PIC18F26K80-E/SP Microchip Technology Inc., PIC18F26K80-E/SP Datasheet - Page 254

• Manufacturer Part Number: PIC18F26K80-E/SP
• Description: 28 SPDIP .300IN TUBE, ECAN, 64KB FLASH, 4KB RAM, 16 MIPS, 12-BIT ADC, CTMU
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F26K80-E/SP

• A/d Inputs: 8-Channel, 12-Bit
• Comparators: 2
• Cpu Speed: 16 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 24
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 64K Bytes
• Ram Size: 3.6K Bytes
• Speed: 64 MHz
• Temperature Range: –40 to 125 °C
• Timers: 2-8-bit, 3-16-bit
• Voltage, Range: 1.8-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part

PIC18F66K80 FAMILY
18.6
Time can be precisely measured after the ratio ( C/I ) is
measured from the current and capacitance calibration
step. To do that:
1.
2.
3.
4.
5.
FIGURE 18-3:
DS39977C-page 254
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
• C is calculated in the capacitance calibra-
• V is measured by performing the A/D conversion
step ( Section 18.4.1 “Current Source
Calibration” )
tion step ( Section 18.4.2 “Capacitance
Calibration” )
Measuring Time with the CTMU
Module
TYPICAL CONNECTIONS AND INTERNAL CONFIGURATION FOR TIME
MEASUREMENT
CTED1
CTED2
AN
C
EXT
X
Preliminary
EDG2
EDG1
It is assumed that the time measured is small enough
that the capacitance, C
voltage to the A/D Converter. For the smallest time
measurement, always set the A/D Channel Select bits
CHS<4:0> (ADCON0<6:2>) to an unused A/D channel,
the corresponding pin for which is not connected to any
circuit board trace. This minimizes added stray capaci-
tance, keeping the total circuit capacitance close to that
of the A/D Converter itself (25 pF).
To measure longer time intervals, an external capacitor
may be connected to an A/D channel and that channel
selected whenever making a time measurement.
C
AD
A/D Converter
PIC18F66K80
Current Source
CTMU
A/D Voltage
 2011 Microchip Technology Inc.
AD
+ C
EXT
, provides a valid