PIC18F4550-IP Datasheet, PDF (140/438 Pages) Microchip Technology – 28/40/44-Pin, High-Performance, Enhanced Flash, USB Microcontrollers with nanoWatt Technology

PIC18F2455/2550/4455/4550
13.2 Timer2 Interrupt
Timer2 can also generate an optional device interrupt.
The Timer2 output signal (TMR2 to PR2 match) pro-
vides the input for the 4-bit output counter/postscaler.
This counter generates the TMR2 match interrupt flag
which is latched in TMR2IF (PIR1<1>). The interrupt is
enabled by setting the TMR2 Match Interrupt Enable
bit, TMR2IE (PIE1<1>).
A range of 16 postscale options (from 1:1 through 1:16
inclusive) can be selected with the postscaler control
bits, T2OUTPS3:T2OUTPS0 (T2CON<6:3>).
FIGURE 13-1:
TIMER2 BLOCK DIAGRAM
T2OUTPS3:T2OUTPS0
2
T2CKPS1:T2CKPS0
FOSC/4
1:1, 1:4, 1:16
Prescaler
Internal Data Bus
4
Reset
TMR2
8
13.3 TMR2 Output
The unscaled output of TMR2 is available primarily to
the CCP modules, where it is used as a time base for
operations in PWM mode.
Timer2 can be optionally used as the shift clock source
for the MSSP module operating in SPI mode.
Additional information is provided in Section 19.0
“Master Synchronous Serial Port (MSSP) Module”.
1:1 to 1:16
Postscaler
TMR2/PR2
Match
Comparator
8
Set TMR2IF
TMR2 Output
(to PWM or MSSP)
PR2
8
TABLE 13-1: REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER
Name Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE
RBIE TMR0IF INT0IF RBIF
53
PIR1
SPPIF⁽¹⁾
ADIF
RCIF
TXIF
SSPIF CCP1IF TMR2IF TMR1IF
56
PIE1
SPPIE⁽¹⁾
ADIE
RCIE
TXIE
SSPIE CCP1IE TMR2IE TMR1IE
56
IPR1
SPPIP⁽¹⁾
ADIP
RCIP
TXIP
SSPIP CCP1IP TMR2IP TMR1IP
56
TMR2 Timer2 Register
54
T2CON
— T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 54
PR2 Timer2 Period Register
54
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer2 module.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
DS39632E-page 138
© 2009 Microchip Technology Inc.