Data Sheet

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MPR121 Sensor

14 Freescale Semiconductor

9. Individual Charge Current Register (0x5F~0x6B)

Bit

Read

CDCx

Write

These registers hold the individual Charge/Discharge Current (CDCx) value for each channel if CDC global value is not used.

The parameter setting is similar to the CDC. The power on reset default of these registers is all zeros.

Field

Description

5:0

CDCx

Individual Charge Discharge Current – The Individual Charge Discharge Current field

selects the supply current to be used when charging and discharging a specific channel.

Programmable in 1uA step.

000000 Encoding 0 – Global CDC is used if this channel is enabled (Default).

000001 Encoding 1 – Sets the current to 1μA, global CDC is not used

010000 Encoding 16 – Sets the current to 16μA, global CDC is not used

111111 Encoding 63 – Sets the current to 63μA, global CDC is not used

If the CDCx is zero, then the global value is used. If there is none zero data in 0x5F~0x6B, then the individual value will be

used for this respective channel instead of the global CDC value.

If auto configuration is enabled and run once, the individual CDC will be automatically updated by MPR121 internally after auto

configuration is finished.

10. Individual Charge Time Register (0x6C~0x72)

Bit

Read

CDTx’

CDTx

Write

These registers hold the individual Charge/Discharge Time (CDTx) value for each channel if CDT global value is not used. The

parameter setting is similar to the CDT. The power on reset default of these registers is all zeros.

Field

Description

7:5

CDTx

Individual Charge Discharge Time – selects the amount of charge time for individual

channels. Programmable to 0.5 (2

n-1

) uS

000 Encoding 0 – Global CDT is used if this channel is enabled (Default)

001 Encoding 1 – Time is set to 0.5μs, global CDT is not used

010 Encoding 2 – Time is set to 1μs, global CDT is not used

111 Encoding 7 – Time is set to 32μs, global CDT is not used

If the CDTx is zero, then the global value is used. If there is none zero data in 0x6C~0x72, then the individual value will be

used for this respective channel instead of the global CDT value.

If auto configuration and SCTS bit in Auto Configuration Register 1 (0x7B) are enabled and run once, the individual CDTx will

be automatically updated by MPR121 internally after auto configuration is finished.