View previous topic :: View next topic |
Author |
Message |
ms_10011101
Joined: 21 Feb 2005 Posts: 25
|
Posted: Mon Feb 21, 2005 5:15 pm Post subject: Newbie PWM multiplexing inquiry |
|
|
I'm putting together an application on an ATmega8535 that requires 4 PWM channels and a timer (robot legs). The PWM requirements are minimal- just small motor control. As a complete newbie I realized too late that ALL timers are used by 4 channels of PWM and am now on the hunt for a solution. Since at least two PWM channels will be operating in a parallel fashion, it seems muliplexing the output is a solution (IE: legs 1, 2 and 3 moving back at same rate while 4 moving forward). My plan is to set 1 forward PWM channel and 1 reverse, then multiplex/enable (independantly) legs according to position. Question is-- What chip to use for multiplexing (addressable 1 in and 1 - 4 out)? |
|
Back to top |
|
|
DJD XTREEM
Joined: 24 Jun 2004 Posts: 190 Location: 127.0.0.1
|
Posted: Mon Feb 21, 2005 10:08 pm Post subject: |
|
|
are you using servo's for the legs of the robot??
Because when you are you can use the servo command in bascom.. that way you should be able to control 16 servo's with just 1 timer..
otherwise you could consider using some soft pwm stuff.. more info look @ my program in the Look a like rcx robot project..
Look in my signature for the direct link.. _________________ Bascom AVR 1.11.8.8 full version
STK500 Programmer
ISP Programmer |
|
Back to top |
|
|
ms_10011101
Joined: 21 Feb 2005 Posts: 25
|
Posted: Mon Feb 21, 2005 10:57 pm Post subject: Newbie PWM multiplexing inquiry |
|
|
No, no servos. I'm using drill motors and LMD1800Ts to drive them (needs to carry 1-2 Kilo payload). I thought of using soft PWM--even set it up on a 2313 to verify it would work, but the datasheet scared me... I think I read there that Atmel recommends against this because it "uses too much mcu time". Anyway, it got me to thinking and I figured that two "always on" channels, switched as I previously described, was a "neater" solution--just SHIFTOUT nibble through selector chip (whatever that might be)!
PS-- Saw no link in signature, please post. |
|
Back to top |
|
|
@gsan
Joined: 22 Apr 2005 Posts: 1 Location: Jogjakarta
|
Posted: Wed May 25, 2005 4:48 pm Post subject: |
|
|
Can anyone give me command bascom to control servo motor? |
|
Back to top |
|
|
Olli
Joined: 10 Jun 2005 Posts: 10 Location: Germany
|
Posted: Sun Jun 12, 2005 8:24 pm Post subject: |
|
|
@gsan wrote: | Can anyone give me command bascom to control servo motor? |
just check "config servos" on the help pages for examples
(this seems to work only up to 14 Servos, not to 16 . . and the timing is not as perfect as i should be, that you can use it with some parameter tuning) |
|
Back to top |
|
|
DJD XTREEM
Joined: 24 Jun 2004 Posts: 190 Location: 127.0.0.1
|
Posted: Mon Jul 04, 2005 10:51 am Post subject: |
|
|
Olli wrote: | @gsan wrote: | Can anyone give me command bascom to control servo motor? |
just check "config servos" on the help pages for examples
(this seems to work only up to 14 Servos, not to 16 . . and the timing is not as perfect as i should be, that you can use it with some parameter tuning) |
That is what i found out too.. If you try to configure servo 15 and servo 16 there are compiling errors..
I'm planing to make a 16 servo controller that is controlled by serial commands..
Also i'm working again on my 6 soft pwm program that i make a few months ago.. Because i haven't implemented the serial comunication yet..
to ms_10011101 or something like that
if you use an external processor like the 2313 and clock it high like 8 or 12 mhz. It could be done on this way.. But i'm sorry haven't the serial comunication already..
This is my way to make 6 channels of pwm on my robotics board.. Just by rs232 comunication to another chip that has the only job to generate pwm and direction settings.. _________________ Bascom AVR 1.11.8.8 full version
STK500 Programmer
ISP Programmer |
|
Back to top |
|
|
eddy
Joined: 09 Apr 2004 Posts: 67 Location: Near Chicago, IL USA
|
Posted: Sun Oct 02, 2005 2:33 pm Post subject: |
|
|
What frequency are you getting on those software PWM channels? I've experimented with software PWM but I could only achieve a few hundred hertz with 8-bit resolution. I would like around 2KHz frequency...
Eddy
http://www.wrighthobbies.net _________________ Eddy Wright
Wright Hobbies, LLC
http://www.wrighthobbies.net |
|
Back to top |
|
|
DJD XTREEM
Joined: 24 Jun 2004 Posts: 190 Location: 127.0.0.1
|
Posted: Mon Oct 03, 2005 6:28 am Post subject: |
|
|
I can't tell you for the moment because i'm still bugging with reading rs232 commands as quick as possible.. This because i want to control the PWM by rs232.. But the frequency will totally depend on how much rs232 you have to decode and how high your clock frequency will be.. If the speed will exceed 1 mhz on a 8mhz clock you can simpely get speed back with wait statements.. Or maybe setting a timer that gives a pulse every while you need to renew your pwm ... _________________ Bascom AVR 1.11.8.8 full version
STK500 Programmer
ISP Programmer |
|
Back to top |
|
|
ALJ-1108
Joined: 08 Nov 2005 Posts: 7 Location: USA RICHMOND,TEXAS
|
Posted: Tue Jan 24, 2006 3:57 pm Post subject: more pwm outputs |
|
|
Hello all,
There are some 8 bit pwm chips that are buss driven to allow as many pwm outputs to your hearts desire (Ixys makes them)...
The frequency is definable by the crystal attach to the chip itself.. At this moment I can't remember the part number but I think it is the Ixp610 or something to that effect... _________________ Willing to help if I can... |
|
Back to top |
|
|
eddy
Joined: 09 Apr 2004 Posts: 67 Location: Near Chicago, IL USA
|
Posted: Tue Jan 24, 2006 8:59 pm Post subject: |
|
|
It's the Ixdp610
http://www.ixys.com/91600.pdf
That's an interesting chip. So you can stack them up on the same buss to produce as many PWM channels as you want. I'll go see what the cost is.
Eddy _________________ Eddy Wright
Wright Hobbies, LLC
http://www.wrighthobbies.net |
|
Back to top |
|
|
ayu
Joined: 04 Nov 2006 Posts: 10
|
Posted: Sun Nov 05, 2006 2:58 am Post subject: 16 channel serial servo controller for robotic applications |
|
|
Hi,This a asembly language to built a SSC(Serial servo contorller),
http://www.seattlerobotics.org/encoder/200106/16csscnt.htm
I had tried,but just only adjust to 125 and 126 to 255 can't apply to pulses,
now, hope to solved the 2 questions,
1, What the bug,I don't know?Hope someone told me why?Thanks.
2,Can we try basic language to succeed this controller? Thanks.
Last edited by ayu on Tue Nov 07, 2006 1:50 pm; edited 2 times in total |
|
Back to top |
|
|
DJD XTREEM
Joined: 24 Jun 2004 Posts: 190 Location: 127.0.0.1
|
Posted: Tue Nov 07, 2006 12:56 pm Post subject: |
|
|
I'm busy with an 8 channel PWM servo controller.. If that suceed i will look closer to get a 14 channel version on the market..
How much time do you have left.. Because i'm a very busy men.. Always working is not good.. But sometimes it's the only way to get things done :p _________________ Bascom AVR 1.11.8.8 full version
STK500 Programmer
ISP Programmer |
|
Back to top |
|
|
ayu
Joined: 04 Nov 2006 Posts: 10
|
Posted: Tue Nov 07, 2006 1:58 pm Post subject: |
|
|
DJD XTREEM wrote: | I'm busy with an 8 channel PWM servo controller.. If that suceed i will look closer to get a 14 channel version on the market..
How much time do you have left.. Because i'm a very busy men.. Always working is not good.. But sometimes it's the only way to get things done :p |
Hi,DJD XTREEM
If the guestion is to me,I'm free ,hope your kindness to solve the problem and teach me? ok? Thanks a lot.
Best regard,
ayu |
|
Back to top |
|
|
|