Today, we're taking the third step in sharing Ember. Ember's electronics and firmware are now open-source and are available for you to download, inspect, modify, and make improvements. The electronics are shared under a Creative Commons Attribution-ShareAlike license, the same license under which we've shared Ember's resin and mechanical designs; the firmware is licensed under GNU GPL (see the source code itself for the full details).
Most of Ember’s electronic components are located on two PCBs. The main board integrates a clone of the BeagleBone Black and an AVR-based motor controller. The major changes from a stock BeagleBone are the addition of a USB hub (to support the included WiFi adapter), double the flash memory (8GB), and improved power management. A satellite board in the front panel controls its OLED display and ring of LEDs using a second AVR. The Sitara and the AVRs communicate via I2C.
The electronics are available here in three different packages for each of the four boards:
1) the design files
2) the schematics and PCBs
3) the bill of materials, approved vendor lists, and assembly drawings
Ember runs custom firmware in the main (Sitara) processor as well as in the AVR controllers for the front panel displays and the motors that drive the build head and resin tray. The architecture of the Sitara firmware is shown below.
The print engine controls the printing process by sending commands to the motors and slice images to the projector. It uses a hierarchical state machine and reports state changes to an event handler that notifies UI components to update their screens. The event handler also responds to user input (button presses and commands), and motor and timer events, by notifying the print engine to make the appropriate state changes. The web client sends status to emberprinter.com and accepts commands from it. A web server provides an interface for desktop applications using a USB or network connection.
Fully opening the design of a precision tool as complicated as Ember is uncharted territory for us. And, we know this isn’t necessarily easy - Ember’s main electronics are a 6-layer board and the design files are in the format of a professional tool. While it might also be difficult to run the firmware without direct access to Ember itself, we have provided a link to the SD card image that could be used on a stock Beaglebone Black for development. However difficult it might be to come along, we hope you’ll recognize our commitment to an open platform and commitment to making the entire field of additive manufacturing better.