ENGINEERING

Home of TurboCNC, the best open-source CNC control around...

 
web www.dakeng.com
 
  You are here:
  Homepage -> Hardware -> U-2 Stepper IC
Latest release of TurboCNC is v4.01 build 050312
released March 13
 

U-2 Stepper Translator IC


  Hardware Software  
Articles HOME FAQ's
  Manuals User
Forum
 
About
DAK
Ordering Contact
DAK
  Sitemap Links  

  This chip converts standard TTL step and direction signals to the phase signals used by a unipolar stepper motor for two axes.

Vdd:      5V +/- 10%
Vss:      0V (ground reference)
A Step:   Step input, step will be made on negative-going edge
A Dir:    Direction input, is read when step line goes low
A1-4:     Output for a unipolar motor in half-step sequence
B Step:   Step input, step will be made on negative-going edge
B Dir:    Direction input, is read when step line goes low
B1-4:     Output for a unipolar motor in half-step sequence
MCLR:     Master clear and Reset.  This line must be held high for normal operation.  Pull low to reset the chip.
OSC1/OCS2: Clock inputs - see diagram below for RC oscillator hookup.
Unused:   Just like it says, leave this pin floating if you like.  In Hakan Ertan's version, this selects full/half stepping.

  Source code for the U-2 (a PIC 16F84 running a dedicated program) can be downloaded here and you can program the IC's yourself.  If you don't have a PIC programmer or are feeling lazy, you can buy pre-programmed and tested chips from me for $10 apiece.  See the ordering page for details.

   Hakan Ertan has uploaded code that adds full/half-step selection on pin 3.  Download his code here.  He has also submitted code for a version that runs on the PIC12C508A microcontroller.

  Here is a sample circuit schematic using the U-2 as a stepper driver for two unipolar motors (click view full-size)

NOTE:  Don't fudge the value of the RC pair on the OSC1 pin.  It's setting the clock speed of the chip.  A 22 pF cap looks a chili bean with two wires stuck in it, and has an underlined 22 .

  The step pin needs to be held low for 20 clock cycles minimum in order to guarantee that the chip will read it in time.  For the 2.5 MHz clock speed in the circuit shown, this works out to about 32 uS.  For TurboCNC, I set the pulse width to 40 uS just to be safe.

 
 

 

 

2001-2015 DAK Engineering.  

All rights reserved.

This page last updated on January 11, 2015 . 

Email: admin@dakeng.com