Forums

Need some help making an R/C interface

Started by smitty505000 September 6, 2005
Hey all,

I am looking for some sugestions on how to make an R/C interface
with a PIC 16f628. I want 5 or 6 outputs that will be able to set off
rocket igniters. I will be using one momentary switch on my Futaba
transmitter and want to be able to pull the switch once and set off
the first igniter, then pull it again and set off the second, and so
forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back to off
and just keep cycling by one as I pull the switch. Each output will
also have an LED to indicate which is active. The igniters are a dead
short so the outputs have to be able to handle it and I dont really
want to use relays because they are heavy.

Any help would be greatly appreciated!
Thanks
Smitty



Hi Smitty,

6 rockets? That should be impressive!

To get around using relays or high current drivers, you might think about using
a large cap and a SCR-like trigger circuit. These are/were used in electronic
flash, and what we used to call BC flash (battery/cap).

What type of channel signal does a momentary switch closure produce? A FULL-ON
servo value, or something else? You can of course "watch" the received signal,
and decode the channels you want. If you have a single "PB" signal from the
receiver, then your PIC can simply count the "PB" signals from the single
receiver line, and determine which SCR to fire.

USUAL DISCLAIMERS, Implement at your own risk! Be Save and all that!

Alan KM6VV smitty505000 wrote:

> Hey all,
>
> I am looking for some sugestions on how to make an R/C interface
> with a PIC 16f628. I want 5 or 6 outputs that will be able to set off
> rocket igniters. I will be using one momentary switch on my Futaba
> transmitter and want to be able to pull the switch once and set off
> the first igniter, then pull it again and set off the second, and so
> forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back to off
> and just keep cycling by one as I pull the switch. Each output will
> also have an LED to indicate which is active. The igniters are a dead
> short so the outputs have to be able to handle it and I dont really
> want to use relays because they are heavy.
>
> Any help would be greatly appreciated!
> Thanks
> Smitty
>


Its fairly simple to make an RC switch so that lights, or a camera can
be operated from the transmitter, normally via CH5 which is often used
for the gear switch, but as this is an on/off switch, your PIC would
have to count the number of times the switch was activated and thus fire
your rockets sequentially.

RC uses a pulse proportional signal for each channel, with each channel
and a sync pulse being sent every 20 mS. These pulses are between 1ms
and 2ms, 1ms being read as off and 2ms as full on, with 1.5ms as centre
stick. So you would need to write the code that detects when the pulse
on CH5 is 2ms long, then watch for the signal to be 1ms long before
adding the count to a counter.

To actually switch the voltage / current to ignite the fuses, a simple
FET could be used, something like an IRLZ14 would be fine, but I'm not
sure if placing an igniter across them would also blow them or if they
could take having the output shorted. I s'pose it depends on how long
it takes before the igniter burns through and goes open circuit.

There are two ways of building the firing cct, one would be to have X
number of FETs connected to X number of pins on the PIC which are
sequentially made to go high, or feed the output of a smaller PIC to a
4017 decade counter. I use a 12F765 to switch landing lights on and off
on one of my helicopters, this could be used with a 4017 counter to
provide 10 rocket launches.

Hope these suggestions help

Malcolm

Disclaimer: I take no responsibility what so ever for any damage to
you, your RC equipment or what ever you blow up with your rockets etc..
etc.. You follow / use these suggestions entirely at your own risk.

smitty505000 wrote:

> Hey all,
>
> I am looking for some sugestions on how to make an R/C interface
> with a PIC 16f628. I want 5 or 6 outputs that will be able to set off
> rocket igniters. I will be using one momentary switch on my Futaba
> transmitter and want to be able to pull the switch once and set off
> the first igniter, then pull it again and set off the second, and so
> forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back to off
> and just keep cycling by one as I pull the switch. Each output will
> also have an LED to indicate which is active. The igniters are a dead
> short so the outputs have to be able to handle it and I dont really
> want to use relays because they are heavy.
>
> Any help would be greatly appreciated!
> Thanks
> Smitty > to unsubscribe, go to http://www.yahoogroups.com and follow the
> instructions >
> >. >
>



--- In piclist@picl..., "smitty505000" <smitty505000@y...> wrote:
> Hey all,
>
> I am looking for some sugestions on how to make an R/C interface
> with a PIC 16f628. I want 5 or 6 outputs that will be able to set off
> rocket igniters. I will be using one momentary switch on my Futaba
> transmitter and want to be able to pull the switch once and set off
> the first igniter, then pull it again and set off the second, and so
> forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back to off
> and just keep cycling by one as I pull the switch. Each output will
> also have an LED to indicate which is active. The igniters are a dead
> short so the outputs have to be able to handle it and I dont really
> want to use relays because they are heavy.
>
> Any help would be greatly appreciated!
> Thanks
> Smitty

The simplest solution that I can think of would be to use the full
travel of the servo to drive a rotary switch via a ratchet.

You might find something that is avilable pre-built. I did a quick
search on google and found a simple ratchet built using leggo at

http://mapageweb.umontreal.ca/cousined/lego/3-Physics/Ratchets/lego_ratchet.html

You might find something better suited to your needs if you spend a
while searching yourself.

Of course you would use a servo here instead of the 628.

Another possible solution might be to use a data RF link and actually
have seperate push buttons for each of the igniters. Have a look at

http://www.rfsolutions.co.uk/acatalog/index.html

for the type of RF data modules that are available (and price). The
advantage here is that the receivers can be very cheap and you can
actually add safety to your comms protocol.

Regards
Sergio Masci

http://www.xcprod.com/titan/XCSB - optimising PIC compiler
FREE for personal non-commercial use

.


I like the decade counter! I already have circuit for an R/C on off
switch and can use the output of that to drive the decade counter. I
think I can put TIP120's on the decade counter outputs to fire the
igniters. The decade counter goes from 0-9 so I can put a green led
on pin 0 to show safe or off then red leds on the rest that will
fire the igniters. Also can incorporate an arming switch on the
ground leg of the igniters for safety reasons of course. This should
work huh?

Smitty --- In piclist@picl..., Malcolm <malcolm.crabbe@n...> wrote:
> Its fairly simple to make an RC switch so that lights, or a camera
can
> be operated from the transmitter, normally via CH5 which is often
used
> for the gear switch, but as this is an on/off switch, your PIC
would
> have to count the number of times the switch was activated and
thus fire
> your rockets sequentially.
>
> RC uses a pulse proportional signal for each channel, with each
channel
> and a sync pulse being sent every 20 mS. These pulses are between
1ms
> and 2ms, 1ms being read as off and 2ms as full on, with 1.5ms as
centre
> stick. So you would need to write the code that detects when the
pulse
> on CH5 is 2ms long, then watch for the signal to be 1ms long
before
> adding the count to a counter.
>
> To actually switch the voltage / current to ignite the fuses, a
simple
> FET could be used, something like an IRLZ14 would be fine, but
I'm not
> sure if placing an igniter across them would also blow them or if
they
> could take having the output shorted. I s'pose it depends on how
long
> it takes before the igniter burns through and goes open circuit.
>
> There are two ways of building the firing cct, one would be to
have X
> number of FETs connected to X number of pins on the PIC which are
> sequentially made to go high, or feed the output of a smaller PIC
to a
> 4017 decade counter. I use a 12F765 to switch landing lights on
and off
> on one of my helicopters, this could be used with a 4017 counter
to
> provide 10 rocket launches.
>
> Hope these suggestions help
>
> Malcolm
>
> Disclaimer: I take no responsibility what so ever for any damage
to
> you, your RC equipment or what ever you blow up with your rockets
etc..
> etc.. You follow / use these suggestions entirely at your own
risk.
>
> smitty505000 wrote:
>
> > Hey all,
> >
> > I am looking for some sugestions on how to make an R/C
interface
> > with a PIC 16f628. I want 5 or 6 outputs that will be able to
set off
> > rocket igniters. I will be using one momentary switch on my
Futaba
> > transmitter and want to be able to pull the switch once and set
off
> > the first igniter, then pull it again and set off the second,
and so
> > forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back
to off
> > and just keep cycling by one as I pull the switch. Each output
will
> > also have an LED to indicate which is active. The igniters are a
dead
> > short so the outputs have to be able to handle it and I dont
really
> > want to use relays because they are heavy.
> >
> > Any help would be greatly appreciated!
> > Thanks
> > Smitty
> >
> >
> >
> >
> >
> > to unsubscribe, go to http://www.yahoogroups.com and follow the
> > instructions
> >
> >
> > -----------------------------
-------
> > >.
> >
> >
> > -----------------------------
-------
> >



Thanks for your help! I think I found a solution, see my other post.

Thanks again!!

Smitty

--- In piclist@picl..., KM6VV <KM6VV@a...> wrote:
> Hi Smitty,
>
> 6 rockets? That should be impressive!
>
> To get around using relays or high current drivers, you might
think about using
> a large cap and a SCR-like trigger circuit. These are/were used
in electronic
> flash, and what we used to call BC flash (battery/cap).
>
> What type of channel signal does a momentary switch closure
produce? A FULL-ON
> servo value, or something else? You can of course "watch" the
received signal,
> and decode the channels you want. If you have a single "PB"
signal from the
> receiver, then your PIC can simply count the "PB" signals from the
single
> receiver line, and determine which SCR to fire.
>
> USUAL DISCLAIMERS, Implement at your own risk! Be Save and all
that!
>
> Alan KM6VV > smitty505000 wrote:
>
> > Hey all,
> >
> > I am looking for some sugestions on how to make an R/C
interface
> > with a PIC 16f628. I want 5 or 6 outputs that will be able to
set off
> > rocket igniters. I will be using one momentary switch on my
Futaba
> > transmitter and want to be able to pull the switch once and set
off
> > the first igniter, then pull it again and set off the second,
and so
> > forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back
to off
> > and just keep cycling by one as I pull the switch. Each output
will
> > also have an LED to indicate which is active. The igniters are a
dead
> > short so the outputs have to be able to handle it and I dont
really
> > want to use relays because they are heavy.
> >
> > Any help would be greatly appreciated!
> > Thanks
> > Smitty
> >


Hi Smitty
I have done this already (using 16f84 or 16f628) for rocket
launchers from model MTB - I had an enquiry to do so from a person
who visited my web site - He never actually came back once I had
done the programming !! grrr
I was careful to build in some kind of deliberate control sequence
from the TX operator to reduce the possiblity that interference
would set off the rockets in someone's face. Up to 8 ignitions were
then triggered sequentially on TX requests.
Visit my website for further details & circuit - build & fire at you
own risk !!
Bazling
http://www.kleefeld.freeserve.co.uk/model/barry/pic01/rc_swit.htm#Swi
tch02

--- In piclist@picl..., "smitty505000" <smitty505000@y...>
wrote:
> Hey all,
>
> I am looking for some sugestions on how to make an R/C interface
> with a PIC 16f628. I want 5 or 6 outputs that will be able to set
off
> rocket igniters. I will be using one momentary switch on my Futaba
> transmitter and want to be able to pull the switch once and set
off
> the first igniter, then pull it again and set off the second, and
so
> forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back to
off
> and just keep cycling by one as I pull the switch. Each output
will
> also have an LED to indicate which is active. The igniters are a
dead
> short so the outputs have to be able to handle it and I dont
really
> want to use relays because they are heavy.
>
> Any help would be greatly appreciated!
> Thanks
> Smitty


If you want the basic RC switch, you can download the hex and schematic
from the download page on my RC website http://www.rc-electronics.net/
All you would need to do is add the 4017 and FETs... uhm you got me
thinking.. my son has an estee rocket somewhere, and I'm sure we had a
pack of three motors laying around :-) I've also got a few FETs etc..
just might have a play, you could fit this thing on a small board the
size of fag packet !

let us know how you get on

Malcolm

smitty505000 wrote:

> I like the decade counter! I already have circuit for an R/C on off
> switch and can use the output of that to drive the decade counter. I
> think I can put TIP120's on the decade counter outputs to fire the
> igniters. The decade counter goes from 0-9 so I can put a green led
> on pin 0 to show safe or off then red leds on the rest that will
> fire the igniters. Also can incorporate an arming switch on the
> ground leg of the igniters for safety reasons of course. This should
> work huh?
>
> Smitty > --- In piclist@picl..., Malcolm <malcolm.crabbe@n...> wrote:
> > Its fairly simple to make an RC switch so that lights, or a camera
> can
> > be operated from the transmitter, normally via CH5 which is often
> used
> > for the gear switch, but as this is an on/off switch, your PIC
> would
> > have to count the number of times the switch was activated and
> thus fire
> > your rockets sequentially.
> >
> > RC uses a pulse proportional signal for each channel, with each
> channel
> > and a sync pulse being sent every 20 mS. These pulses are between
> 1ms
> > and 2ms, 1ms being read as off and 2ms as full on, with 1.5ms as
> centre
> > stick. So you would need to write the code that detects when the
> pulse
> > on CH5 is 2ms long, then watch for the signal to be 1ms long
> before
> > adding the count to a counter.
> >
> > To actually switch the voltage / current to ignite the fuses, a
> simple
> > FET could be used, something like an IRLZ14 would be fine, but
> I'm not
> > sure if placing an igniter across them would also blow them or if
> they
> > could take having the output shorted. I s'pose it depends on how
> long
> > it takes before the igniter burns through and goes open circuit.
> >
> > There are two ways of building the firing cct, one would be to
> have X
> > number of FETs connected to X number of pins on the PIC which are
> > sequentially made to go high, or feed the output of a smaller PIC
> to a
> > 4017 decade counter. I use a 12F765 to switch landing lights on
> and off
> > on one of my helicopters, this could be used with a 4017 counter
> to
> > provide 10 rocket launches.
> >
> > Hope these suggestions help
> >
> > Malcolm
> >
> > Disclaimer: I take no responsibility what so ever for any damage
> to
> > you, your RC equipment or what ever you blow up with your rockets
> etc..
> > etc.. You follow / use these suggestions entirely at your own
> risk.
> >
> > smitty505000 wrote:
> >
> > > Hey all,
> > >
> > > I am looking for some sugestions on how to make an R/C
> interface
> > > with a PIC 16f628. I want 5 or 6 outputs that will be able to
> set off
> > > rocket igniters. I will be using one momentary switch on my
> Futaba
> > > transmitter and want to be able to pull the switch once and set
> off
> > > the first igniter, then pull it again and set off the second,
> and so
> > > forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back
> to off
> > > and just keep cycling by one as I pull the switch. Each output
> will
> > > also have an LED to indicate which is active. The igniters are a
> dead
> > > short so the outputs have to be able to handle it and I dont
> really
> > > want to use relays because they are heavy.
> > >
> > > Any help would be greatly appreciated!
> > > Thanks
> > > Smitty
> > >
> > >
> > >
> > >
> > >
> > > to unsubscribe, go to http://www.yahoogroups.com and follow the
> > > instructions
> > >
> > >
> > > -----------------------------
> -------
> > > >.
> > >
> > >
> > > -----------------------------
> -------
> > > to unsubscribe, go to http://www.yahoogroups.com and follow the
> instructions >
> >. >
>



WOW, very nice! I already have most of those components also. Just
need some mosfets. The only problem is I dont know where to start
programing. I have picbasic pro and a programer but little
knowledge. I have done a few simple programs for flashing lights on
my R2 unit but thats it.

Smitty

--- In piclist@picl..., "bazling" <Barry@k...> wrote:
> Hi Smitty
> I have done this already (using 16f84 or 16f628) for rocket
> launchers from model MTB - I had an enquiry to do so from a person
> who visited my web site - He never actually came back once I had
> done the programming !! grrr
> I was careful to build in some kind of deliberate control sequence
> from the TX operator to reduce the possiblity that interference
> would set off the rockets in someone's face. Up to 8 ignitions
were
> then triggered sequentially on TX requests.
> Visit my website for further details & circuit - build & fire at
you
> own risk !!
> Bazling
>
http://www.kleefeld.freeserve.co.uk/model/barry/pic01/rc_swit.htm#Swi
> tch02
>
> --- In piclist@picl..., "smitty505000" <smitty505000@y...>
> wrote:
> > Hey all,
> >
> > I am looking for some sugestions on how to make an R/C
interface
> > with a PIC 16f628. I want 5 or 6 outputs that will be able to
set
> off
> > rocket igniters. I will be using one momentary switch on my
Futaba
> > transmitter and want to be able to pull the switch once and set
> off
> > the first igniter, then pull it again and set off the second,
and
> so
> > forth. So I am thinking it will go like 0ff,1,2,3,4,5 then back
to
> off
> > and just keep cycling by one as I pull the switch. Each output
> will
> > also have an LED to indicate which is active. The igniters are a
> dead
> > short so the outputs have to be able to handle it and I dont
> really
> > want to use relays because they are heavy.
> >
> > Any help would be greatly appreciated!
> > Thanks
> > Smitty



If you want to go ahead, I can supply the pre-programmed PIC for
11.00 including UK postage. I also have MOSFETs at 1.30 each

As you can see from the circuit diag, there are a lot of components
to mount. My pictures of my stripboards give an idea of how to do
it. I have left a number of the repeated trigger circuits off the
circuit diag for the sake of clarity. Tackled slowly & carefully is
the order of the day! The LEDs add to the complexity, but save a
lot of troubleshooting - they can be used to show the circuit is
working before adding the trigger relays or MOSFETs

The problem for a new PIC constructor is: When it doesn't work - Is
it the program or the hardware? So I am suggesting that if you are
new to programming then stick to making the hardware first, then try
& improve on my software (if needed! ) in a known good hardware
environment.

Bazling

--- In piclist@picl..., "smitty505000" <smitty505000@y...>
wrote:
> WOW, very nice! I already have most of those components also. Just
> need some mosfets. The only problem is I dont know where to start
> programing. I have picbasic pro and a programer but little
> knowledge. I have done a few simple programs for flashing lights
on
> my R2 unit but thats it.
>
> Smitty >
>
> --- In piclist@picl..., "bazling" <Barry@k...> wrote:
> > Hi Smitty
> > I have done this already (using 16f84 or 16f628) for rocket
> > launchers from model MTB - I had an enquiry to do so from a
person
> > who visited my web site - He never actually came back once I had
> > done the programming !! grrr
> > I was careful to build in some kind of deliberate control
sequence
> > from the TX operator to reduce the possiblity that interference
> > would set off the rockets in someone's face. Up to 8 ignitions
> were
> > then triggered sequentially on TX requests.
> > Visit my website for further details & circuit - build & fire at
> you
> > own risk !!
> > Bazling
> >
>
http://www.kleefeld.freeserve.co.uk/model/barry/pic01/rc_swit.htm#Swi
> > tch02
> >
> > --- In piclist@picl..., "smitty505000"
<smitty505000@y...>
> > wrote:
> > > Hey all,
> > >
> > > I am looking for some sugestions on how to make an R/C
> interface
> > > with a PIC 16f628. I want 5 or 6 outputs that will be able to
> set
> > off
> > > rocket igniters. I will be using one momentary switch on my
> Futaba
> > > transmitter and want to be able to pull the switch once and
set
> > off
> > > the first igniter, then pull it again and set off the second,
> and
> > so
> > > forth. So I am thinking it will go like 0ff,1,2,3,4,5 then
back
> to
> > off
> > > and just keep cycling by one as I pull the switch. Each output
> > will
> > > also have an LED to indicate which is active. The igniters are
a
> > dead
> > > short so the outputs have to be able to handle it and I dont
> > really
> > > want to use relays because they are heavy.
> > >
> > > Any help would be greatly appreciated!
> > > Thanks
> > > Smitty