Keyboard issues

Key Matrix

The Librem 14 key matrix layout is usually relevant for troubleshooting issues like:

• Pressing one key triggers other keys.

• Pressing some individual keys does not work.

• Pressing some combination of two keys triggers a third key.

• Pressing some combinations of three keys does not register the third key.

Note

Generated by preprocessing the default keymap which evaluates the LAYOUT macro.

___	K_RIGHT	___	K_PRINT_SCREEN	K_DEL	___	___	___
K_QUOTE	K_ENTER	___	___	K_EQUALS	K_BKSP	K_BRACE_CLOSE	K_BACKSLASH
K_SLASH	K_UP	K_MINUS	K_F12	K_0	K_P	K_BRACE_OPEN	K_SEMICOLON
___	K_LEFT_CTRL	___	___	K_RIGHT_CTRL	___	___	___
___	___	K_F8	K_F9	___	___	___	K_LEFT
K_COMMA	___	K_F7	K_F6	K_F5	K_8	K_I	K_K
K_RIGHT_SHIFT	K_LEFT_SHIFT	___	___	___	___	___	___
K_PERIOD	K_DOWN	___	K_F11	K_F10	K_9	K_O	K_L
K_M	K_N	K_H	K_Y	K_6	K_7	K_U	K_J
K_V	K_B	K_G	K_T	K_5	K_4	K_R	K_F
K_X	K_Z	K_F2	K_F1	K_ESC	K_2	K_W	K_S
K_C	K_SPACE	K_F3	K_F4	K_CAPS	K_3	K_E	K_D
K_RIGHT_ALT	K_LEFT_ALT	___	___	___	___	___	___
___	___	KT_FN	K_TAB	K_TICK	K_1	K_Q	K_A
___	K_LEFT_SUPER	___	___	___	___	___	___
___	___	___	___	___	___	___	___

Pressing One Key Triggers Others

If pressing one key triggers others, and those keys share a row or column, then there is a short among rows or columns.

For example, if pressing N also triggers B, then the rows containing N and B are shorted, so pressing M will trigger V, etc.

Shorts are most likely on the mainboard, probably near the keyboard ribbon connector, but they can also occur near the EC pins or on the keyboard itself.

Pressing Some Individual Keys Does Not Work

If pressing a single key does not register anything, then there is probably a broken connection to the keyboard.

This could be a poorly seated keyboard ribbon connector, damage to the mainboard, or damage to the keyboard itself.

Pressing Some Combinations of Two Keys Triggers a Third Key

If there is a short in the keyboard matrix at a position that does not contain a key, then pressing keys in that row and column at the same time may cause a third key press to register.

For example, if pressing Left Shift + U triggers N as well, there is a short between the row containing Left Shift and the column containing U. (Left Shift, U, N, and the empty cell form a rectangle.)

This happens because the shorted position is normally impossible to press (there is no key there), but it causes a “ghost” with the extra triggered key.

The EC knows there is no key at this position, so it registers the third key press.

Pressing some combinations of three keys does not work

Pressing three keys that form the corners of a rectangle causes a “ghost” press with the fourth corner of the rectangle. If all four of those positions contain keys, it is impossible for the EC to determine which three keys are pressed. It cannot register the third key press.

This behavior is normal. This happens because the three pressed keys complete a circuit between the fourth key’s row/column.

The key matrix is optimized so that this is uncommon — for example, modifier keys have their own rows, so you can press modifier keys with any two other keys without causing a ghost.