SD 20 servo driver

Community General Discussions
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1

Hi guys,

Recently I posted a post on the forum about controlling a larger amount of servos (18). A few people suggested the SD20 servo driver chip which looked awesome so I went ahead and purchased a few of these chips. I have made the board and setup my picaxe 40x2 to send out the commands via i2c however I have ran into some problems that I just can’t work out. All of the servos do seem to move to the given position but they seem to lack greatly in power. Second problem is that the servo movement range is greatly decreased. I have setup the sd20 the way the documents say to do so and I have tried Manu power sources. I have tried unplugging all servos but one and trying a brand new servo yet nothing has seemed to fix my problem. I have tried hooking up a few of the servos to the picaxe21x1 project board and the sevo range is fine and they have a lot of power. Really confused as to what may be going on here. Has anyone else had this problem before?

Thanks in advance! :slight_smile:

2

I assume that this is done

I assume that this is done in standard mode. Have you tried to use expanded mode with the registers set to act like it’s in standard mode? I see it explained on page three of this SD20 document.  I don’t know if that will address the lack of power or not.

3

** Do u guys know how to hook**

 Do u guys know how to hook up sd20 to pic28x1 projectboard?

i hooked it up the way it shown on the manual…then i wrote this:

 

i2cslave $C2,i2cfast,i2cbyte     

writei2c 1,(1)

 

wait 1

writei2c 1,(254)

 

wait 1

but its just not working at all…

 

4

If you haven’t seen it

If you haven’t seen it already, this document on Using I2C with Picaxe may be helpful.