Open Servo

[joe61]

Anyone here used Open Servo controller boards? The idea of controlling a bunch of servos with I2C sounds intriguing, but I don't know how difficult it would be to swap them for the board a servo comes with, etc.

Joe

[Soeren]

Hi,

Anyone here used Open Servo controller boards? The idea of controlling a bunch of servos with I2C sounds intriguing, but I don't know how difficult it would be to swap them for the board a servo comes with, etc.

While I haven't used the Open Servo boards, I can see their purpose in some applications. However, the idea of first having to buy servos and then have to rip out what is a large part of its price, to replace it by yet an outlay seems to me to be a whacky thing, if you pardon my French.

If you want to control "a bunch" (however many that may be), by IIC, why not program an IIC to the number of servos you need controller into a cheap microcontroller?
It will be cheaper, as you just need the controller, an X-tal and 3 caps (or use the clock from your main controller) and that way there's no need to modify the servos.

You'll probably be using an Atmel chip, but as an example, with eg. a PIC16F628 or similar 18 pin chip, it would be a one evening project to make an IIC->servo control for up to 13 servos (14 if you use the main controllers clock and 15 if you can get enough precision from the internal oscillator)

[joe61]

While I haven't used the Open Servo boards, I can see their purpose in some applications. However, the idea of first having to buy servos and then have to rip out what is a large part of its price, to replace it by yet an outlay seems to me to be a whacky thing, if you pardon my French.

Yeah, I figured there must be an advantage somewhere though, wondering what it is.

If you want to control "a bunch" (however many that may be), by IIC, why not program an IIC to the number of servos you need controller into a cheap microcontroller?
It will be cheaper, as you just need the controller, an X-tal and 3 caps (or use the clock from your main controller) and that way there's no need to modify the servos.

You'll probably be using an Atmel chip,

Atmel has an application note that shows how to do pretty much that, and it works well enough. Mostly I'm just wondering what the advantage is to using the Open Servo boards.

but as an example, with eg. a PIC16F628 or similar 18 pin chip, it would be a one evening project to make an IIC->servo control for up to 13 servos (14 if you use the main controllers clock and 15 if you can get enough precision from the internal oscillator)

I've seen a couple controllers that used a PIC something-or-other to do that. I've wanted to try them for a while but it's too much of a pain to boot Windows just to run the programming environment. However,  I got a couple picaxe chips a few days ago, and they can be programmed easily in linux, so I'm working my way through the manual now trying to get the lay of the land. Having to use Basic is taking some getting used to as well, but it looks like it's going to be an interesting time.

Joe

[Soeren]

Hi,

Yeah, I figured there must be an advantage somewhere though, wondering what it is.

Full control over the software. Great if you want to experiment with control strategies and algorithms, add control protocols or whatever.
And you can use it if you want to build a servo from the ground up - perhaps something that don't fit in a standard servo shell.
For people who just want a regular servo with the standard servo protoco, there's no reason to use O.S.

I've seen a couple controllers that used a PIC something-or-other to do that. I've wanted to try them for a while but it's too much of a pain to boot Windows just to run the programming environment. However,  I got a couple picaxe chips a few days ago, and they can be programmed easily in linux, so I'm working my way through the manual now trying to get the lay of the land. Having to use Basic is taking some getting used to as well, but it looks like it's going to be an interesting time.

You could have an extra (old) PC/laptop/net book runnig XP. When I have to measure while I program, I usually have oscilloscope, LSA or whatever running on a net book - quite handy.

Have fun with the Axe's