PIC18F45K22-I/PT Microchip Technology Inc., PIC18F45K22-I/PT Datasheet - Page 327

• Manufacturer Part Number: PIC18F45K22-I/PT
• Description: 44 TQFP 10x10x1mm TRAY, 32KB, Flash, 1536bytes-RAM, 8-bit Family, nanoWatt XLP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F45K22-I/PT

• A/d Inputs: 28-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 16 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 35
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin TQFP
• Programmable Memory: 32K Bytes
• Ram Size: 1.5K Bytes
• Speed: 64 MHz
• Temperature Range: –40 to 125 °C
• Timers: 3-8-bit, 4-16-bit
• Voltage, Range: 1.8-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

19.5
Time can be precisely measured after the ratio (C/I) is
measured from the current and capacitance calibration
step by following these steps:
1.
2.
3.
4.
5.
FIGURE 19-3:
 2010 Microchip Technology Inc.
Initialize the A/D Converter and the CTMU.
Set EDG1STAT.
Set EDG2STAT.
Perform an A/D conversion.
Calculate the time between edges as T = (C/I) * V,
where I is calculated in the current calibration step
(Section 19.3.1 “Current Source
C is calculated in the capacitance calibration step
(Section 19.3.2 “Capacitance
V is measured by performing the A/D conversion.
Measuring Time with the CTMU
Module
TYPICAL CONNECTIONS AND INTERNAL CONFIGURATION FOR TIME
MEASUREMENT
CTED1
CTED2
AN
R
PR
X
Calibration”) and
Calibration”),
PIC18(L)FXXK22 Device
EDG2
Preliminary
EDG1
C
AD
A/D Converter
Current Source
CTMU
Output Pulse
It is assumed that the time measured is small enough
that the capacitance, C
to the A/D Converter. For the smallest time measure-
ment, always set the A/D Channel Select register
(AD1CHS) to an unused A/D channel; the correspond-
ing pin for which is not connected to any circuit board
trace. This minimizes added stray capacitance, keep-
ing the total circuit capacitance close to that of the A/D
Converter itself (4-5 pF). To measure longer time
intervals, an external capacitor may be connected to an
A/D channel and this channel selected when making a
time measurement.
PIC18(L)F2X/4XK22
OFFSET
, provides a valid voltage
DS41412D-page 327