Nordic 3 - Keypad Matrix

5 Hardware description: Smart Remote 3 DK add-on
Doc. ID 4374_139 v1.1
Page 31
Pin Label Description
5 I2C_DATA_TP Two-wire serial data
6 3V3 Power supply for trackpad
The trackpad requires a stable 3.3 V supply (see Figure 24: Voltage regulator for the trackpad on page 36
for details). Because of this the signals going from the nRF device to the trackpad needs to be level shifted. See
the figure below:
R28
N.C.
R30
4k7
3V3
I2C_DATA
I2C_CLK
I2C_DATA
R27
N.C.
R29
4k7
3V3
I2C_CLK
I2C_CLK_TP
I2C_DATA_TP
WU_IRQ_TP
WU_IRQ
3V3
R32
N.C.
C50
100nF
C51
100nF
R35
N.C.
3V3
N.C.
Q4
BC847C
R33
N.C.
N.C.
Q5
BC847C
R34
N.C.
3V3
VCCA
1
GND
4
A0
2
A1
3
OE
5
B1
6
B0
7
VCCB
8
U8
FXMA2102
VCC
VCC
VCC
VCC
SB38
Figure 17: Level translation circuit for the trackpad
5.3.2 Keypad matrix
The keypad on the Smart Remote 3 DK add-on board (PCA63519) board has 39 buttons.
The matrix has six rows and eight columns that gives room for 48 buttons in firmware, of which 39 are used by
the keypad, and one row is used for two push buttons that function as left and right mouse buttons. A total of
41 of 48 locations are in use. See Figure 18: Keypad matrix on page 32.