PDA

View Full Version : Phidget 4-Servo Controller & OSMC



rogueind
10-30-2007, 02:45 PM
Hey All,

I'm looking to use the 4-Servo Controller with the OSMC (Open Source Motor Control). (1 servo channel to each OSMC) Has anyone used these two together? Looking at the specs on the OSMC website, it takes PWM as a control. Good Idea? Bad Idea? Other Thoughts? I did a quick google search and of these forums, but didn't notice anyone specifically using these two together. This is my first post, so please be gentle =).

--Brian.

Alex
10-31-2007, 01:11 PM
It doesn't look like the OSMC takes an RC signal directly as a control, so you cannot use the 4-Servo Controller, at least not directly. Taken directly off of Robot Power's product page for the OSMC:

(http://www.robotpower.com/products/osmc_info.html)
The OSMC is a simple H-bridge power amplifier. It does not have any on-board logic to interpret RC or other commands. An external logic interface is required to translate command inputs into the PWM signals needed to drive the board.

The strange thing about that page is that it really ambiguous about what sort of signal is required though. However, if you look at the image below (taken from the OSMC product page), it definitely shows an interface board between the RC controller and the OSMC:


http://www.robotpower.com/images/mag-combo-lg.jpg

rogueind
10-31-2007, 01:23 PM
The thing that i am confused about is on the OSMC website, it speaks about using "command inputs into the PWM signals needed to drive the board". Is there any kind of PWM "Standard" for these types of things? The other device in the photo is what the call a Dalf - "The Dalf provides the interface between various command input sources and generates PWM signals to drive two OSMC boards". So, makes me think that if the Phidget servo controller spits out "standard" PWM signals, the OSMC may handle them?

I do appreciate all the help!
Thanks!

rogueind
10-31-2007, 03:19 PM
Actually, I was way wrong on the "other device". The other board pictured there is a ┬ÁMOB. This converts standard R/C Servo Controls to what the OSMC is expecting (which is PWM with DIR signals). Sorry about the confusion. This also answers my original question. So for future reference, i'm guessing you'd need the 4-servo phidget controller, and something similar to the ┬ÁMOB (which is discontinued), and finally to the OSMC.

Thanks, and sorry for the confusion.

Alex
10-31-2007, 03:27 PM
Hey, no worries. It's all part of the learning process:)

Thanks for letting us know what you found!

Dave
11-05-2007, 03:04 PM
Yeah, it looks like you could preform the translation with just about any microcontroller dev board. You just need to measure the pulse length from the RC signal (1ms-2ms) and convert it to a PWM duty cycle (0%-100%) plus a direction signal.