Data Sheet

MPR121 Sensor
2 Freescale Semiconductor
PIN DESCRIPTION
Pin No.
Pin Name
Description
1
IRQ
Active Low Open-drain Interrupt Output
2
SCL
I
2
C Serial Clock
3
SDA
I
2
C Serial Data
4
ADDR
I²C Slave Address Pin Selects.
Connect to VSS, VDD, SDA, SCL to choose address 0x5A, 0x5B, 0x5C, 0x5D respectively.
5
VREG
Internal Supply Voltage.
Internal regulator output. Bypass to VSS with a 0.1 μF capacitor. Connect to VDD when supply below 2.75V
6
VSS
Ground
7
REXT
Reference Resistor Connection.
VSS
8
ELE0
Electrode 0 Connection
9
ELE1
Electrode 1 Connection
10
ELE2
Electrode 2 Connection
11
ELE3
Electrode 3 Connection
12
ELE4/LED0
Electrode 4, or LED0, or GPIO4 Connection
13
ELE5/LED1
Electrode 5, or LED1, or GPIO5 Connection
14
ELE6/LED2
Electrode 6, or LED2, or GPIO6 Connection
15
ELE7/LED3
Electrode 7, or LED3, or GPIO7 Connection
16
ELE8/LED4
Electrode 8, or LED4, or GPIO8 Connection
17
ELE9/LED5
Electrode 9, or LED5, or GPIO9 Connection
18
ELE10/LED6
Electrode 10, or LED6, or GPIO10 Connection
19
ELE11/LED7
Electrode 11, or LED7, or GPIO11 Connection
20
VDD
Power Supply Input.
Bypass to VSS by a 0.1 μF capacitor.
TYPICAL APPLICATION EXAMPLE AND ELECTRODE PATTERN
(a)
(c) (d) (b)
Figure 1. (a) Typical application circuit
(b) Button matrix pattern using 12 channels for 20 touch buttons
(c) Slide wheel and slide bar pattern using 10 channels
(d) Touchpad 5x7 pattern using 12 channels