PIC18F45K20-E/P Microchip Technology, PIC18F45K20-E/P Datasheet - Page 55

• Manufacturer Part Number: PIC18F45K20-E/P
• Description: 32KB, Flash, 1536bytes-RAM, 36I/O, 8-bit Family,nanowatt XLP 40 PDIP .600in TUBE
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 18Fr

Specifications of PIC18F45K20-E/P

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 1.5K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: DM240313 - BOARD DEMO 8BIT XLPAC164112 - VOLTAGE LIMITER MPLAB ICD2 VPPDM164124 - KIT STARTER FOR PIC18F4XK20
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

FIGURE 3-41:
© 2009 Microchip Technology Inc.
/**
//----------------------------------------------------------------------------
//
#pragma code InterruptVectorHigh = 0x08
void InterruptVectorHigh (void)
{
}
//----------------------------------------------------------------------------
//
#pragma code InterruptVectorLow =
0x18 void InterruptVectorLow (void)
{
}
_asm
_endasm
_asm
High
goto InterruptServiceHigh //jump to interrupt routine
Low
goto InterruptServiceLow //jump to interrupt routine _endasm
I
N
priority
priority
T
E
R
DEFINE INTERRUPT VECTORS
interrupt
The Interrupt Service Routine functions themselves are then declared with the
#pragma interrupt directive for the high priority vector, and #pragma
interruptlow for the low priority. Note the names must match between the vector
GOTO argument, the #pragma attribute, and the function declaration name. The
interrupt functions may call other functions defined elsewhere in the source, though the
lesson source code does not do this.
FIGURE 3-42:
As all interrupts of the same priority vector to the same function, it is necessary in the
function to examine which of the enabled interrupt flags caused the interrupt. Once the
flag is found so that peripheral or event may be serviced, the software must clear the
interrupt flag bit to reset the interrupt. In the lesson source code, the high priority
interrupt routine looks for the INT0 pin interrupt INT0IF flag bit. Examples are shown in
the source code of how it might check for other enabled interrupts, such as Timer1
TMR1IF and the ADC ADIF although neither of these interrupts are enabled in the
lesson code. Similarly, the low priority vector checks for the Timer0 flag TMR0IF.
Setting Up Interrupts
Now that the source code has defined the interrupt vectors, and has functions to deal
with the interrupts, it must properly setup and configure the interrupting logic and
enable the individual interrupts it wants to use.
Timer0 and external pin interrupts are set up using the INTCONx Special Function
Registers. Other interrupts are setup through a number set of peripheral interrupt
SFRs: PIRx, PIEx and IPRx. The PIRx registers contain the interrupt flags. The
R
interrupt
//
#pragma
void
{
}
#pragma interruptlow InterruptServiceLow // "interruptlow" pragma for low priority
void InterruptServiceLow(void)
{
}
U
P
//function
//
//function
//
InterruptServiceHigh(void)
T
vector
interrupt
return
return
vector
S
***********************************************/
statements
from
statements
from
PICkit™ 3 Debug Express Lessons
INTERRUPT SERVICE FUNCTIONS
Iterrupt
InterruptServiceHigh//
high-priority
low-priority
Service
interrupt
interrupt
Routines
"interrupt"
pragma
for
high
DS41370C-page 51
priority