Overview
The MC433 is a 4-Axis Unipolar stepper motor controller that converts step/direction inputs to jumper selectable wave, full or half step 4-phase motor control.  Connecting directly to a PC's parallel port the MC433 uses ultra low on resistance Power MOSFETs (0.044ohm) capable of handling high amperage steppers with ease.  By regulating the current delivered to each phase through PWM the power needs of a particular stepper can be optimized for an intended application without the need for power sapping load resistors.  PWM initial on time, chop duty cycle and duty cycle slew rate are changed using on board potentiometers.  The PWM signal delivered to each axis is controlled by a dedicated 8bit RISC processor (ATmega168) that can be field upgraded with new control algorithms using a programming adapter.  An I2C TWI communications port allows an external TWI controller to communicate with each motor controller setting step mode, step, PWM parameters and turn off conditions on an individual motor basis.  Safety features include automatic duty cycle reduction during idle periods, motor shut off after 20 seconds,  and duty cycle slew rate adjustment for slow step rates.  The MC433 is available with an optional onboard G Code processor.  Additional accessories include several relay daughter cards, joystick input, 4-axis large LED display and a high performance G Code processor for dedicated ultra high speed half step applications.  The onboard G Code processor allows OEM's to develop their own custom control algorithms and monitoring systems without relying on a attached PC.

Features
    o  Unipolar Stepper Motor Controller
    o  10A continuous, 33A Peak
    o  4-Axis X, Y, Z and A
    o  Wave, Half and Full (High Torque) step
    o  PWM variable on time, chop duty cycle and duty cycle slew rate
    o  Limit switch detection on each axis - routed to Parallel Port
    o  Stepper motor input voltage 7-35VDC
    o  Noise reduction snubber on each input
    o  4 Open NPN outputs from Parallel Port
    o  PC Parallel Port Interface
    o  Logic power supply 8-15VDC
    o  Relay daughter card interface
    o  I2C TWI Communications Port
    o  ISP Programming Port
    o  Small form factor (3.85x3.00in)
    o  Optional features:
              o  On Board G Code Processor
              o  RS-232/RS-485 Serial Interface
              o  Software controlled step mode selection
              o  Joystick interface
              o  3 Analog input channels

Component Layout

Description
The MC433 is a 4-Axis unipolar stepper motor controller that converts step/direction inputs to jumper selectable wave, full or half step 4-phase power control.  Each of the four phase coils of a unipolar stepper motor is connected to an IRF540NS Power MOSFET switch.  The IRF540 is capable of 10A continuous current load with the ability to peak at 33A.  Each phase is pulse width modulated (PWM) to allow operation over a 7 to 35 volt range.  PWM adjusts average current delivered to the stepper motor to better match the resistance/inductance of the motor without the need for load resistors.  This ensures maximum power is delivered to the motor over a range of load conditions and motor types.  PWM parameters are adjusted using three potentiometers - initial on time, chop rate duty cycle and duty cycle slew rate verse step rate.  Chop rate is fixed at 12KHz.   On time is the amount of time a switch remains on before PWM operation takes over – this allows the current to build to a maximum level as quickly as possible.  Duty cycle is the percentage of on-time to off-time at a given chop frequency.  Duty cycle is used to set the average current delivered to the motor.  Duty cycle slew rate adjusts the duty cycle based on the duration of a step.  As the step rate slows down (motor turns slower) the duty cycle is adjusted to deliver less power to the motor thereby maintaining constant current.  Each motor can be individually set for wave, full, half step mode or be disabled by setting two jumpers on a four pin header. 

The MC433 is controlled via a PC compatible DB25 parallel port interface connector. The Parallel port interface has four Step/Direction inputs, four auxiliary outputs and four limit switch inputs. The four auxiliary outputs are connected to a Relay Adapter connector and an open NPN control connector.   Limit switch inputs are connected to four  0.1” pin headers  with pull up resistors  -  pulling the limit switch input to ground deactivates a stepper motor. 

A I2C TWI communicatons port allows an external TWI controller to communicate with each motor control processor individually to set step mode, step, PWM parameters and turn off conditions. 

Downloads/Revisions
The following technical datasheets, hardware and software downloads are available.  For information on how to download the latest Motor Controller software or G Code processor software contact support@soc-machines.com - this code is sent via email request only.  Note - MC433 units shipped before July 10th should upgrade to the latest release.  Motor Controller Version 0.95 is scheduled for release December 6th - this release will include MC433Setup.exe:

       Motor Controller  - Current Software Version:     V0.87      Released August 10, 2006
       G Code Processor  - Current Software Version:   V1.56      Released August 31, 2006

       MC433 Rev 1.1/1.1b Technical Hardware Manual -> MC433 Rev 1.1b Manual
       MC433G Technical Hardware Manual -> MC433G Technical Manual
       MC433 Test Utility MC433Test.exe (V0.85) -> MC433Test_R85.zip

       MC433 Programming Utility MC433Prog.exe -> MC433Prog.zip

       Motor Control Processor -> ATmega168 Processor Datasheet
       On Board G Code Processor -> ATmega644 Processor Datasheet
       GC400 DSP Processor -> Blackfin ADSP-BF532 DSP Processor Datasheet