Introducing the GCUSB-nStep2 stepper motor controller

Provides for:

USB interface

Standalone operation

Modular plugin expansion

Wireless interface for bluetooth communications

Display with buttons and speed control, 16 char/2line

Adaptable for other uses (home sensor, rs232)

See ‘Technical Information’ below

Temperature sensor and temperature based focus (provided by ASCOM driver)

ASCOM driver supported over USB or wireless

Base module remembers all settings across power on’s

Firmware is field flash upgradeable

See GCUSB-nSTEP page for description of ASCOM driver

The base module

The unit with optional wireless, temperature probe and display module attached.

At this time the display unit circuit boards are expected to be available end of Jan 2011.

The Bluetooth module

Not much to see, led indicates paired and connected status.

Range 20 meters or 100 meters available

The Display unit

Buttons usage:

Upper left: Next menu

Upper right: Previous menu

Lower left: focus or change current menu item

Lower right: focus or change current menu item

The menu structure:

Top level menu showing:

Current position

Probe temperature

Step type (W/H/F)

Coils On/Off Current = 0 = off

Phase select: Current = 2

The current steps/second (149)

The stepper will move if the In/Out buttons pressed only in on top level menu.

The current position will update continuously if the main module or display module in/out buttons are pressed

The current steps/second will show the main modules rate if main module in/out buttons pressed.

The twist dial at top:

Set current step rate (now 88)

Will only range from 6 to Max Speed

(see below)

Select step type:

Top = W = Wave Stepping

Bottom = H = Half Stepping

Choices: Wave, Half or Full torque

Select Coils On/Off after movement

Top = 0 = Off

Bottom = 1 = Leave on

Set phase drive order:

Top = 2

Bottom = 1

Choices = 0, 1 or 2

This accounts for the wiring order of the stepper.

Set display brightness

Range = 0 (off) through 31

Set display contrast

Range = 14 through 31

Backlight on time

Range 10 through 310 seconds

After last button is pressed keep backlight on for this length of time

Set max step rate

Range 99 through 1496 steps/second

Force zero current position

Press up/down to zero, will confirm on next menu if up/down pressed.

To cancel, press menu select buttons

Confirm force zero position

Press p/down to zero.

To cancel, press menu select button

The bottom of the board

Technical Information:

1) Stepping rates

The unit provides for a wide range of stepping rates, some of which can drive drastically faster than most steppers can handle.

The maximum rate is 1496 steps/second, the minimum rate is 5 steps/second. The maximum rate is controlled in the ASCOM driver and in the hand unit itself.

The display module provides for a more limited range of step rate selection, offering the choice of 25 speeds from 1496 to 6 steps/second.

2) Stepper driver

The unit uses high voltage/medium current mosfet output drivers capable of driving 1 AMP/phase.

3) Optically coupled when PC attached

When connected to the PC/Mac the output stages are isolated from the processing side via optical coupling. The 12V supply is only used for the motor and the USB 5V is only used for the PIC, wireless and display module.

3) Standalone operation and Wireless

The base unit can be jumpered for running standalone without USB or wireless interface.

The base and optional modules then take power from the 12V supply.

Standalone operation uses same firmware load as wireless operation.

4) Wireless

The expansion wireless module is based on the Roving Networks RN-41 (for 100m) or the RN-42 (for 10m-20m) for wireless interface.

At this time the USB and Wireless interfaces are mutually exclusive, both cannot communicate at the same time. It is two separate and distinct firmware modules that is loaded into the base unit.

5) Expansion ports

The two expansion ports shown provide for 5V, GND, TX and RX TTL serial interfaces. This means that adapting the unit to rs232 DB9 serial interface in place of wireless is a simple add on module that converts rs232 voltages to TTL voltages. No firmware changes are required.

Pinouts (looking into the connector, upper left = pin 1)

Pin 1: 5V

Pin 2: Module RX (To module)

Pin 4: Module TX (From module)

Pin 4: GND

The Display port runs at 19.2k baud and the Wireless port runs at 9600 baud. Both are 8/N/1.

6) Expansion port digital I/O