have to work across all brands after all.

However your post makes me wonder what you are actually doing with your PIC. What's the goal of the project? Are you just counting how many pulses the receiver gives, regardless of the stick position? Have you read about what a servo pulse looks like?

Friends,

I created a rocket launcher in which call for "LM" to my Tucano aircraft. I did the whole circuit using PIC 16F877. This circuit can fire up to 8 sparks that trigger the rockets. I have many care about safety such as using rockets with explosives, battery exclusive to this circuit and to fire a spark is needed up and down the keys of the radio channel 5 or 6 for two consecutive times. However I found a false signal problem, that is, assuming that someone reverse the order of linking the system Model aircraft (Wrong: Turn on the LM, connect the receiver, turn on the radio) This is a spark shooting wrong.

I thought it was possible that sh*t false, he was always a constant, could program the PIC to reject them. Not discarto another circuit to help deal with this sign.

Edited by Portela

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With every R/C system on the market, the valid pulse range is 800-2200us. So it's no problem if you change receiver. Servos have to work across all brands after all.

However your post makes me wonder what you are actually doing with your PIC. What's the goal of the project? Are you just counting how many pulses the receiver gives, regardless of the stick position? Have you read about what a servo pulse looks like?

Friends,

I created a rocket launcher in which call for "LM" to my Tucano aircraft. I did the whole circuit using PIC 16F877. This circuit can fire up to 8 sparks that trigger the rockets. I have many care about safety such as using rockets with explosives, battery exclusive to this circuit and to fire a spark is needed up and down the keys of the radio channel 5 or 6 for two consecutive times. However I found a false signal problem, that is, assuming that someone reverse the order of linking the system Model aircraft (Wrong: Turn on the LM, connect the receiver, turn on the radio) This is a spark shooting wrong.

I thought it was possible that sh*t false, he was always a constant, could program the PIC to reject them. Not discarto another circuit to help deal with this sign.

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Can you tell us how you are reading the receiver's signal in your program?

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Hi, Jean

I made a rocket Launcher for my F14 GreatPlanes, 15 years ago, with 4000 CMOS Logic.

I used then 2 channels, 1 locking channel, and 1 Channel for fire ( rockets are launched " serially" ). Plus to that, I use a PCM receiver...

Of course, the two channel signals must be both Ok to allow firing.

Never got any misfunction that way.

You also could test for a very narrow "good" signal variation AND sampling 8 to 10 incoming signals ... but that implies "auto learning" programming of the switch points. Easy to realize ( I do it for all my devices, now ... ).

Alain

Edited by Acetronics

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Hi, Jean

I made a rocket Launcher for my F14 GreatPlanes, 15 years ago, with 4000 CMOS Logic.

I used then 2 channels, 1 locking channel, and 1 Channel for fire ( rockets are launched " serially" ). Plus to that, I use a PCM receiver...

Of course, the two channel signals must be both Ok to allow firing.

Never got any misfunction that way.

You also could test for a very narrow "good" signal variation AND sampling 8 to 10 incoming signals ... but that implies "auto learning" programming of the switch points. Easy to realize ( I do it for all my devices, now ... ).

Alain

Alain legal,

Good to know that other colleagues have done that too.

"I did not understand well the case of two channels." Note: I have only 1 channel free for use on this project.

Alain, my translation to his post was complicated and that I understand you have projects with some logic already made.

Please ask more details!

If they want to write my email, is this:

jeancarloportela-AT-gmail.com

There can exchange files of the program circuits, photos and more.

Thanks to everyone!

Jean Portela

Brazil - Sao Paulo

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Can you tell us how you are reading the receiver's signal in your program?

Dear all,

I'm simply comparing the "duty cycle" of the pulse which can vary from 1 to 2ms in high level with a 20ms repetition rate (period).

The strategy I'm using is to reset a counter in the rising edge and read it in the falling edge of the pulse. The counter dimension is such that it doesn't overflow for much more than 2ms. There is a threshold value and enough resolution in the counter to indirectly but in a precise way measure this time. I adopted half of the up time (1.5ms) as a threshold and there is an histeresys to debounce the signal.

The problem is that when the receiver is left ON and the radio is switched OFF, the receiver output is stable in a certain duty value but this value is different and unpredictable for every time the radio is turned OFF.

Do someone know how to ensure the receiver to be keep in a known duty (say, 1ms) when the radio is off or out of reach?

Jean Portela

Brazil-SP

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OK, everything seems correct.

So, if you say the receiver will give an unpredictable but stable pulse, you're pretty much out of luck. The pulse length with radio off will depend on RF noise that is present, so one can't really set it.

What I would do is use an "arming sequence". When the system is powered ON, the user first needs to follow a sequence (for example, switch ON for more than 1 second, then OFF for more than one second), and then only the system will activate and allow firing to be triggered. I'd also filter the input quite a bit so that a consistent input has to be fed for a certain time to trigger firing, so that an RX glitch wouldn't cause accidental firing.

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OK, everything seems correct.

So, if you say the receiver will give an unpredictable but stable pulse, you're pretty much out of luck. The pulse length with radio off will depend on RF noise that is present, so one can't really set it.

What I would do is use an "arming sequence". When the system is powered ON, the user first needs to follow a sequence (for example, switch ON for more than 1 second, then OFF for more than one second), and then only the system will activate and allow firing to be triggered. I'd also filter the input quite a bit so that a consistent input has to be fed for a certain time to trigger firing, so that an RX glitch wouldn't cause accidental firing.

Kilrah,

Have we in this circuit, that is, by pressing a key channel of 5 or 6 to "ON" there is a time of 2 seconds to arm. Moving the key to the channel to "Off", is then fired the rocket.

We must now create a way that prevents the release if the model destraído leave its equipment on the plane. Or connect the equipment in a sequence such as wrong turn on the circuit LM, connect the receiver and finally the radio.

It is worth mentioning that the circuit LM can shoot up to 20 rockets, and if you shoot only "5" and put the plane, he irar record in permanent memory the last door that was triggered "5". When connecting the circuit he prepares the door "6" and if it triggers a pulse it wrong to 6. That is what we want to avoid, but it is very difficult.

Let's think!

Regards, Jean Portela - Brazil

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