PIC24FJ64GA110-E/PT Microchip Technology, PIC24FJ64GA110-E/PT Datasheet - Page 241

• Manufacturer Part Number: PIC24FJ64GA110-E/PT
• Description: 16-bit, 16 MIPS, 64KB Flash, 16Kb RAM, 84 I/O, NanoWatt 100 TQFP 12x12x1mm TRAY
• Manufacturer: Microchip Technology
• Series: PIC® 24Fr

Specifications of PIC24FJ64GA110-E/PT

• Core Processor: PIC
• Core Size: 16-Bit
• Speed: 32MHz
• Connectivity: I²C, IrDA, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 85
• Program Memory Size: 64KB (22K x 24)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 3.6 V
• Data Converters: A/D 16x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: *
• Processor Series: PIC24FJ256GA110
• Core: PIC
• Data Bus Width: 16 bit
• Data Ram Size: 16 KB
• Interface Type: UART, I2C, SPI
• Maximum Clock Frequency: 8 MHz
• Number Of Timers: 5
• Operating Supply Voltage: 3.6 V
• Maximum Operating Temperature: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

24.0
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
• Time measurement resolution of 1 nanosecond
• Accurate current source suitable for capacitive
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 two registers:
CTMUCON and CTMUICON. CTMUCON enables the
module and controls edge source selection, edge
source polarity selection, and edge sequencing. The
CTMUICON register controls the selection and trim of
the current source.
FIGURE 24-1:
 2010 Microchip Technology Inc.
Note:
measurement
CHARGE TIME
MEASUREMENT UNIT (CTMU)
This data sheet summarizes the features
of this group of PIC24F devices. It is not
intended
reference source. For more information,
refer to the “PIC24F Family Reference
Manual”, Section 11. “Charge Time
Measurement Unit (CTMU)” (DS39724).
C
APP
TYPICAL CONNECTIONS AND INTERNAL CONFIGURATION FOR
CAPACITANCE MEASUREMENT
to
be
ANx
AN
R
PR
a
Y
comprehensive
PIC24FJ256GA110 FAMILY
EDG2
EDG1
PIC24FJ Device
A/D Converter
Timer1
CTMU
Current Source
Output Pulse
24.1
The CTMU module measures capacitance by generat-
ing an output pulse, with a width equal to the time,
between edge events on two separate input channels.
The pulse edge events to both input channels can be
selected from four sources: two internal peripheral
modules (OC1 and Timer1) and two external pins
(CTEDG1 and CTEDG2). This pulse is used with the
module’s precision current source to calculate
capacitance according to the relationship
For capacitance measurements, the A/D Converter
samples an external capacitor (C
input channels after the CTMU output’s pulse. A Preci-
sion Resistor (R
on a second A/D channel. After the pulse ends, the
converter determines the voltage on the capacitor. The
actual calculation of capacitance is performed in
software by the application.
Figure 24-1
capacitance measurements, and how the CTMU and
A/D modules are related in this application. This
example also shows the edge events coming from
Timer1, but other configurations using external edge
sources are possible. A detailed discussion on measur-
ing capacitance and time with the CTMU module is
provided in the “PIC24F Family Reference Manual”.
Measuring Capacitance
shows the external connections used for
PR
) provides current source calibration
I = C •
dV
dT
APP
DS39905E-page 241
) on one of its