BB Q10 Keyboard-to-I2C Software

This software is designed to interface a BB Q10 keyboard matrix as a I2C slave.

The key presses are put on a FIFO, which can be queried over I2C.

The software also allows for basic configuration of the behaviour.

The software also controls the backlight of the keyboard.

See Protocol for details.

Building

See the targets directory for a list of available targets.

git clone https://github.com/arturo182/bbq10kbd_i2c_sw.git
cd bbq10kbd_i2c_sw
make TARGET=<target>

Implementations

Here are libraries that allow interaction with the boards running this software:

• Arduino
• CircuitPython
• Rust (Embedded-HAL)

Protocol

The device uses I2C slave interface to communicate, the address can be configured in app/config/conf_app.h, the default is 0x1F.

You can read the values of all the registers, the number of returned values depends on the register. It's also possible to write to the registers, to do that, apply the write mask 0x80 to the register ID (for example, the backlight registred 0x05 becomes 0x85.

The FW Version register (REG_VER = 0x01)

Data written to this register is discarded. Reading this register returns 1 byte, the first nibble contains the major version and the second nibble contains the minor version of the firmware.

The configuration register (REG_CFG = 0x02)

This register can be read and written to, it's 1 byte in size.

This register is a bit map of various settings that can be changed to customize the behaviour of the firmware.

Bit	Name	Description
7	CFG_USE_MODS	Should Alt, Sym and the Shift keys modify the keys being reported.
6	CFG_REPORT_MODS	Should Alt, Sym and the Shift keys be reported as well.
5	CFG_PANIC_INT	Currently not implemented.
4	CFG_KEY_INT	Should an interrupt be generated when a key is pressed.
3	CFG_NUMLOCK_INT	Should an interrupt be generated when Num Lock is toggled.
2	CFG_CAPSLOCK_INT	Should an interrupt be generated when Caps Lock is toggled.
1	CFG_OVERFLOW_INT	Should an interrupt be generated when a FIFO overflow happens.
0	CFG_OVERFLOW_ON	When a FIFO overflow happens, should the new entry still be pushed, overwriting the oldest one. If 0 then new entry is lost.

Defaut value: CFG_OVERFLOW_INT | CFG_KEY_INT | CFG_USE_MODS

Interrupt status register (REG_INT = 0x03)

When an interrupt happens, the register can be read to check what caused the interrupt. It's 1 byte in size.

Bit	Name	Description
7	N/A	Currently not implemented.
6	N/A	Currently not implemented.
5	N/A	Currently not implemented.
4	INT_PANIC	Currently not implemented.
3	INT_KEY	The interrupt was generated by a key press.
2	INT_NUMLOCK	The interrupt was generated by Num Lock.
1	INT_CAPSLOCK	The interrupt was generated by Caps Lock.
0	INT_OVERFLOW	The interrupt was generated by FIFO overflow.

After reading the register, it has to manually be reset to 0x00.

Key status register (REG_KEY = 0x04)

This register contains information about the state of the fifo as well as modified keys. It is 1 byte in size.

Bit	Name	Description
7	N/A	Currently not implemented.
6	KEY_NUMLOCK	Is Num Lock on at the moment.
5	KEY_CAPSLOCK	Is Caps Lock on at the moment.
0-4	KEY_COUNT	Number of items in the FIFO waiting to be read.

Backlight control register (REG_BKL = 0x05)

Internally a PWM signal is generated to control the keyboard backlight, this register allows changing the brightness of the backlight. It is 1 byte in size, 0x00 being off and 0xFF being the brightest.

Default value: 0xFF.

Debounce configuration register (REG_DEB = 0x06)

Currently not implemented.

Default value: 10

Poll frequency configuration register (REG_FRQ = 0x07)

Currently not implemented.

Default value: 5

Chip reset register (REG_RST = 0x08)

Reading or writing to this register will cause a SW reset of the chip.

FIFO access register (REG_FIF = 0x09)

This register can be used to read the top of the key FIFO. It returns two bytes, a key state and a key code.

Possible key states:

Value	State
1	Pressed
2	Pressed and Held
3	Released

Version history

v0.3:
- Change values sent for mods if CFG_REPORT_MODS is enabled so they don't overlap the buttons
- Send different value for left and right shifts if CFG_REPORT_MODS is enabled
- Change FIFO size to 31 so it's reported correctly in REG_KEY if FIFO is full

v0.2:
- Add support for KEY_LEFT2 and KEY_RIGHT2
- Add the Keyboard FeatherWing target

v0.1:
- Initial release