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PIC24F Family Reference Manual
DS39724B-page 11-2 © 2010 Microchip Technology Inc.
11.1 INTRODUCTION
The Charge Time Measurement Unit (CTMU) is a flexible analog module that provides accurate
differential time measurement between pulse sources, as well as asynchronous pulse genera-
tion. 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 16 channels available for capacitive or time measurement input
On-chip precision current source
Four-edge input trigger sources
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 asynchronous to system clock
The CTMU works in conjunction with the A/D Converter to provide up to 16 channels for time or
charge measurement, depending on the specific device and the number of A/D channels avail-
able. When configured 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. For device-specific information on available input sources,
refer to the appropriate PIC24F data sheet.
A block diagram of the CTMU is shown in Figure 11-1.
Note: This family reference manual section is meant to serve as a complement to device
data sheets. Depending on the device variant, this manual section may not apply
to all PIC24F devices.
Please consult the note at the beginning of the Charge Time Measurement Unit
(CTMU) chapter in the current device data sheet to check whether this document
supports the device you are using.
Device data sheets and family reference manual sections are available for
download from the Microchip Worldwide Web site at: http://www.microchip.com
Protego_Release_01_05-Related-OEM-Documentation-PIC24FJ32MC10X-Reference_Manual-Section11-Charge_Time_Measurement_Unit.pdf