Datasheet

Device
Keyboardcontroller
kbd_r_0
kbd_c_0
V
CC
Internal
pullup
kbd_r_1
kbd_r_2
kbd_r_3
kbd_r_4
kbd_r_5
kbd_c_1
kbd_c_2
kbd_c_3
kbd_c_4
kbd_c_5
kbd_r_6
kbd_r_7
kbd_c_6
kbd_c_7
8x8
Keyboardmatrix
032-061
TPS65950
SWCS032E–OCTOBER 2008–REVISED JANUARY 2011 www.ti.com
11 Keyboard
11.1 Keyboard Connection
The keyboard is connected to the chip using:
• KBR (7:0) input pins for row lines
• KBC (7:0) output pins for column lines
Figure 11-1 shows the keyboard connection.
Figure 11-1. Keyboard Connection
When a key button of the keyboard matrix is pressed, the corresponding row and column lines are shorted
together. To allow key press detection, all input pins (KBR) are pulled up to V
CC
and all output pins (KBC)
are driven low.
Any action on a button generates an interrupt to the sequencer.
The decoding sequence is written to allow detection of simultaneous press actions on several key buttons.
The keyboard interface can be used with a smaller keyboard area than 8 × 8. To use a 6 × 6 keyboard,
KBR(6) and KBR(7) must be tied high to prevent any scanning process distribution.
130 Keyboard Copyright © 2008–2011, Texas Instruments Incorporated
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