PIC16F1938_13 Datasheet, PDF (318/488 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver

PIC16(L)F1938/9
26.4 Current Ranges
The capacitive sensing oscillator can operate within
several different current ranges, depending on the volt-
age reference mode and current range selections.
Within each of the two voltage reference modes there
are four current ranges.
Selection between the voltage reference modes is con-
trolled by the CPSRM bit of the CPSCON0 register.
Clearing this bit selects the fixed voltage references
provided by the capacitive sensing oscillator module.
Setting this bit selects the variable voltage references
supplied by the Fixed Voltage reference (FVR) module
and the Digital-to-Analog Converter (DAC) module.
See Section 26.3 “Voltage Reference Modes” for
more information on configuring the voltage refer-
ences.
Selecting the current range within each voltage reference
mode is controlled by configuring the CPSRNG<1:0> bits
in the CPSCON0 register. See Table 26-1 for proper
current mode selection.
The Noise Detection mode is unique in that it disables
the constant current source associated with the
selected input pin, but leaves the rest of the oscillator
circuitry and pin structure active. This eliminates the
oscillation frequency on the analog pin and greatly
reduces the current consumed by the oscillator mod-
ule.
When noise is introduced onto the pin, the oscillator is
driven at the frequency determined by the noise. This
produces a detectable signal at the comparator stage,
indicating the presence of activity on the pin.
Figure 26-2 shows a more detailed drawing of the
constant current sources and comparators associated
with the oscillator and input pin.
TABLE 26-1: CURRENT RANGE SELECTION
CPSRM
Voltage Reference
Mode
CPSRNG<1:0>
Current Range⁽¹⁾
Note 1:
00
Off
0
Fixed
01
10
Low
Medium
11
High
00
Noise Detection
1
Variable
01
10
Low
Medium
11
High
See Power-Down Currents (IPD) in Section 30.0 “Electrical Specifications” for more information.
DS40001574C-page 318
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