PIC18F44J50-I/SPSQTP View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F44J50-I/SPSQTP

28/44-Pin, Low-Power, High-Performance USB Microcontrollers with nanoWatt XLP Technology

Microchip Technology 

PIC18F46J50 FAMILY

26.0 CHARGE TIME

MEASUREMENT UNIT (CTMU)

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

measurement input

• On-chip precision current source

• Four-edge input trigger sources

• Polarity control for each edge source

FIGURE 26-1:

CTMU BLOCK DIAGRAM

• Control of edge sequence

• Control of response to edges

• Time measurement resolution of 1 nanosecond

• High-precision time measurement

• Time delay of external or internal signal

asynchronous to system clock

• Accurate current source suitable for capacitive

measurement

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, Timer1 or Output Compare Module 1.

Figure 26-1 provides a block diagram of the CTMU.

EDGEN

EDGSEQEN

EDG1SEL<1:0>

EDG1POL

EDG2SEL<1:0>

EDG2POL

CTMUCONH:CTMUCONL

CTMUICON

EDG1STAT

EDG2STAT

ITRIM<5:0>

IRNG<1:0>

Current Source

TGEN

IDISSEN

CTED1

CTED2

Timer1

ECCP1

Edge

Control

Logic

Current

Control

CTMU

Control

Logic

A/D Converter Comparator 2

Input

Pulse

Generator

Comparator 2 Output

CTPLS

 2011 Microchip Technology Inc.

DS39931D-page 401

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