TCA8418E_15 Datasheet, PDF (40/50 Pages) Texas Instruments – I2C Controlled Keypad Scan IC With Integrated ESD Protection

TCA8418E
SCPS222C – MAY 2010 – REVISED OCTOBER 2015
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The schematic for this keypad layout is shown in Figure 33, with the key event table values. Note that no
external pullup resistors are needed, because the TCA8418E has integrated pullup resistors.
1
2
3
ROW0
11
12
13
ROW1
21
22
23
ROW2
31
32
33
ROW3
COL0
COL1
Figure 33. Keypad Schematic
COL2
9.2.2.2 Configuring the Registers
The next step to design a keypad array for the TCA8418E is to configure the appropriate hardware registers.
The registers that will need to be modified for the desired features are the following:
STEP
Setup keypad array
Setup Interrupts
Setup Unlock Key Combination
Set Keypad Lock Timers
Table 27. Registers to Modify
REGISTER TO EDIT
VALUE TO WRITE
KP_GPIO1 (0x1D)
0x0F
KP_GPIO2 (0x1E)
KP_GPIO3 (0x1F)
0x07
0x00
CFG (0x01)
0x95
UNLOCK1 (0x0F)
UNLOCK2 (0x10)
0x21
0x01
KP_LCK_TIMER (0x0E)
0x52
DESCRIPTION
Set ROW0-ROW3 to KP
Matrix
Set COL0-COL2 to KP
Matrix
Set COL8-COL9 to GPIO
Set the KE_IEN,
K_LCK_IEN, INT_CFG,
and AI bits
Set first unlock key to key
33
Set second unlock key to
key 1
Lock1 to Lock2 set to 2
seconds. Interrupt mask
timer set to 10 seconds
40
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