PIC18F87K22-I/PTRSL Microchip Technology Inc., PIC18F87K22-I/PTRSL Datasheet - Page 70

• Manufacturer Part Number: PIC18F87K22-I/PTRSL
• Description: 128kB Flash, 4kB RAM, 1kB EE, nanoWatt XLP, GP, 80 TQFP 12x12x1mm TRAY
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F87K22-I/PTRSL

• A/d Inputs: 24-Channel, 12-Bit
• Comparators: 3
• Cpu Speed: 16 MIPS
• Eeprom Memory: 0 Bytes
• Input Output: 69
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 80-pin TQFP
• Programmable Memory: 128K Bytes
• Ram Size: 3.8K Bytes
• Speed: 64 MHz
• Temperature Range: –40 to 125 °C
• Timers: 6-8-bit, 5-16-bit
• Voltage, Range: 1.8-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC18F87K22 FAMILY
4.7
The Ultra Low-Power Wake-up (ULPWU) on pin, RA0,
allows a slow falling voltage to generate an interrupt
without excess current consumption.
To use this feature:
1.
2.
3.
4.
5.
When the voltage on RA0 drops below V
wakes up and executes the next instruction.
This feature provides a low-power technique for
periodically waking up the device from Sleep mode.
The time-out is dependent on the discharge time of the
RC circuit on RA0.
When the ULPWU module wakes the device from
Sleep mode, the ULPLVL bit (WDTCON<5>) is set.
Software can check this bit upon wake-up to determine
the wake-up source.
See
EXAMPLE 4-1:
DS39960C-page 70
TRISAbits.TRISA0 = 0;
PORTAbits.RA0 = 1;
for(i = 0; i < 10000; i++) Nop();
TRISAbits.TRISA0 = 1;
WDTCONbits.ULPEN = 1;
WDTCONbits.ULPSINK = 1;
OSCCONbits.IDLEN = 0;
Sleep();
Charge the capacitor on RA0 by configuring the
RA0 pin to an output and setting it to ‘1’.
Stop charging the capacitor by configuring RA0
as an input.
Discharge the capacitor by setting the ULPEN
and ULPSINK bits in the WDTCON register.
Configure Sleep mode.
Enter Sleep mode.
Example 4-1
Ultra Low-Power Wake-up
//***************************
//Charge the capacitor on RA0
//***************************
//*****************************
//Stop Charging the capacitor
//on RA0
//*****************************
//*****************************
//Enable the Ultra Low Power
//Wakeup module and allow
//capacitor discharge
//*****************************
//For Sleep
//Enter Sleep Mode
//
//for sleep, execution will
//resume here
for initializing the ULPWU module.
ULTRA LOW-POWER
WAKE-UP INITIALIZATION
IL
, the device
A series resistor, between RA0 and the external capac-
itor, provides overcurrent protection for the RA0/AN0/
ULPWU pin and enables software calibration of the
time-out (see
FIGURE 4-9:
A timer can be used to measure the charge time and
discharge time of the capacitor. The charge time can
then be adjusted to provide the desired delay in Sleep.
This technique compensates for the affects of temper-
ature, voltage and component accuracy. The peripheral
can also be configured as a simple Programmable
Low-Voltage Detect (LVD) or temperature sensor.
Note:
RA0/AN0/ULPWU
For more information, see AN879, “Using
the Microchip Ultra Low-Power Wake-up
Module” (DS00879).
Figure
4-9).
ULTRA LOW-POWER
WAKE-UP INITIALIZATION
 2011 Microchip Technology Inc.