Rainbow Electronics AT77C105A - Manual (Page 20)

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AT77C105A [Preliminary]
5419A–BIOM–01/05
Navigation Register
Register Name: Navigation (3 x 8 bits)
Access Type: Read Only (these three registers cannot be read individually. The read-
ing command of the first navigation register [address 0b1000] returns the value of the
three registers).
Function: The format of the navigation registers is similar to the PS/2 protocol. Three
registers are used to codemovements and clicks. The navigation registers are initialized
after each reading. The registers only represent actions (movement, click, transition...)
that have occurred since the last data packet sent to thehost.
General Register
• YOVR: Y overflow
0: default
1: Y movement overflow
High (‘1’) when the Y movement counter is overflowed.
• XOVR: X overflow
0: default
1: X movement overflow
High (‘1’) when the X movement counter is overflowed.
• YSIGN: Y sign bit
0: default, positive Y movement
1: negative Y movement
High (‘1’) when the Y movement is negative. Low when the Y movement is positive.
• XSIGN: X sign bit
0: default, positive X movement
1: negative X movement
High (‘1’) when the X movement is negative. Low when the X movement is positive.
• TRANS: Not used, for test purposes only.
• CLICK: Click
0: default
1: click detected
This function is not in the PS/2 protocol.
• FINGER: Not used, for test purposes only.
b7 b6 b5 b4 b3 b2 b1 b0
YOVR XOVR YSIGN XSIGN 1 TRANS CLICK FINGER
0 0 0 0 1 0 0 0