PIC18F2220/2320/4220/4320
14.0
TIMER3 MODULE
module.
register controls the operating mode of the Timer3
module and sets the CCP clock source.
register controls the operating mode of the Timer1
module, as well as contains the Timer1 Oscillator
Enable bit (T1OSCEN) which can be a clock source for
Timer3.
The Timer3 module timer/counter has the following
features:
• 16-bit timer/counter (two 8-bit registers: TMR3H
and TMR3L)
• Readable and writable (both registers)
• Internal or external clock select
• Interrupt-on-overflow from FFFFh to 0000h
• Reset from CCP module trigger
REGISTER 14-1:
T3CON: TIMER3 CONTROL REGISTER
R/W-0
RD16
bit 7
R/W-0
T3CCP2
R/W-0
T3CKPS1
R/W-0
T3CKPS0
R/W-0
T3CCP1
R/W-0
T3SYNC
R/W-0
TMR3CS
R/W-0
TMR3ON
bit 0
bit 7
RD16:
16-bit Read/Write Mode Enable bit
1
= Enables register read/write of Timer3 in one 16-bit operation
0
= Enables register read/write of Timer3 in two 8-bit operations
T3CCP2:T3CCP1:
Timer3 and Timer1 to CCPx Enable bits
1x
= Timer3 is the clock source for compare/capture CCP modules
01
= Timer3 is the clock source for compare/capture of CCP2,
Timer1 is the clock source for compare/capture of CCP1
00
= Timer1 is the clock source for compare/capture CCP modules
T3CKPS1:T3CKPS0:
Timer3 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
T3SYNC:
Timer3 External Clock Input Synchronization Control bit
(Not usable if the system clock comes from Timer1/Timer3.)
When TMR3CS =
1:
1
= Do not synchronize external clock input
0
= Synchronize external clock input
When TMR3CS =
0:
This bit is ignored. Timer3 uses the internal clock when TMR3CS =
0.
TMR3CS:
Timer3 Clock Source Select bit
1
= External clock input from Timer1 oscillator or T1CKI (on the rising edge after the first
falling edge)
0
= Internal clock (F
OSC
/4)
TMR3ON:
Timer3 On bit
1
= Enables Timer3
0
= Stops Timer3
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
bit 6, 3
bit 5-4
bit 2
bit 1
bit 0
2003 Microchip Technology Inc.
DS39599C-page 129
MICROCHIP [ MICROCHIP TECHNOLOGY ]
