Datasheet

 2013-2014 Microchip Technology Inc. DS70000689D-page 321
dsPIC33EPXXXGM3XX/6XX/7XX
22.0 CHARGE TIME
MEASUREMENT UNIT (CTMU)
The Charge Time Measurement Unit is a flexible analog
module that provides accurate differential time measure-
ment between pulse sources, as well as asynchronous
pulse generation. Its key features include:
• Four edge input trigger sources
• Polarity control for each edge source
• Control of edge sequence
• Control of response to edges
• Precise time measurement resolution of 1 ns
• Accurate current source suitable for capacitive
measurement
• On-chip temperature measurement using a
built-in diode
Together with other on-chip analog modules, the CTMU
can be used to precisely measure time, measure
capacitance, measure relative changes in capacitance
or generate output pulses that are independent of the
system clock.
The CTMU module is ideal for interfacing with
capacitive-based sensors. The CTMU is controlled
through three registers: CTMUCON1, CTMUCON2
and CTMUICON. CTMUCON1 and CTMUCON2
enable the module and control edge source selection,
edge source polarity selection and edge sequencing.
The CTMUICON register controls the selection and
trim of the current source.
Note 1: This data sheet summarizes the features
of the dsPIC33EPXXXGM3XX/6XX/7XX
family of devices. It is not intended to be
a comprehensive reference source. To
complement the information in this data
sheet, refer to the “dsPIC33/PIC24 Fam-
ily Reference Manual”, “Charge Time
Measurement Unit (CTMU)” (DS70661),
which is available on the Microchip web
site (www.microchip.com).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.