PIC18F87J90-I/PT Microchip Technology, PIC18F87J90-I/PT Datasheet - Page 317
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PIC18F87J90-I/PT
Manufacturer Part Number
PIC18F87J90-I/PT
Description
IC PIC MCU FLASH 128KB 80-TQFP
Manufacturer
Microchip Technology
Series
PIC® 18Fr
Datasheets
1.PIC18F67J90-IPT.pdf
(450 pages)
2.PIC18F67J90-IPT.pdf
(3 pages)
3.PIC18F67J90-IPT.pdf
(10 pages)
4.PIC18F66J90-IPT.pdf
(444 pages)
Specifications of PIC18F87J90-I/PT
Program Memory Type
FLASH
Program Memory Size
128KB (64K x 16)
Package / Case
80-TFQFP
Core Processor
PIC
Core Size
8-Bit
Speed
48MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, LCD, LVD, POR, PWM, WDT
Number Of I /o
67
Ram Size
3.8K x 8
Voltage - Supply (vcc/vdd)
2 V ~ 3.6 V
Data Converters
A/D 12x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Processor Series
PIC18F
Core
PIC
Data Bus Width
8 bit
Data Ram Size
3923 B
Interface Type
AUSART, EUSART, I2C, SPI
Maximum Clock Frequency
48 MHz
Number Of Programmable I/os
67
Number Of Timers
4
Operating Supply Voltage
2.65 V to 3.6 V
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
3rd Party Development Tools
52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
Minimum Operating Temperature
- 40 C
On-chip Adc
10 bit, 12 Channel
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
For Use With
AC162079 - HEADER MPLAB ICD2 18F85J90 64/80AC164323 - MODULE SKT FOR 100TQFP
Eeprom Size
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Available stocks
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Part Number
Manufacturer
Quantity
Price
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Part Number:
PIC18F87J90-I/PT
Manufacturer:
MICROCHIP
Quantity:
4 000
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Part Number:
PIC18F87J90-I/PT
Manufacturer:
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Quantity:
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24.4
There are two separate methods of measuring capaci-
tance with the CTMU. The first is the absolute method,
in which the actual capacitance value is desired. The
second is the relative method, in which the actual
capacitance is not needed, rather an indication of a
change in capacitance is required.
24.4.1
For absolute capacitance measurements, both the
current and capacitance calibration steps found in
Section 24.3 “Calibrating the CTMU Module” should
be followed. Capacitance measurements are then
performed using the following steps:
1.
2.
3.
4.
5.
6.
7.
8.
2010 Microchip Technology Inc.
Initialize the A/D Converter.
Initialize the CTMU.
Set EDG1STAT.
Wait for a fixed delay, T.
Clear EDG1STAT.
Perform an A/D conversion.
Calculate the total capacitance, C
where I is known from the current source
measurement step (Section 24.3.1 “Current
Source Calibration”), T is a fixed delay and V is
measured by performing an A/D conversion.
Subtract the stray and A/D capacitance
(C
Calibration”) from C
measured capacitance.
OFFSET
Measuring Capacitance with the
CTMU
ABSOLUTE CAPACITANCE
MEASUREMENT
from Section 24.3.2 “Capacitance
TOTAL
to determine the
TOTAL
= (I * T)/V,
PIC18F87J90 FAMILY
24.4.2
An application may not require precise capacitance
measurements. For example, when detecting a valid
press of a capacitance-based switch, detecting a relative
change of capacitance is of interest. In this type of appli-
cation, when the switch is open (or not touched), the total
capacitance is the capacitance of the combination of the
board traces, the A/D Converter, etc. A larger voltage will
be measured by the A/D Converter. When the switch is
closed (or is touched), the total capacitance is larger due
to the addition of the capacitance of the human body to
the above listed capacitances and a smaller voltage will
be measured by the A/D Converter.
Detecting capacitance changes is easily accomplished
with the CTMU using these steps:
1.
2.
3.
4.
5.
The voltage measured by performing the A/D conver-
sion is an indication of the relative capacitance. Note
that in this case, no calibration of the current source or
circuit capacitance measurement is needed. See
Example 24-4 for a sample software routine for a
capacitive touch switch.
Initialize the A/D Converter and the CTMU.
Set EDG1STAT.
Wait for a fixed delay.
Clear EDG1STAT.
Perform an A/D conversion.
RELATIVE CHARGE
MEASUREMENT
DS39933D-page 317
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