User manual

Code Mercenaries

4.2.5 Switch Matrix Mode Pins

IO-Warrior56 supports scanning of a 8x8 matrix of

keys or switches. When this function is enabled

P0.0..7 will turn off their internal pull up resistors

and will be used as the Y lines that are periodically

driven to Gnd voltage level. P2.0..7 will serve as

the X matrix inputs, they will keep their internal

pull up resistors active so a closed switch in the

matrix will pull down the X line when the

corresponding Y line is driven low.

To allow more than two switches to be closed at

the same time and still be able to faultlessly detect

which of the matrix points are closed it is

necessary to insert a diode in series with every key

or switch in the matrix. The kathodes of the diodes

have to be connected to the Y lines (P0.0..7).

The following pins get reassigned when the key

mode is enabled:

The matrix is scanned every 4msec. Debounce

time is 16msec.

When IO-Warrior enters the suspend mode the X

and Y lines will be pulled high by internal pull up

resistors. Closing a switch/key does not wake the

IO-Warrior.

Function IOW56

P2.0

P2.1

P2.2

P2.3

P2.4

P2.5

P2.6

P2.7

P0.0

P0.1

P0.2

P0.3

P0.4

P0.5

P0.6

P0.7

V 1.0.3, November 6nd 2012 for chip version V1.1.0.1