This a the new Laser Interface PCB. It adds a lot of new features including the stepper motor drivers. This board is designed to reduce the wiring requirement of a home build laser cutter/engraver. This should significantly reduce the cost of a laser cutter. If you use this with EMC2 (free) you should be controlling your laser for less than $100. There is a video at the end of the post.
This is a standard 25 pin ‘D’ connector. The pinout is compatible with PC control (Mach3, EMC2) or the FSE Retina Engrave controller.
Stepper motor Drivers
The PCB provides three slots for Pololu stepper motors drivers. It can use the A4983 or the A4988 stepper drivers. The PCB provides the logic power so you use the cheaper versions of the boards. These drivers can provide up to 2amps of power at resolutions up to 1/16 step. The microstep mode is easily adjustable through rotary DIP switches. These are placed along the edge with the control connector so they can be made accessible through the enclosure wall. If you ever blow a driver, you can simply replace the broken one. There is a built in fan to cool the drivers that cools them to within a few degrees of the ambient temperature.
The board creates a safety loop of switches to protect the user and laser tube. The loop runs through the emergency stop button, the cover switch and the water flow switch. If any of these items are are not in the run position or if there is a break in the loop, the laser tube cannot be enabled.
Laser Power Control
The board allows two different laser power control modes. The default mode is via a remotely located manual potentiometer. This is usually mounted on the front panel. You can also use a switch to change to PWM mode. This allows an external controller to provide a digital PWM power level control. This switch would be located on the front panel. The PWM signal can be configured to use pin 14 or pin 15 on the 25 pin connector.
Dual Relay Drivers
The board has two high current MOSFETs that can be used to drive external relays. these are controlled via pins 1 and 8 on the 25 pin control connector. These are typically used to control assist air and exhaust blowers. They can easily be configured through Mach3 or EMC and G-Code as if they were mist and flood coolant devices.
Laser Power Supply Connector
There is a direct 1:1 connection to standard laser power supplies. The board takes car of connecting all the grounds and safety interlocks.
There is a three pin terminal block to connect to the water switch. The switch can be a simple mechanical switch, plus there is a 5V power source to use if you want to power a more complex water monitor.
There is a connector dedicated to the enclosure connections for the limit switches and cover interlock. The board provides the pull up resistors for these items so they can be wired in a mode where a break in the wiring would trigger signal an open circuit. The pull up value can be either 5V or 3.3V.