CharaChorder Engine Dev Board

CharaChorder Engine Dev Board v1.0

The CharaChorder Engine Dev Board v1.0 is designed for testing the features of the CharaChorder Engine. This board has a 3x4 matrix of momentary push-buttons, with the option of using MX switches instead. The primary microcontroller is an ATSAMD11D14A, which connects to the 3x4 matrix, provides a USB output, and connects to the CharaChorder Engine through the 3 interfaces. A set of jumper pins are provided to switch between the UART and the I2C interfaces, while the SPI interface has dedicated traces. A second USB-C connector is available for exploring the USB interfaces provided directly by the CharaChorder Engine itself. Power is supplied by the USB-C connector, and an onboard regulator provides a stable 3.3 volt power supply to the development board.

Footprint of 10.16 mm x 20.32 mm

Our CharaChorder Engine RevB3 has dimensions of 10.16 mm by 20.32 mm with castellated holes for mounting and providing power and communications. The footprint is intended to be fit within standard keyboard electronics boards.

Power Supply

The CharaChorder Engine should be powered with a stable 3.3V supply. The input/output logic also operates at this 3.3V voltage level. The Engine consumes less than 20mA, and in deep sleep less than 500µA.

Interfaces - UART, I2C, SPI

There are multiple interface options for communicating with the CharaChorder Engine. Three low level interfaces, UART, I2C, and SPI are available to provide support for a wide range of primary chipsets. Each of the communication protocols supports similar schemas for configuring, submitting, and receiving data. The API provides a method to inform the Engine of the key mapping of the keyboard. Then the primary controller can submit a 128-bit map of the currently pressed keys with an optional time parameter in milliseconds. When the Engine has a data ready, the DR flag is thrown to indicate to the primary microcontroller that there is a result ready. There are a few options for the data format. For HID Keyboard outputs, the Engine can provide a sequence of standard 9-byte HID Keyboard reports to forward through the primary microcontroller’s USB HID connections. Similarly, the Engine can also provide HID Mouse reports to be routed to the user’s computer.

USB Device Interface

The CharaChorder Engine provides the option for a USB device interface with HID Keyboard, HID Mouse, and CDC Serial functionality. This could be merged with the primary microcontroller of the keyboard through a USB Hub chip to provide the simplest integration.

Store over 60,000 custom chordmaps

The Engine comes with enough onboard storage to hold over 60,000 chordmaps. The chordmap outputs can contain up to 230 characters , 115 sequential commands, or a measured combination of both. Currently, characters can include those within the ASCII/ISO-8859-1 (Latin1) character set, which includes most West European languages. The modules can be pre-programmed with a base set of chordmaps. However, the chordmaps can be updated by users through our web based manager with the addition of a CDC communication bus on the USB. Chordmaps can also be added and edited directly with ‘Impulse’ chording through the keyboard interface as well.

Specify up to 120 logical keys

Keys on the keyboard need to be mapped in order to represent chords. Each keyboard layout is unique, so our module has the capability to allow keys to be mapped to each layout. Most full sized keyboards have 104-105 keys. The Engine provides up to 120 logical keys for mapping binary inputs.