IC for Hobby Servo Control

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happy_99

Joined: 10 Oct 2003
Posts: 45

25 Jan 2004 9:24 hobby servo controller rs232

Is there any IC available which repeats a given pulse (pulse width in 1-2 ms range) at 20ms interval. This's required for a robotic project, in which 18 hobby servos are to be controlled.

Thank You

happy_99

CADDevil

Joined: 26 Jun 2001
Posts: 120

26 Jan 2004 13:34 hobby servo pic

You need something like PIC servo controller.

You can either do it yourself, Internet is full of schematics and code (use Google) or you can buy controllers like this

hxxp://www.matthiasm.com/hwServo.html

or similar.
18 servos is a lot for one controller, so I suppose that you will need two controllers and daisy-chain them.
With those controllers, you can command all servos from RS-232 port.

tgq

Joined: 15 Jul 2002
Posts: 305
Helped: 2

26 Jan 2004 14:40 servo controller ic

Here is a subroutine that waits 4x [numberin W] PIC cycle, include call + return. Good for servo control @4MHz clock (1µs cycle)
Set an output to 1, first put 250 in w (movlw .250), call the routine (call DlyFourW), then put the length from 0 to 255, re-call DlyFourW and finally set output pin to 0

DlyFourW
ADDLW 0FFh
BTFSS STATUS, Z
GOTO DlyFourW
NOP
RETURN

You can control the 18 servo one by one, this means from 18x1 to 18x2 ms, this gives # a normal repeat rate for each servo output
One PIC with enough pins is largely enough Laughing

Take just another pin for control input (RS232 for example)

happy_99

Joined: 10 Oct 2003
Posts: 45

30 Jan 2004 13:53 hobby servo control

Hi,

Thanks for all your replies. I just thought if there's a readymade chip then I can use it without wasting the time of the processor.

Thank You

happy_99

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30 Jan 2004 13:53 Ads

Taro

Joined: 28 Jun 2001
Posts: 147
Helped: 3

14 Feb 2004 5:45 pic hobby servo control

Have you every try somthing like Pic Basic Pro or Protron Pic Basic? It let you have easy way to programming PICmicro with BASIC Language, and of course, it's very easy and powerful.