Desktop Engraver

 

Objective: The client had an existing engraver that was designed in the late 1990's. The existing design used DOS and ATX style motherboards to control 4 stepper motors and provide the user with a black and white LCD screen. Parts for the old design were obsolete and hard to find. Client wanted to update the design to provide color graphics and enhanced functionality while reducing total manufacturing and support cost.

 

Result: Original Technology worked with the client to understand the objectives and goals for the project. Several design approaches were analyzed. In the end it was decided that the best and most cost effective approach was to redesign only the unit's electronics, replacing the hardware and software with a new, state-of-the-art design.

 

The new design was based on the BeagleBone Black (BBB) with a 7 inch color LCD touch screen. To interface the four stepper motors to the BBB a custom CAPE board was designed and fabricated. The complete electronics package mounted on the back of the display and resulted in significant power and cost savings.

 

The new BBB design supports both the existing ATX power supply and a new, smaller AC/DC power supply, enabling the design to be used for production as well as retrofit of field units.

 

A Debian image was created for the Linux OS. To provide the high speed I/O necessary to run the stepper motors, code was developed for the PRU-ICSS module of the AM3358 processor, and a new Device Tree Overlay (DTO) was created for the Linux image. Using this approach, stepper motor speeds of greater the 9000 steps/second were easily achieved.

 

The main application was developed using Python and Flask. Python provided the basic framework and machine logic while Flask provided a full featured GUI. The user interface was provided by a built-in Chromium web browser running in kiosk mode. Both static and dynamic web pages were designed using HTML, CSS, JavaScript, and Jinja2. One 'extra' feature of this web based design approach was that the engraver could now be run in remote mode over an Ethernet connection from a remote desktop or iPad allowing a wide verity of configurations and user input devices. The Python programming language also provided the added benefit of a database and a rich assortment of I/O, for reports, equipment performance monitoring, and software updates.

 

The result of the design effort was a new design that provided greater functionality, including color graphics, a larger LCD touch screen, real time auto scaling of text, real time display and selection of multiple fonts, auto fault reporting, lower power consumption, and state of the art electronics all while also significantly lowering manufacturing cost.