
2004 Microchip Technology Inc.
DS30491C-page 155
PIC18F6585/8585/6680/8680
11.0
TIMER0 MODULE
The Timer0 module has the following features:
Software selectable as an 8-bit or 16-bit timer/
counter
Readable and writable
Dedicated 8-bit software programmable prescaler
Clock source selectable to be external or internal
Interrupt-on-overflow from 0FFh to 00h in 8-bit
mode and 0FFFFh to 0000h in 16-bit mode
Edge select for external clock
simplified block diagram of the Timer0 module in 16-bit
mode.
writable register that controls all the aspects of Timer0,
including the prescale selection.
REGISTER 11-1:
T0CON: TIMER0 CONTROL REGISTER
Note:
Timer0 is enabled on POR.
R/W-1
TMR0ON
T08BIT
T0CS
T0SE
PSA
T0PS2
T0PS1
T0PS0
bit 7
bit 0
bit 7
TMR0ON: Timer0 On/Off Control bit
1
= Enables Timer0
0
= Stops Timer0
bit 6
T08BIT: Timer0 8-bit/16-bit Control bit
1
= Timer0 is configured as an 8-bit timer/counter
0
= Timer0 is configured as a 16-bit timer/counter
bit 5
T0CS: Timer0 Clock Source Select bit
1
= Transition on T0CKI pin
0
= Internal instruction cycle clock (CLKO)
bit 4
T0SE: Timer0 Source Edge Select bit
1
= Increment on high-to-low transition on T0CKI pin
0
= Increment on low-to-high transition on T0CKI pin
bit 3
PSA: Timer0 Prescaler Assignment bit
1
= TImer0 prescaler is not assigned. Timer0 clock input bypasses prescaler.
0
= Timer0 prescaler is assigned. Timer0 clock input comes from prescaler output.
bit 2-0
T0PS2:T0PS0: Timer0 Prescaler Select bits
111
= 1:256 prescale value
110
= 1:128 prescale value
101
= 1:64 prescale value
100
= 1:32 prescale value
011
= 1:16 prescale value
010
= 1:8
prescale value
001
= 1:4
prescale value
000
= 1:2
prescale value
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
- n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown