Figure 33 Autorepeat

Scan code placed in buffer Auto repeat delay w—w r i i T

Auto repeat start delay

By also telling you how long the key has been pressed, your application can speed up the process of incrementing or decrementing the value of a parameter based on how long the key has been pressed.

To reduce the recurring cost of your system, you can assign multiple functions to each key. To access the alternate function of each key, you can either assign a prefix key (like calculators) or provide one or more Shift keys. With a prefix key, you access the alternate function by pressing the prefix key followed by the desired key. To execute another alternate function, you generally have to press the prefix key again. With a Shift key, you access the alternate function by first pressing and holding down the Shift key and then pressing the desired key. In both cases, the keyboard scanning code can keep track of the operation and provide your application with a unique scan code for each type of key pressed. The matrix f j Key RELEASED

keyboard module supports the second method and allows you to have up to three Shift keys. Note that you can still use the prefix keys with the keyboard module except that your user interface software will have to keep track of them.

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