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5. Device Operation

KeyWarrior24 registers as a standard HID

keyboard and supports boot protocol. It does not

need any special drivers to be installed, standard

system drivers are sufficient.

The country code is 0 for not localized hardware,

which allows to use a single version of the chip for

all international keyboard layouts. Usage codes are

defined for 0 to 164, which include the Power key

and the = sign in the keypad, as well as the

compose keys for Asian languages and several

special keys that may or may not be supported by

individual operating systems.

In addition the media control keys Mute, Play/

Pause, Eject, Fast Forward, Fast Backward,

5.1 Power Up

Every time the supply voltage is applied

KeyWarrior24 executes an internal reset sequence.

All internal pull up resistors are disabled upon

power up and will be activated during the internal

reset sequence.

5.2 Keyboard Scanning

KeyWarrior24 scans the keyboard matrix every

scan

by sequentially pulling one of the Y lines low

and then reading the status at the X lines. When the

scan matrix changes status and then remains stable

for t

debounce

KeyWarrior24 decodes the changes

and generates scancodes.

On KeyWarrior24-S3 the nine direct connected

keys are checked every t

scan

and are decoded after

remaining stable for t

debounce

5.2.1 Encoder scanning

KeyWarrior24-S3 scans the encoder inputs at the

highest rate possible. The actual rate depends on

several parameters and is not static.

The encoder inputs are not debounced. It is not

recommended to use mechanical encoders without

an external debouncing circuit. Key strokes are

generated immediately upon detecting the rising

edge on the A signal from an encoder when in Full

mode, in quadrant mode a key is generated on

every edge on A or B.

5.3 Key Rollover

KeyWarrior supports true n-key rollover. All keys

in the matrix may be pressed at the same time

without KeyWarrior missing any code. However

due to the phantom key effect it can not be

guaranteed that combinations of many keys are

properly reported (see 5.3.1).

USB has a limitation on how many keys can be

reported at the same time. On USB any six keys

plus all eight modifiers (GUI, Ctrl, Alt, Shift) may

be pressed at the same time. If more than six

ordinary keys are pressed an error state is reported.

So USB has a 6-key plus modifiers rollover.

5.3.1 Phantom Keys

Phantom keys do occur when three or more keys in

a keyboard matrix are pressed in a combination

that leads to the matrix reading like a fourth key

has been pressed.

To avoid phantom keys diodes may be added to the

keys. If diodes are used they have to be put in

series with the key switches. The kathodes have to

be connected to the Y lines and anodes to X lines.

It is highly recommended to place all modifier

keys on a single row or column and put diodes on

all of them.

5.4 Custom Scancode Tables

The standard KeyWarrior24 has a fixed key table

that is factory programmed. For production

volumes it is possible to order KeyWarrior24 with

an individual key layout.

KeyWarrior uses a single table to translate the

matrix coordinates to USB usage codes. This table

is called the "Master Translation Table".

For information on generating the Master

Translation Table please refer to the document

"Creating Custom KeyWarrior Scancode Tables".

5.5 Function Shift Keys

KeyWarrior24 allows the definition of two function

shift keys. If one of these keys is pressed

KeyWarrior uses a second or third translation table

to convert matrix coordinates to USB usage codes.

This allows a small keyboard to generate all

functions of a full sized keyboard.

The function shift key may be on any coordinate in

the matrix, it is assigned by placing a special code

in the corresponding table position.

V 1.1.2, December 2nd 2013, for chip revision 1.1.1.4/1.1.1.B and up