multiple RC servos, & DC motor speed control
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Posts: 46,084
I am doing a uav project along the same lines
I first measure the pulse width for that particular channel - calculate and
scale position as as a number 0 to 255 - and then send to a serial servo
controller chip - I am using Scott Edward's ssc
I am only using 5 channels but there is room for 8
richard
Original Message
From: "Nic Nicholson" <nicnicholson@p...>
To: "Basic Stamps" <basicstamps@egroups.com>
Sent: Thursday, July 20, 2000 5:54 PM
Subject: [noparse][[/noparse]basicstamps] multiple RC servos, & DC motor speed control
> I know this subject must have come up many times, but I haven't been able
to
> find a satisfactory solution in any of the archives...
>
> I would like to be able to put the BS2 in between an RC receiver and the
> servos it controls, probably three of them, and also control a DC motor at
> the same time. It's the output part of this that's causing me problems.
>
> My intended solution is to make a circuit which takes 0-5V analog in (from
> the PWM of BS2) and will continue to put out a corresponding RC pulse
until
> the the BS2 next updates the analog voltage--sort of a "fire and forget"
> approach. A possible solution that occurred to me was to use a 20mS
astable
> in conjunction with a votage controlled monostable, but I'm not familiar
> enough with what's out there to know which chips to use...I guess the hard
> part of this for me is the voltage-controlled monostable: 0 to 5V in, 1mS
> to 2 mS output. Anyone know how to implement this? I've not decided on
> multivibrators, I'd just like to be able to control a servo with the PWM
> analog output of the BS2.
>
> The second part of this is to control a DC motor using the same analog-out
> technique. I've been looking at the MC33030 chip. Has anyone tried using
a
> motor tach as the feedback on this chip? Does anyone know any reasons why
> this chip can't be controlled with a 0 to 5V input? (I would, of course,
> scale this up to 0 to Vcc with a transistor to the reference input)
>
> Also, I have a couple of LM18200T's on the shelf, so if anyone knows how
to
> go from BS2 analog-out to PWM. I'd love to know the name of a good chip
> here too.
>
>
> The main type of information I'm looking for here is suggestions of chips
to
> look at...anyone?
>
> Thanks,
>
> Nic
>
>
>
>
>
>
I first measure the pulse width for that particular channel - calculate and
scale position as as a number 0 to 255 - and then send to a serial servo
controller chip - I am using Scott Edward's ssc
I am only using 5 channels but there is room for 8
richard
Original Message
From: "Nic Nicholson" <nicnicholson@p...>
To: "Basic Stamps" <basicstamps@egroups.com>
Sent: Thursday, July 20, 2000 5:54 PM
Subject: [noparse][[/noparse]basicstamps] multiple RC servos, & DC motor speed control
> I know this subject must have come up many times, but I haven't been able
to
> find a satisfactory solution in any of the archives...
>
> I would like to be able to put the BS2 in between an RC receiver and the
> servos it controls, probably three of them, and also control a DC motor at
> the same time. It's the output part of this that's causing me problems.
>
> My intended solution is to make a circuit which takes 0-5V analog in (from
> the PWM of BS2) and will continue to put out a corresponding RC pulse
until
> the the BS2 next updates the analog voltage--sort of a "fire and forget"
> approach. A possible solution that occurred to me was to use a 20mS
astable
> in conjunction with a votage controlled monostable, but I'm not familiar
> enough with what's out there to know which chips to use...I guess the hard
> part of this for me is the voltage-controlled monostable: 0 to 5V in, 1mS
> to 2 mS output. Anyone know how to implement this? I've not decided on
> multivibrators, I'd just like to be able to control a servo with the PWM
> analog output of the BS2.
>
> The second part of this is to control a DC motor using the same analog-out
> technique. I've been looking at the MC33030 chip. Has anyone tried using
a
> motor tach as the feedback on this chip? Does anyone know any reasons why
> this chip can't be controlled with a 0 to 5V input? (I would, of course,
> scale this up to 0 to Vcc with a transistor to the reference input)
>
> Also, I have a couple of LM18200T's on the shelf, so if anyone knows how
to
> go from BS2 analog-out to PWM. I'd love to know the name of a good chip
> here too.
>
>
> The main type of information I'm looking for here is suggestions of chips
to
> look at...anyone?
>
> Thanks,
>
> Nic
>
>
>
>
>
>
Comments
find a satisfactory solution in any of the archives...
I would like to be able to put the BS2 in between an RC receiver and the
servos it controls, probably three of them, and also control a DC motor at
the same time. It's the output part of this that's causing me problems.
My intended solution is to make a circuit which takes 0-5V analog in (from
the PWM of BS2) and will continue to put out a corresponding RC pulse until
the the BS2 next updates the analog voltage--sort of a "fire and forget"
approach. A possible solution that occurred to me was to use a 20mS astable
in conjunction with a votage controlled monostable, but I'm not familiar
enough with what's out there to know which chips to use...I guess the hard
part of this for me is the voltage-controlled monostable: 0 to 5V in, 1mS
to 2 mS output. Anyone know how to implement this? I've not decided on
multivibrators, I'd just like to be able to control a servo with the PWM
analog output of the BS2.
The second part of this is to control a DC motor using the same analog-out
technique. I've been looking at the MC33030 chip. Has anyone tried using a
motor tach as the feedback on this chip? Does anyone know any reasons why
this chip can't be controlled with a 0 to 5V input? (I would, of course,
scale this up to 0 to Vcc with a transistor to the reference input)
Also, I have a couple of LM18200T's on the shelf, so if anyone knows how to
go from BS2 analog-out to PWM. I'd love to know the name of a good chip
here too.
The main type of information I'm looking for here is suggestions of chips to
look at...anyone?
Thanks,
Nic
Check out my page at http://members.tripod.com/~divelec/r3rcjs01.html
This setup has worked well for me for a couple of years. There is a schematic
and a downloadable
program. You may be able to use it with minor modifications for your project.
Carl
Original Message
From: Nic Nicholson <nicnicholson@p...>
To: Basic Stamps <basicstamps@egroups.com>
Sent: Thursday, July 20, 2000 6:54 PM
Subject: [noparse][[/noparse]basicstamps] multiple RC servos, & DC motor speed control
> I know this subject must have come up many times, but I haven't been able to
> find a satisfactory solution in any of the archives...
>
> I would like to be able to put the BS2 in between an RC receiver and the
> servos it controls, probably three of them, and also control a DC motor at
> the same time. It's the output part of this that's causing me problems.
>
> My intended solution is to make a circuit which takes 0-5V analog in (from
> the PWM of BS2) and will continue to put out a corresponding RC pulse until
> the the BS2 next updates the analog voltage--sort of a "fire and forget"
> approach. A possible solution that occurred to me was to use a 20mS astable
> in conjunction with a votage controlled monostable, but I'm not familiar
> enough with what's out there to know which chips to use...I guess the hard
> part of this for me is the voltage-controlled monostable: 0 to 5V in, 1mS
> to 2 mS output. Anyone know how to implement this? I've not decided on
> multivibrators, I'd just like to be able to control a servo with the PWM
> analog output of the BS2.
>
> The second part of this is to control a DC motor using the same analog-out
> technique. I've been looking at the MC33030 chip. Has anyone tried using a
> motor tach as the feedback on this chip? Does anyone know any reasons why
> this chip can't be controlled with a 0 to 5V input? (I would, of course,
> scale this up to 0 to Vcc with a transistor to the reference input)
>
> Also, I have a couple of LM18200T's on the shelf, so if anyone knows how to
> go from BS2 analog-out to PWM. I'd love to know the name of a good chip
> here too.
>
>
> The main type of information I'm looking for here is suggestions of chips to
> look at...anyone?
>
> Thanks,
>
> Nic
>
>
>
>
> the PWM of BS2) and will continue to put out a corresponding RC
> pulse until
You can use a PAK-VIII and bypass the PWM altogether. Just send the PAK the
"on" time and the "off" time and it will keep going. 8 channels in all.
Regards,
Al Williams
AWC
*Microcontroller Projects with Basic Stamps at
http://www.al-williams.com/awce/sbook.htm