Rainbow Electronics AT77C104B - Manual (Page 16)

16
AT77C104B
5347B–BIOM–08/04
Notes: 1. Navfreq and Navv registers should not be changed once the navigation mode is
selected. Finger sensitivity refers to the minimum level of information required from a
finger. The sensitivity is linked to the integration time; a longer integration time
enables better sensitivity but does not tolerate fast movement.
2. The navigation frequency is the frequency needed for the reading of one new naviga-
tion frame.
3. The Clickv register should not be changed once the click mode is selected.
Clickctrl Register Register Name:Clickctrl (7 bits)
Access Type:Read/Write
Function:Click control
• CLICKFREQ: click pixels reading frequency
00: 180 Hz
01: 90 Hz (default value)
10: 60 Hz
11: 45 Hz
Faster frequency enables faster finger click detection. Lower frequency enables higher
sensitivity.
• CLICKDET: threshold for selecting the black/white color of a slice
00: more than 7 black/white pixels and less than 5 white/black pixels
01: more than 8 black/white pixels and less than 4 white/black pixels
10: more than 9 black/white pixels and less than 3 white/black pixels
11: more than 10 black/white pixels and less than 2 white/black pixels
• CLICKCPT: click detection counter (maximum number of slices read between
two transitions)
000: 5
001: 7
010: 10
011: 12
100: 16
101: 20
110: 25
111: 31
Two transitions are interpreted as a click if the number of slices between them is less
than CLICKCPT. This is used to differentiate a touch-down/touch-up from a real click. A
click is equivalent to two close touch-down/touch-up transitions.
b6 b5 b4 b3 b2 b1 b0
CLICKFREQ
(MSB)
CLICKFREQ
(LSB)
CLICKDET
(MSB)
CLICKDET
(LSB)
CLICKCPT
(MSB)
CLICKCPT CLICKCPT
(LSB)
0 1 0 1 1 0 1