PIC18F25J11-I/PT MICROCHIP [Microchip Technology], PIC18F25J11-I/PT Datasheet - Page 373

• Manufacturer Part Number: PIC18F25J11-I/PT
• Description: 28/44-Pin, Low-Power, High-Performance Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

24.0
The Charge Time Measurement Unit (CTMU) is a
flexible analog module that provides accurate differen-
tial time measurement between pulse sources, as well
as asynchronous pulse generation. By working 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 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
• On-chip precision current source
• Four-edge input trigger sources
• Polarity control for each edge source
• Control of edge sequence
FIGURE 24-1:
© 2009 Microchip Technology Inc.
measurement input
CHARGE TIME
MEASUREMENT UNIT (CTMU)
CTEDG1
CTEDG2
ECCP2
ECCP1
CTMU BLOCK DIAGRAM
EDGEN
EDGSEQEN
EDG1SELx
EDG1POL
EDG2SELx
EDG2POL
Control
Logic
Edge
EDG1STAT
EDG2STAT
A/D Converter
Current Source
CTMUICON
CTMUCON
Current
Control
PIC18F46J11 FAMILY
Comparator 2
• Control of response to edges
• Time measurement resolution of 1 nanosecond
• High precision time measurement
• Time delay of external or internal signal
• Accurate current source suitable for capacitive
The CTMU works in conjunction with the A/D Converter
to provide up to 13 channels for time or charge
measurement, depending on the specific device and
the number of A/D channels available. When config-
ured for time delay, the CTMU is connected to one of
the analog comparators. The level-sensitive input edge
sources can be selected from four sources: two
external inputs or ECCP1/ECCP2 Special Event
Triggers.
Figure 24-1 provides a block diagram of the CTMU.
Input
ITRIM<5:0>
IRNG<1:0>
asynchronous to system clock
measurement
Comparator 2 Output
Generator
Control
CTMU
Pulse
Logic
TGEN
IDISSEN
DS39932C-page 373
CTPLS