Data Sheet

MPR121 Sensor
10 Freescale Semiconductor
Table 1. Register Map
REGISTER
Fields
Register
Address
Initial
Value
Auto
Increment
Address
ELE3 Electrode Current
CDC3
0x62
0x00
Register
Address + 1
ELE4 Electrode Current
CDC4
0x63
0x00
ELE5 Electrode Current
CDC5
0x64
0x00
ELE6 Electrode Current
CDC6
0x65
0x00
ELE7 Electrode Current
CDC7
0x66
0x00
ELE8 Electrode Current
CDC8
0x67
0x00
ELE9 Electrode Current
CDC9
0x68
0x00
ELE10 Electrode Current
CDC10
0x69
0x00
ELE11 Electrode Current
CDC11
0x6A
0x00
ELEPROX Electrode Current
CDC12
0x6B
0x00
ELE0, ELE1 Charge Time
CDT1
CDT0
0x6C
0x00
ELE2, ELE3 Charge Time
CDT3
CDT2
0x6D
0x00
ELE4, ELE5 Charge Time
CDT5
CDT4
0x6E
0x00
ELE6, ELE7 Charge Time
CDT7
CDT6
0x6F
0x00
ELE8, ELE9 Charge Time
CDT9
CDT8
0x70
0x00
ELE10, ELE11 Charge Time
CDT11
CDT10
0x71
0x00
ELEPROX Charge Time
CDT12
0x72
0x00
GPIO Control Register 0
CTL0
0x73
0x00
GPIO Control Register 1
CTL1
0x74
0x00
GPIO Data Register
DAT
0x75
0x00
GPIO Direction Control Register
DIR
0x76
0x00
GPIO Enable Register
EN
0x77
0x00
GPIO Data Set Register
SET
0x78
0x00
GPIO Data Clear Register
CLR
0x79
0x00
GPIO Data Toggle Register
TOG
0x7A
0x00
AUTO-CONFIG Control Register 0
AFES
RETRY
BVA
ARE
ACE
0x7B
0x00
AUTO-CONFIG Control Register 1
SCTS
OORIE
ARFIE
ACFIE
0x7C
0x00
AUTO-CONFIG USL Register
USL
0x7D
0x00
AUTO-CONFIG LSL Register
LSL
0x7E
0x00
AUTO-CONFIG Target Level Register
TL
0x7F
0x00
0x00
Soft Reset Register
SRST
0x80
0x00
-
Factory Reserved Region(0x81~0xFF)
-
-
-
-
Register Operation
1. General Rules
Note: After completing power on reset (POR) or soft reset by command, MPR121 all registers are in default reset initial value
(see Table 1). All the registers are cleared, except AFE Configuration Registers 0x5C (Default 0x10) and 0x5D (Default 0x24).
MPR121 reset default mode is Stop Mode without any capacitance measurement. Set MPR121 into Run Mode by configuring
ECR register (0x5E) so that least one of the 13 measurement channels is enabled. Set MPR121 into Stop Mode by writing
2bXX000000 to ECR register at any time. For all the registers, the current value can be read at any time.
Note: Registers write operation can only be done after MPR121 is set into Stop Mode, except the ECR and GPIO/LED related
registers, which means changing the value of these registers while MPR121 is in Run Mode will not be effective.
Registers from address 0x00 to 0x2A are the output registers which are updated periodically when MPR121 is in Run Mode.
While Baseline Value Registers 0x1D to 0x2A are the internal output baseline registers, these registers are also writeable to
user, this is useful if customer setting targets as the initial baseline tracking start points is desired.
Registers from address 0x2B to 0x7F are control and configuration registers, which need to be correctly configured and
initialized to start the capacitance measurement and touch detection.