PIC32MX1XX Datasheet, PDF (217/320 Pages) Microchip Technology – 32-bit Microcontrollers (up to 128 KB Flash and 32 KB SRAM) with Audio and Graphics Interfaces, USB, and Advanced Analog

PIC32MX1XX/2XX
24.0 CHARGE TIME
MEASUREMENT UNIT (CTMU)
Note 1: This data sheet summarizes the fea-
tures of the PIC32MX1XX/2XX family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to Section 37. “Charge
Time Measurement Unit (CTMU)”
(DS61167) in the “PIC32 Family
Reference Manual”, which is available
from 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.
The Charge Time Measurement Unit (CTMU) is a flex-
ible analog module that has a configurable current
source with a digital configuration circuit built around it.
The CTMU can be used for differential time measure-
ment between pulse sources and can be used for gen-
erating an asynchronous pulse. By working with other
on-chip analog modules, the CTMU can be used for
high resolution time measurement, measure capaci-
tance, measure relative changes in capacitance or
generate output pulses with a specific time delay. The
CTMU is ideal for interfacing with capacitive-based
sensors.
The module includes the following key features:
• Up to 13 channels available for capacitive or time
measurement input
• On-chip precision current source
• 16-edge input trigger sources
• Selection of edge or level-sensitive inputs
• Polarity control for each edge source
• Control of edge sequence
• Control of response to edges
• High precision time measurement
• Time delay of external or internal signal asynchro-
nous to system clock
• Integrated temperature sensing diode
• Control of current source during auto-sampling
• Four current source ranges
• Time measurement resolution of one nanosecond
A block diagram of the CTMU is shown in Figure 24-1.
FIGURE 24-1:
CTED1
•
•
•
CTED13
Timer1
OC1
IC1-IC3
CMP1-CMP3
PBCLK
CTMU BLOCK DIAGRAM
CTMUCON1 or CTMUCON2
CTMUICON
ITRIM<5:0>
IRNG<1:0>
Current Source
Edge
Control
Logic
EDG1STAT
EDG2STAT
Current
Control
TGEN
CTMU
Control
Logic
CTMUT
(To ADC)
Temperature
Sensor
CTMUP
CTMUI
(To ADC S&H capacitor)
C2INB
Pulse
Generator
CDelay
External capacitor
for pulse generation
Comparator 2
ADC
Trigger
CTPLS
Current Control Selection
CTMUT
CTMUI
CTMUP
No Connect
TGEN
0
0
1
1
EDG1STAT, EDG2STAT
EDG1STAT = EDG2STAT
EDG1STAT ≠ EDG2STAT
EDG1STAT ≠ EDG2STAT
EDG1STAT = EDG2STAT
© 2011-2012 Microchip Technology Inc.
Preliminary
DS61168D-page 217