PIC16F627A_05 Datasheet, PDF (50/180 Pages) Microchip Technology – Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology

PIC16F627A/628A/648A
7.0 TIMER1 MODULE
The Timer1 module is a 16-bit timer/counter consisting
of two 8-bit registers (TMR1H and TMR1L) which are
readable and writable. The TMR1 register pair
(TMR1H:TMR1L) increments from 0000h to FFFFh
and rolls over to 0000h. The Timer1 Interrupt, if
enabled, is generated on overflow of the TMR1 register
pair which latches the interrupt flag bit TMR1IF
(PIR1<0>). This interrupt can be enabled/disabled by
setting/clearing the Timer1 interrupt enable bit TMR1IE
(PIE1<0>).
Timer1 can operate in one of two modes:
• As a timer
• As a counter
The Operating mode is determined by the clock select
bit, TMR1CS (T1CON<1>).
In Timer mode, the TMR1 register pair value
increments every instruction cycle. In Counter mode, it
increments on every rising edge of the external clock
input.
Timer1 can be enabled/disabled by setting/clearing
control bit TMR1ON (T1CON<0>).
Timer1 also has an internal “Reset input”. This Reset
can be generated by the CCP module (Section 9.0
“Capture/Compare/PWM (CCP) Module”).
Register 7-1 shows the Timer1 control register.
For the PIC16F627A/628A/648A, when the Timer1
oscillator is enabled (T1OSCEN is set), the RB7/
T1OSI/PGD and RB6/T1OSO/T1CKI/PGC pins
become inputs. That is, the TRISB<7:6> value is
ignored.
REGISTER 7-1:
T1CON – TIMER1 CONTROL REGISTER (ADDRESS: 10h)
U-0
U-0
R/W-0 R/W-0
R/W-0
R/W-0 R/W-0 R/W-0
—
— T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON
bit 7
bit 0
bit 7-6
bit 5-4
bit 3
bit 2
bit 1
bit 0
Unimplemented: Read as ‘0’
T1CKPS<1:0>: Timer1 Input Clock Prescale Select bits
11 = 1:8 Prescale value
10 = 1:4 Prescale value
01 = 1:2 Prescale value
00 = 1:1 Prescale value
T1OSCEN: Timer1 Oscillator Enable Control bit
1 = Oscillator is enabled
0 = Oscillator is shut off⁽¹⁾
T1SYNC: Timer1 External Clock Input Synchronization Control bit
TMR1CS = 1
1 = Do not synchronize external clock input
0 = Synchronize external clock input
TMR1CS = 0
This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0.
TMR1CS: Timer1 Clock Source Select bit
1 = External clock from pin RB6/T1OSO/T1CKI/PGC (on the rising edge)
0 = Internal clock (FOSC/4)
TMR1ON: Timer1 On bit
1 = Enables Timer1
0 = Stops Timer1
Note 1: The oscillator inverter and feedback resistor are turned off to eliminate power drain.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS40044D-page 48
© 2005 Microchip Technology Inc.